From a1d040dc1949a84f839321510d73aeb385a348fb Mon Sep 17 00:00:00 2001
From: chardon55 <charlesdong_2000@outlook.com>
Date: Wed, 26 Oct 2022 16:11:55 +0800
Subject: [PATCH 01/22] Update const return types

---
 include/abstract_encoder.hpp      |  2 +-
 include/abstract_hash_encoder.hpp | 11 +++++++++
 include/hash_encoder.hpp          | 14 +++---------
 include/hmac_encoder.hpp          | 12 +---------
 include/sequential_data.hpp       | 23 ++++++++++---------
 src/hash_encoder.cpp              | 25 ++++++++++++---------
 src/hmac_encoder.cpp              | 10 ++++-----
 src/sequential_data.cpp           | 37 ++++++++++++++++++++++---------
 test/hash_encoder_test.hpp        |  1 -
 test/hmactest.hpp                 |  6 ++---
 10 files changed, 77 insertions(+), 64 deletions(-)

diff --git a/include/abstract_encoder.hpp b/include/abstract_encoder.hpp
index 2084fa2..3ed552c 100644
--- a/include/abstract_encoder.hpp
+++ b/include/abstract_encoder.hpp
@@ -39,7 +39,7 @@ class AbstractEncoder
         update(sd.to_pgfe_seq(sz), sz);
     }
 
-    virtual SequentialData *get_digest() {
+    virtual const SequentialData *get_digest() {
         return nullptr;
     }
 }; // namespace AbstractEncoder
diff --git a/include/abstract_hash_encoder.hpp b/include/abstract_hash_encoder.hpp
index 6728a0b..4d9f29b 100644
--- a/include/abstract_hash_encoder.hpp
+++ b/include/abstract_hash_encoder.hpp
@@ -24,6 +24,17 @@ namespace PGFE {
 
 class AbstractHashEncoder : public AbstractEncoder, public AlgorithmSelectable
 {
+protected:
+    size_t digsz, blocksz;
+
+public:
+    size_t digest_size() const {
+        return digsz;
+    }
+
+    size_t block_size() const {
+        return blocksz;
+    }
 };
 
 } // namespace PGFE
diff --git a/include/hash_encoder.hpp b/include/hash_encoder.hpp
index 7029fee..3dd5f42 100644
--- a/include/hash_encoder.hpp
+++ b/include/hash_encoder.hpp
@@ -25,12 +25,12 @@ class HashEncoder : public AbstractHashEncoder
 private:
     void *ctx = nullptr;
 
-    size_t digsz, blocksz;
-    pgfe_encode_t *seq = nullptr;
+    SequentialData *out = nullptr;
 
     void load_algorithm();
 
     void destroy_context();
+    void destroy_output();
 
     void init();
 
@@ -49,15 +49,7 @@ class HashEncoder : public AbstractHashEncoder
     void update(std::string &cpp_s);
     void update(SequentialData &sd);
 
-    SequentialData *get_digest(uint64_t bitlength = 0);
-
-    size_t digest_size() {
-        return digsz;
-    }
-
-    size_t block_size() {
-        return blocksz;
-    }
+    const SequentialData *get_digest(uint64_t bitlength = 0);
 };
 
 } // namespace PGFE
diff --git a/include/hmac_encoder.hpp b/include/hmac_encoder.hpp
index c8d4c44..521ad71 100644
--- a/include/hmac_encoder.hpp
+++ b/include/hmac_encoder.hpp
@@ -40,8 +40,6 @@ class HMACEncoder : public AbstractHashEncoder
         pgfe_hmac_sha3_512_ctx sha3_512;
     } ctx;
 
-    size_t digsz, blocksz;
-
     SequentialData *output;
 
     void destroy_output();
@@ -66,15 +64,7 @@ class HMACEncoder : public AbstractHashEncoder
     void update(std::string &cpp_s);
     void update(SequentialData &sd);
 
-    SequentialData *get_digest();
-
-    size_t block_size() {
-        return blocksz;
-    }
-
-    size_t digest_size() {
-        return digsz;
-    }
+    const SequentialData *get_digest();
 };
 
 } // namespace PGFE
diff --git a/include/sequential_data.hpp b/include/sequential_data.hpp
index a81484d..90829f5 100644
--- a/include/sequential_data.hpp
+++ b/include/sequential_data.hpp
@@ -40,27 +40,30 @@ class SequentialData
     SequentialData(const pgfe_encode_t *, size_t);
     SequentialData(const char *);
     SequentialData(std::string &);
+    SequentialData(const SequentialData *);
+    SequentialData(SequentialData *, bool delete_current);
     ~SequentialData();
 
-    const char *to_cs();
-    std::string to_str();
+    const char *to_cs() const;
+    std::string to_str() const;
 
     const char *to_hex_cs();
-    std::string to_hex_str();
+    std::string to_hex_str() const;
 
-    const pgfe_encode_t *to_pgfe_seq();
-    const pgfe_encode_t *to_pgfe_seq(size_t &);
+    const pgfe_encode_t *to_pgfe_seq() const;
+    const pgfe_encode_t *to_pgfe_seq(size_t &) const;
 
-    size_t length();
+    size_t length() const;
 
-    bool is_str();
+    bool is_str() const;
     void set_is_str(bool);
 
-    bool is_apparent_str();
+    bool is_apparent_str() const;
 
-    SequentialData *truncate(size_t start, size_t length, bool inplace = false);
+    SequentialData *truncate(size_t start, size_t length, bool inplace);
+    SequentialData *truncate(size_t start, size_t length) const;
 
-    SequentialData *copy();
+    SequentialData *copy() const;
 
     friend std::ostream &operator<<(std::ostream &os, const SequentialData &sd) {
         if (sd._is_str) {
diff --git a/src/hash_encoder.cpp b/src/hash_encoder.cpp
index ad20f06..8271a33 100644
--- a/src/hash_encoder.cpp
+++ b/src/hash_encoder.cpp
@@ -55,6 +55,13 @@ void HashEncoder::destroy_context() {
     __PGFE_BATCH_CASES(CTX_DELETE)
 }
 
+void HashEncoder::destroy_output() {
+    if (!out) return;
+
+    delete out;
+    out = nullptr;
+}
+
 void HashEncoder::before_change_alg() {
     destroy_context();
 }
@@ -67,11 +74,6 @@ void HashEncoder::load_algorithm() {
     __PGFE_BATCH_CASES(CTX_CREATE)
     __PGFE_BATCH_CASES(INIT_FUNC_CALL)
     __PGFE_BATCH_CASES(INIT_SIZE)
-
-    if (seq) {
-        delete[] seq;
-    }
-    seq = new pgfe_encode_t[digsz + 1];
 }
 
 void HashEncoder::reset() {
@@ -90,9 +92,7 @@ HashEncoder::HashEncoder(pgfe_algorithm_choice choice) {
 
 HashEncoder::~HashEncoder() {
     destroy_context();
-    if (seq) {
-        delete[] seq;
-    }
+    destroy_output();
 }
 
 void HashEncoder::update(const pgfe_encode_t sequence[], size_t length) {
@@ -111,7 +111,7 @@ inline void HashEncoder::update(SequentialData &sd) {
     return this->AbstractHashEncoder::update(sd);
 }
 
-SequentialData *HashEncoder::get_digest(uint64_t bitlength) {
+const SequentialData *HashEncoder::get_digest(uint64_t bitlength) {
     bool shake_flag = this->cur_alg == SHAKE128 || this->cur_alg == RawSHAKE128 || this->cur_alg == SHAKE256 ||
                       this->cur_alg == RawSHAKE256;
     uint64_t in_len = to_byte(bitlength) + bit_rem(bitlength);
@@ -125,6 +125,9 @@ SequentialData *HashEncoder::get_digest(uint64_t bitlength) {
         }
     }
 
+    size_t length = shake_flag ? in_len : in_len < digsz && bitlength ? in_len : digsz;
+    pgfe_encode_t seq[length];
+
     if (shake_flag) {
         __PGFE_BATCH_SHAKE_CASES(DIGEST_FUNC_CALL_LIMIT)
     }
@@ -132,5 +135,7 @@ SequentialData *HashEncoder::get_digest(uint64_t bitlength) {
         __PGFE_BATCH_CASES_SP(DIGEST_FUNC_CALL)
     }
 
-    return new SequentialData(seq, shake_flag ? in_len : in_len < digsz && bitlength ? in_len : digsz);
+    destroy_output();
+    out = new SequentialData(seq, length);
+    return out;
 }
\ No newline at end of file
diff --git a/src/hmac_encoder.cpp b/src/hmac_encoder.cpp
index 5e69d9e..6fec1c8 100644
--- a/src/hmac_encoder.cpp
+++ b/src/hmac_encoder.cpp
@@ -101,10 +101,8 @@ inline void HMACEncoder::update(SequentialData &sd) {
     this->AbstractHashEncoder::update(sd);
 }
 
-SequentialData *HMACEncoder::get_digest() {
-    if (!output) {
-        __PGFE_BATCH_CASES_SP(HMAC_DIGEST)
-    }
-
-    return output->copy();
+const SequentialData *HMACEncoder::get_digest() {
+    destroy_output();
+    __PGFE_BATCH_CASES_SP(HMAC_DIGEST)
+    return output;
 }
\ No newline at end of file
diff --git a/src/sequential_data.cpp b/src/sequential_data.cpp
index a1b95fc..b500a52 100644
--- a/src/sequential_data.cpp
+++ b/src/sequential_data.cpp
@@ -34,15 +34,24 @@ SequentialData::SequentialData(const char *cs) : SequentialData((const pgfe_enco
 SequentialData::SequentialData(std::string &cpp_s)
     : SequentialData((const pgfe_encode_t *)cpp_s.c_str(), cpp_s.length()) {}
 
-size_t SequentialData::length() {
+SequentialData::SequentialData(const SequentialData *sd) : SequentialData((const pgfe_encode_t *)sd->seq, sd->sz) {}
+
+SequentialData::SequentialData(SequentialData *sd, bool delete_current)
+    : SequentialData((const pgfe_encode_t *)sd->seq, sd->sz) {
+    if (delete_current) {
+        delete sd;
+    }
+}
+
+size_t SequentialData::length() const {
     return sz;
 }
 
-const char *SequentialData::to_cs() {
+const char *SequentialData::to_cs() const {
     return (const char *)seq;
 }
 
-std::string SequentialData::to_str() {
+std::string SequentialData::to_str() const {
     std::string s((char *)seq);
     return s;
 }
@@ -57,21 +66,23 @@ const char *SequentialData::to_hex_cs() {
     return hex_str;
 }
 
-std::string SequentialData::to_hex_str() {
-    std::string s(to_hex_cs());
+std::string SequentialData::to_hex_str() const {
+    char hex_str[sz * 2 + 1];
+    pgfe_hash_to_hex_string(seq, sz, hex_str);
+    std::string s(hex_str);
     return s;
 }
 
-const pgfe_encode_t *SequentialData::to_pgfe_seq() {
+const pgfe_encode_t *SequentialData::to_pgfe_seq() const {
     return seq;
 }
 
-const pgfe_encode_t *SequentialData::to_pgfe_seq(size_t &length_out) {
+const pgfe_encode_t *SequentialData::to_pgfe_seq(size_t &length_out) const {
     length_out = sz;
     return to_pgfe_seq();
 }
 
-bool SequentialData::is_str() {
+bool SequentialData::is_str() const {
     return _is_str;
 }
 
@@ -79,7 +90,7 @@ void SequentialData::set_is_str(bool str) {
     _is_str = str;
 }
 
-bool SequentialData::is_apparent_str() {
+bool SequentialData::is_apparent_str() const {
     return _apstr;
 }
 
@@ -93,6 +104,10 @@ bool SequentialData::determine_ascii_str() {
     return true;
 }
 
+SequentialData *SequentialData::truncate(size_t start, size_t length) const {
+    return new SequentialData(&seq[start], length);
+}
+
 SequentialData *SequentialData::truncate(size_t start, size_t length, bool inplace) {
     if (inplace) {
         if (start) {
@@ -104,9 +119,9 @@ SequentialData *SequentialData::truncate(size_t start, size_t length, bool inpla
         return nullptr;
     }
 
-    return new SequentialData(&seq[start], length);
+    return truncate(start, length);
 }
 
-SequentialData *SequentialData::copy() {
+SequentialData *SequentialData::copy() const {
     return new SequentialData((const pgfe_encode_t *)seq, sz);
 }
\ No newline at end of file
diff --git a/test/hash_encoder_test.hpp b/test/hash_encoder_test.hpp
index 48c9aad..fdf6b1f 100644
--- a/test/hash_encoder_test.hpp
+++ b/test/hash_encoder_test.hpp
@@ -32,5 +32,4 @@ void hash_encoder_test(ARGS) {
 
     // puts(sd.to_hex_cs());
     cout << *sd << endl;
-    delete sd;
 }
\ No newline at end of file
diff --git a/test/hmactest.hpp b/test/hmactest.hpp
index e7ca2c3..418f276 100644
--- a/test/hmactest.hpp
+++ b/test/hmactest.hpp
@@ -28,8 +28,8 @@ void hmac_encoder_test(ARGS) {
 
     encoder->update(argv[4]);
 
-    auto sd = encoder->get_digest();
-    puts(sd->to_hex_cs());
-    delete sd;
+    SequentialData sd{encoder->get_digest()};
+    puts(sd.to_hex_cs());
+
     delete encoder;
 }

From 9b18c2a739ce3e673c3815d25eaf15e89aab6fa9 Mon Sep 17 00:00:00 2001
From: chardon55 <charlesdong_2000@outlook.com>
Date: Wed, 26 Oct 2022 16:12:42 +0800
Subject: [PATCH 02/22] Update version number

---
 CMakeLists.txt | 2 +-
 include/meta.h | 4 ++--
 meta.mak       | 2 +-
 3 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 656c329..23f6d91 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -3,7 +3,7 @@ cmake_minimum_required(VERSION 3.16.0)
 set(CMAKE_C_COMPILER clang)
 set(CMAKE_CXX_COMPILER clang++)
 
-project(libpgfe VERSION 0.4.0 LANGUAGES C CXX)
+project(libpgfe VERSION 0.5.0 LANGUAGES C CXX)
 
 set(CMAKE_C_STANDARD 11)
 set(CMAKE_CXX_STANDARD 14)
diff --git a/include/meta.h b/include/meta.h
index 9304ec4..e5aa612 100644
--- a/include/meta.h
+++ b/include/meta.h
@@ -11,8 +11,8 @@
 #define LIBPGFE_NAME "libpgfe"
 
 #define LIBPGFE_MAJOR_VERSION 0
-#define LIBPGFE_MINOR_VERSION 4
+#define LIBPGFE_MINOR_VERSION 5
 #define LIBPGFE_REVISION 0
 
-#define LIBPGFE_VERSION "0.4.0"
+#define LIBPGFE_VERSION "0.5.0"
 #endif
diff --git a/meta.mak b/meta.mak
index 802b863..0aa05e0 100644
--- a/meta.mak
+++ b/meta.mak
@@ -1,5 +1,5 @@
 PROJECT := libpgfe
-VERSION := 0.4.0
+VERSION := 0.5.0
 
 BUILD_DIR := build
 

From 8bd1d399da293541ecc997122887c5db8e81b42a Mon Sep 17 00:00:00 2001
From: chardon55 <charlesdong_2000@outlook.com>
Date: Wed, 26 Oct 2022 16:31:09 +0800
Subject: [PATCH 03/22] Update const methods

---
 include/abstract_base_encoding.hpp | 8 ++++----
 include/abstract_otp.hpp           | 4 ++--
 include/algorithm_selectable.hpp   | 2 +-
 include/base32.hpp                 | 2 +-
 include/base64.hpp                 | 2 +-
 include/generic.hpp                | 6 +++---
 include/hotp.hpp                   | 4 ++--
 include/totp.hpp                   | 8 ++++----
 src/abstract_base_encoding.cpp     | 8 ++++----
 src/abstract_otp.cpp               | 2 +-
 src/algorithm_selectable.cpp       | 2 +-
 src/hotp.cpp                       | 4 ++--
 src/totp.cpp                       | 8 ++++----
 src/utils.cpp                      | 2 +-
 14 files changed, 31 insertions(+), 31 deletions(-)

diff --git a/include/abstract_base_encoding.hpp b/include/abstract_base_encoding.hpp
index 42e705b..4a9790e 100644
--- a/include/abstract_base_encoding.hpp
+++ b/include/abstract_base_encoding.hpp
@@ -63,10 +63,10 @@ class AbstractBaseEncoding
     SequentialData decode(const char *);
     SequentialData decode(std::string &);
 
-    base_short_size_t unit_size();
-    base_short_size_t chunk_size();
-    base_short_size_t bit_size();
-    base_short_size_t alphabet_size();
+    base_short_size_t unit_size() const;
+    base_short_size_t chunk_size() const;
+    base_short_size_t bit_size() const;
+    base_short_size_t alphabet_size() const;
 };
 
 } // namespace PGFE
diff --git a/include/abstract_otp.hpp b/include/abstract_otp.hpp
index 05b6152..79c51ac 100644
--- a/include/abstract_otp.hpp
+++ b/include/abstract_otp.hpp
@@ -31,11 +31,11 @@ class AbstractOTP : public AlgorithmSelectable
 
     virtual void set_counter(pgfe_otp_counter_t){};
 
-    virtual pgfe_otp_t generate(uint8_t digit_count = 6) {
+    virtual pgfe_otp_t generate(uint8_t digit_count = 6) const {
         return 0;
     }
 
-    virtual std::string generate_str(uint8_t digit_count = 6);
+    virtual std::string generate_str(uint8_t digit_count = 6) const;
 };
 
 } // namespace PGFE
diff --git a/include/algorithm_selectable.hpp b/include/algorithm_selectable.hpp
index 98f1396..a7240e0 100644
--- a/include/algorithm_selectable.hpp
+++ b/include/algorithm_selectable.hpp
@@ -28,7 +28,7 @@ class AlgorithmSelectable
     void select_algorithm(pgfe_algorithm_choice choice);
 
 public:
-    pgfe_algorithm_choice algorithm();
+    pgfe_algorithm_choice algorithm() const;
 };
 } // namespace PGFE
 } // namespace chardon55
diff --git a/include/base32.hpp b/include/base32.hpp
index f8e06d8..01a7eeb 100644
--- a/include/base32.hpp
+++ b/include/base32.hpp
@@ -28,7 +28,7 @@ class Base32 : public AbstractBaseEncoding
 public:
     Base32(bool hex_mode = false);
 
-    bool is_hex_mode() {
+    bool is_hex_mode() const {
         return hexm;
     }
 };
diff --git a/include/base64.hpp b/include/base64.hpp
index dbf7ae6..dc01fb6 100644
--- a/include/base64.hpp
+++ b/include/base64.hpp
@@ -28,7 +28,7 @@ class Base64 : public AbstractBaseEncoding
 public:
     Base64(bool url_safe_mode = false);
 
-    bool is_url_safe_mode() {
+    bool is_url_safe_mode() const {
         return _url_safe_mode;
     }
 };
diff --git a/include/generic.hpp b/include/generic.hpp
index 09fbaa4..ff0d83a 100644
--- a/include/generic.hpp
+++ b/include/generic.hpp
@@ -102,7 +102,7 @@
 namespace chardon55 {
 namespace PGFE {
 
-static std::unordered_map<std::string, pgfe_algorithm_choice> pgfe_option_map = {
+static const std::unordered_map<std::string, pgfe_algorithm_choice> pgfe_option_map = {
     {"sha1",        SHA1       },
     {"SHA1",        SHA1       },
     {"sha224",      SHA224     },
@@ -137,7 +137,7 @@ static std::unordered_map<std::string, pgfe_algorithm_choice> pgfe_option_map =
     {"MD5",         MD5        },
 };
 
-static std::unordered_map<pgfe_algorithm_choice, size_t> pgfe_digest_length = {
+static const std::unordered_map<pgfe_algorithm_choice, size_t> pgfe_digest_length = {
     {SHA1,        PGFE_SHA1_DIGEST_SIZE       },
     {SHA224,      PGFE_SHA224_DIGEST_SIZE     },
     {SHA256,      PGFE_SHA256_DIGEST_SIZE     },
@@ -156,7 +156,7 @@ static std::unordered_map<pgfe_algorithm_choice, size_t> pgfe_digest_length = {
     {RawSHAKE256, PGFE_RawSHAKE256_DIGEST_SIZE},
 };
 
-static std::unordered_map<pgfe_algorithm_choice, size_t> pgfe_block_length = {
+static const std::unordered_map<pgfe_algorithm_choice, size_t> pgfe_block_length = {
     {SHA1,        PGFE_SHA1_BLOCK_SIZE       },
     {SHA224,      PGFE_SHA224_BLOCK_SIZE     },
     {SHA256,      PGFE_SHA256_BLOCK_SIZE     },
diff --git a/include/hotp.hpp b/include/hotp.hpp
index 37ee89b..fb594ff 100644
--- a/include/hotp.hpp
+++ b/include/hotp.hpp
@@ -50,8 +50,8 @@ class HOTP : public AbstractOTP
 
     void set_counter(pgfe_otp_counter_t);
 
-    pgfe_otp_t generate(uint8_t digit_count = 6);
-    std::string generate_str(uint8_t digit_count = 6);
+    pgfe_otp_t generate(uint8_t digit_count = 6) const;
+    std::string generate_str(uint8_t digit_count = 6) const;
 };
 
 } // namespace PGFE
diff --git a/include/totp.hpp b/include/totp.hpp
index f958dc5..949d7a4 100644
--- a/include/totp.hpp
+++ b/include/totp.hpp
@@ -35,15 +35,15 @@ class TOTP : public HOTP
 
     void update_counter();
 
-    pgfe_totp_interval_t get_interval();
+    pgfe_totp_interval_t get_interval() const;
     void set_interval(pgfe_totp_interval_t);
 
-    pgfe_time_t get_initial_time();
+    pgfe_time_t get_initial_time() const;
     void set_initial_time(pgfe_time_t);
 
-    pgfe_time_t get_update_time();
+    pgfe_time_t get_update_time() const;
 
-    pgfe_time_t get_remain_time();
+    pgfe_time_t get_remain_time() const;
 };
 
 } // namespace PGFE
diff --git a/src/abstract_base_encoding.cpp b/src/abstract_base_encoding.cpp
index 0d6f007..c2f13b9 100644
--- a/src/abstract_base_encoding.cpp
+++ b/src/abstract_base_encoding.cpp
@@ -94,18 +94,18 @@ SequentialData AbstractBaseEncoding::decode(std::string &cpp_s) {
     return decode(cpp_s.c_str());
 }
 
-base_short_size_t AbstractBaseEncoding::unit_size() {
+base_short_size_t AbstractBaseEncoding::unit_size() const {
     return unitsz;
 }
 
-base_short_size_t AbstractBaseEncoding::chunk_size() {
+base_short_size_t AbstractBaseEncoding::chunk_size() const {
     return chunksz;
 }
 
-base_short_size_t AbstractBaseEncoding::bit_size() {
+base_short_size_t AbstractBaseEncoding::bit_size() const {
     return bitsz;
 }
 
-base_short_size_t AbstractBaseEncoding::alphabet_size() {
+base_short_size_t AbstractBaseEncoding::alphabet_size() const {
     return alphabetsz;
 }
\ No newline at end of file
diff --git a/src/abstract_otp.cpp b/src/abstract_otp.cpp
index ec7e832..c088524 100644
--- a/src/abstract_otp.cpp
+++ b/src/abstract_otp.cpp
@@ -26,7 +26,7 @@ void AbstractOTP::set_secret(SequentialData &sd) {
     set_secret(sd.to_pgfe_seq(sz), sz);
 }
 
-std::string AbstractOTP::generate_str(uint8_t digit_count) {
+std::string AbstractOTP::generate_str(uint8_t digit_count) const {
     std::string str = std::to_string(generate(digit_count));
     while (str.length() < digit_count) {
         str.insert(0, "0");
diff --git a/src/algorithm_selectable.cpp b/src/algorithm_selectable.cpp
index c2ca56a..7f6e1b9 100644
--- a/src/algorithm_selectable.cpp
+++ b/src/algorithm_selectable.cpp
@@ -10,6 +10,6 @@ void AlgorithmSelectable::select_algorithm(pgfe_algorithm_choice choice) {
     after_change_alg();
 }
 
-pgfe_algorithm_choice AlgorithmSelectable::algorithm() {
+pgfe_algorithm_choice AlgorithmSelectable::algorithm() const {
     return cur_alg;
 }
\ No newline at end of file
diff --git a/src/hotp.cpp b/src/hotp.cpp
index ea844d7..222237a 100644
--- a/src/hotp.cpp
+++ b/src/hotp.cpp
@@ -81,7 +81,7 @@ void HOTP::set_counter(pgfe_otp_counter_t c) {
     this->co = c;
 }
 
-pgfe_otp_t HOTP::generate(uint8_t digit_count) {
+pgfe_otp_t HOTP::generate(uint8_t digit_count) const {
     if (!secret) {
         throw NotInitializedException();
     }
@@ -89,7 +89,7 @@ pgfe_otp_t HOTP::generate(uint8_t digit_count) {
     return pgfe_hotp_generic(cur_alg, secret->to_pgfe_seq(), secret->length(), co, digit_count);
 }
 
-std::string HOTP::generate_str(uint8_t digit_count) {
+std::string HOTP::generate_str(uint8_t digit_count) const {
     return this->AbstractOTP::generate_str(digit_count);
 }
 
diff --git a/src/totp.cpp b/src/totp.cpp
index 05fa8bf..f791cc5 100644
--- a/src/totp.cpp
+++ b/src/totp.cpp
@@ -15,11 +15,11 @@ void TOTP::set_interval(pgfe_totp_interval_t interval) {
     this->interval = interval;
 }
 
-pgfe_totp_interval_t TOTP::get_interval() {
+pgfe_totp_interval_t TOTP::get_interval() const {
     return interval;
 }
 
-pgfe_time_t TOTP::get_initial_time() {
+pgfe_time_t TOTP::get_initial_time() const {
     return initial_time;
 }
 
@@ -27,7 +27,7 @@ void TOTP::set_initial_time(pgfe_time_t initial_time) {
     this->initial_time = initial_time;
 }
 
-pgfe_time_t TOTP::get_update_time() {
+pgfe_time_t TOTP::get_update_time() const {
     return update_time;
 }
 
@@ -36,7 +36,7 @@ void TOTP::update_counter() {
     set_counter(__pgfe_calc_periodic_counter(update_time, interval, initial_time, &delta));
 }
 
-pgfe_time_t TOTP::get_remain_time() {
+pgfe_time_t TOTP::get_remain_time() const {
     return delta - (pgfe_curtime() - update_time);
 }
 
diff --git a/src/utils.cpp b/src/utils.cpp
index 667fb66..10ab468 100644
--- a/src/utils.cpp
+++ b/src/utils.cpp
@@ -47,7 +47,7 @@ pgfe_algorithm_choice string_to_algorithm_choice(const char *cs) {
 }
 
 pgfe_algorithm_choice string_to_algorithm_choice(std::string cpp_s) {
-    return pgfe_option_map[cpp_s];
+    return pgfe_option_map.at(cpp_s);
 }
 
 } // namespace utils

From e789dc9f1793d5364306bd2b1e2742d44d392005 Mon Sep 17 00:00:00 2001
From: chardon55 <charlesdong_2000@outlook.com>
Date: Wed, 26 Oct 2022 16:33:10 +0800
Subject: [PATCH 04/22] Update dispose function

---
 src/hmac_encoder.cpp | 1 +
 1 file changed, 1 insertion(+)

diff --git a/src/hmac_encoder.cpp b/src/hmac_encoder.cpp
index 6fec1c8..31467d9 100644
--- a/src/hmac_encoder.cpp
+++ b/src/hmac_encoder.cpp
@@ -36,6 +36,7 @@ using namespace chardon55::PGFE;
 void HMACEncoder::destroy_output() {
     if (output) {
         delete output;
+        output = nullptr;
     }
 }
 

From df4b252966e388c1370b679f326ec3a5d3542f7c Mon Sep 17 00:00:00 2001
From: chardon55 <charlesdong_2000@outlook.com>
Date: Wed, 26 Oct 2022 16:47:14 +0800
Subject: [PATCH 05/22] Update Q&A

---
 .github/qna.md | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/.github/qna.md b/.github/qna.md
index c32e861..dab3a96 100644
--- a/.github/qna.md
+++ b/.github/qna.md
@@ -17,7 +17,7 @@ and I currently don't have enough time or effort to tackle it. Also, I do not ha
 
 Firstly, this library prioritizes POSIX compatibility, instead of Windows compatibility.
 
-Secondly, *libpgfe* need some necessary features that are not included in *MSVC*. For instance, like the C code below:
+Secondly, *libpgfe* needs some necessary features that are not included in *MSVC*. For instance, like the C code below:
 
 ```c
 int main() {
@@ -28,4 +28,4 @@ int main() {
 }
 ```
 
-*MSVC* will refuse to compile that code, because of a variable is used as the array's size, while *Clang* and *GCC* are OK with it.
+*MSVC* will refuse to compile that code, because a variable is used as the array's size, while *Clang* and *GCC* are OK with it.

From 8ec382718067de602078cc2cdef342caeb11b99e Mon Sep 17 00:00:00 2001
From: chardon55 <charlesdong_2000@outlook.com>
Date: Sun, 30 Oct 2022 10:51:34 +0800
Subject: [PATCH 06/22] Refactoring

---
 src/sequential_data.cpp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/sequential_data.cpp b/src/sequential_data.cpp
index b500a52..4dd426b 100644
--- a/src/sequential_data.cpp
+++ b/src/sequential_data.cpp
@@ -52,7 +52,7 @@ const char *SequentialData::to_cs() const {
 }
 
 std::string SequentialData::to_str() const {
-    std::string s((char *)seq);
+    std::string s{(char *)seq};
     return s;
 }
 

From 821a565c5c547c80ce61d86873238b3ba97942d6 Mon Sep 17 00:00:00 2001
From: chardon55 <charlesdong_2000@outlook.com>
Date: Sun, 30 Oct 2022 11:21:13 +0800
Subject: [PATCH 07/22] Add source entry

---
 CMakeLists.txt | 1 +
 1 file changed, 1 insertion(+)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 23f6d91..0fb32bf 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -33,6 +33,7 @@ add_library(pgfe SHARED
     ${src_dir}/hotp.c ${src_dir}/totp.c
     ${src_dir}/base-encoding-internal.c
     ${src_dir}/base64.c ${src_dir}/base32.c ${src_dir}/base16.c
+    ${src_dir}/generic.cpp
     ${src_dir}/sequential_data.cpp
     ${src_dir}/utils.cpp
     ${src_dir}/algorithm_selectable.cpp

From 0c9ab0d52b345792d3c416f970d0f2db6aa9bc4c Mon Sep 17 00:00:00 2001
From: chardon55 <charlesdong_2000@outlook.com>
Date: Sun, 30 Oct 2022 11:21:53 +0800
Subject: [PATCH 08/22] Move string2ac to generic

---
 include/generic.hpp     |  5 +++++
 include/utils.hpp       |  3 ---
 src/generic.cpp         | 23 +++++++++++++++++++++++
 src/sequential_data.cpp |  4 +---
 src/utils.cpp           |  9 ---------
 test/hmactest.hpp       |  1 -
 6 files changed, 29 insertions(+), 16 deletions(-)
 create mode 100644 src/generic.cpp

diff --git a/include/generic.hpp b/include/generic.hpp
index ff0d83a..c3d5a5f 100644
--- a/include/generic.hpp
+++ b/include/generic.hpp
@@ -175,6 +175,11 @@ static const std::unordered_map<pgfe_algorithm_choice, size_t> pgfe_block_length
     {RawSHAKE256, PGFE_RawSHAKE256_BLOCK_SIZE},
 };
 
+// String to algorithm choice type
+
+pgfe_algorithm_choice string_to_algorithm_choice(const char *cs);
+pgfe_algorithm_choice string_to_algorithm_choice(std::string cpp_s);
+
 } // namespace PGFE
 } // namespace chardon55
 
diff --git a/include/utils.hpp b/include/utils.hpp
index aa54e55..5019061 100644
--- a/include/utils.hpp
+++ b/include/utils.hpp
@@ -28,9 +28,6 @@ SequentialData *to_sequential_data(const pgfe_encode_t *pgfe_c_seq, size_t);
 SequentialData *to_sequential_data(const char *cs);
 SequentialData *to_sequential_data(std::string &);
 
-pgfe_algorithm_choice string_to_algorithm_choice(const char *cs);
-pgfe_algorithm_choice string_to_algorithm_choice(std::string cpp_s);
-
 namespace sequential_data {
 
 SequentialData *from_hex_string(const char *hex_cs);
diff --git a/src/generic.cpp b/src/generic.cpp
new file mode 100644
index 0000000..97821d6
--- /dev/null
+++ b/src/generic.cpp
@@ -0,0 +1,23 @@
+#ifndef LIBPGFE_GENERIC_CPP
+#define LIBPGFE_GENERIC_CPP
+
+#include "generic.hpp"
+
+#include "generic.h"
+
+namespace chardon55 {
+namespace PGFE {
+
+pgfe_algorithm_choice string_to_algorithm_choice(const char *cs) {
+    std::string s{cs};
+    return string_to_algorithm_choice(s);
+}
+
+pgfe_algorithm_choice string_to_algorithm_choice(std::string cpp_s) {
+    return pgfe_option_map.at(cpp_s);
+}
+
+} // namespace PGFE
+} // namespace chardon55
+
+#endif
\ No newline at end of file
diff --git a/src/sequential_data.cpp b/src/sequential_data.cpp
index 4dd426b..b030668 100644
--- a/src/sequential_data.cpp
+++ b/src/sequential_data.cpp
@@ -12,9 +12,7 @@
 using namespace chardon55::PGFE;
 
 SequentialData::~SequentialData() {
-    if (seq) {
-        delete[] seq;
-    }
+    delete[] seq;
 
     if (hex_str) {
         delete[] hex_str;
diff --git a/src/utils.cpp b/src/utils.cpp
index 10ab468..c03e377 100644
--- a/src/utils.cpp
+++ b/src/utils.cpp
@@ -41,15 +41,6 @@ SequentialData *sequential_data::from_hex_string(std::string &hex_cpps) {
     return from_hex_string(hex_cpps.c_str());
 }
 
-pgfe_algorithm_choice string_to_algorithm_choice(const char *cs) {
-    std::string s{cs};
-    return string_to_algorithm_choice(s);
-}
-
-pgfe_algorithm_choice string_to_algorithm_choice(std::string cpp_s) {
-    return pgfe_option_map.at(cpp_s);
-}
-
 } // namespace utils
 } // namespace PGFE
 } // namespace chardon55
\ No newline at end of file
diff --git a/test/hmactest.hpp b/test/hmactest.hpp
index 418f276..4c57329 100644
--- a/test/hmactest.hpp
+++ b/test/hmactest.hpp
@@ -13,7 +13,6 @@
 
 void hmac_encoder_test(ARGS) {
     USE_PGFE_CPP
-    USE_PGFE_CPP_UTILS
 
     HMACEncoder *encoder;
 

From 2c192d9c846dfdde2984c9688467ee7c5ff6ed64 Mon Sep 17 00:00:00 2001
From: chardon55 <charlesdong_2000@outlook.com>
Date: Sun, 30 Oct 2022 11:22:03 +0800
Subject: [PATCH 09/22] Add disposal code

---
 src/sha2-backend.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/src/sha2-backend.c b/src/sha2-backend.c
index 59e4179..8f97a79 100644
--- a/src/sha2-backend.c
+++ b/src/sha2-backend.c
@@ -70,6 +70,10 @@ void __pgfe_sha256_process_block(struct pgfe_sha256_ctx *ctx) {
     ctx->state[7] += H;
 
     ctx->index = 0;
+
+    // Wipe data from RAM
+    tmp1 = tmp2 = A = B = C = D = E = F = G = H = 0;
+    memset(ws, 0, PGFE_SHA256_BLOCK_SIZE);
 }
 
 void __pgfe_sha224n256_padding(struct pgfe_sha256_ctx *ctx) {

From b53159459bd96f5e974db541b8cf5972ac66eaf2 Mon Sep 17 00:00:00 2001
From: chardon55 <charlesdong_2000@outlook.com>
Date: Sun, 30 Oct 2022 11:22:08 +0800
Subject: [PATCH 10/22] Refactoring

---
 src/sha224.c | 4 ++--
 src/sha256.c | 4 ++--
 2 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/src/sha224.c b/src/sha224.c
index 028ab85..d8af317 100644
--- a/src/sha224.c
+++ b/src/sha224.c
@@ -13,8 +13,8 @@
 const pgfe_word_t __pgfe_sha224_H0[] = {0xC1059ED8, 0x367CD507, 0x3070DD17, 0xF70E5939,
                                         0xFFC00B31, 0x68581511, 0x64F98FA7, 0xBEFA4FA4};
 
-__PGFE_FRONTEND_GEN2(sha224);
-__PGFE_FRONTEND_DEFAULT_GEN2(sha224, SHA224);
+__PGFE_FRONTEND_GEN2(sha224)
+__PGFE_FRONTEND_DEFAULT_GEN2(sha224, SHA224)
 
 __PGFE_SHA_INIT(sha224)
 __PGFE_SHA_UPDATE(sha224, SHA224)
diff --git a/src/sha256.c b/src/sha256.c
index 3bfa704..b4bf57a 100644
--- a/src/sha256.c
+++ b/src/sha256.c
@@ -12,8 +12,8 @@
 const pgfe_word_t __pgfe_sha256_H0[] = {0x6A09E667, 0xBB67AE85, 0x3C6EF372, 0xA54FF53A,
                                         0x510E527F, 0x9B05688C, 0x1F83D9AB, 0x5BE0CD19};
 
-__PGFE_FRONTEND_GEN2(sha256);
-__PGFE_FRONTEND_DEFAULT_GEN2(sha256, SHA256);
+__PGFE_FRONTEND_GEN2(sha256)
+__PGFE_FRONTEND_DEFAULT_GEN2(sha256, SHA256)
 
 __PGFE_SHA_INIT(sha256)
 __PGFE_SHA_UPDATE(sha256, SHA256)

From 8cb821f2ad23b59f6d8b0d74f364bb0226801467 Mon Sep 17 00:00:00 2001
From: chardon55 <charlesdong_2000@outlook.com>
Date: Sun, 30 Oct 2022 12:18:09 +0800
Subject: [PATCH 11/22] Update file structure

---
 CMakeLists.txt                                | 57 +++++++++----------
 .../{ => backend}/base-encoding-internal.h    |  2 +-
 include/{ => backend}/generic-internal.h      |  2 +-
 include/{ => backend}/keccak-backend.h        |  0
 include/{ => backend}/md5-backend.h           |  0
 include/{ => backend}/otp-generic.h           |  4 +-
 include/{ => backend}/sha-internal.h          |  0
 include/{ => backend}/sha2-backend.h          |  3 +-
 .../backend/templates.h                       |  6 +-
 .../abstract_base_encoding.hpp                |  4 +-
 .../{ => backend_cpp}/abstract_encoder.hpp    |  6 +-
 .../abstract_hash_encoder.hpp                 |  9 +--
 include/{ => backend_cpp}/abstract_otp.hpp    |  8 +--
 include/base16.hpp                            |  2 +-
 include/base32.hpp                            |  2 +-
 include/base64.hpp                            |  2 +-
 include/hash_encoder.hpp                      |  2 +-
 include/hmac.h                                |  2 +-
 include/hmac_encoder.hpp                      |  2 +-
 include/hotp.h                                |  4 +-
 include/hotp.hpp                              |  2 +-
 include/md5.h                                 |  2 +-
 include/sha1.h                                |  2 +-
 include/sha2.h                                |  2 +-
 include/sha3.h                                |  2 +-
 include/totp.h                                |  2 +-
 include/utils.h                               |  2 +-
 .../base_encoding}/base-encoding-internal.c   |  4 +-
 src/{ => c/base_encoding}/base16.c            |  2 +-
 src/{ => c/base_encoding}/base32.c            |  4 +-
 src/{ => c/base_encoding}/base64.c            |  2 +-
 src/{ => c}/generic-internal.c                |  2 +-
 src/{ => c}/generic.c                         |  0
 src/{ => c/hash}/keccak-backend.c             |  2 +-
 src/{ => c/hash}/md5-backend.c                |  2 +-
 src/{ => c/hash}/md5.c                        |  4 +-
 src/{ => c/hash}/sha-internal.c               |  2 +-
 src/{ => c/hash}/sha1.c                       |  6 +-
 src/{ => c/hash}/sha2-backend.c               |  5 +-
 src/{ => c/hash}/sha224.c                     |  4 +-
 src/{ => c/hash}/sha256.c                     |  5 +-
 src/{ => c/hash}/sha3-224.c                   |  3 +-
 src/{ => c/hash}/sha3-256.c                   |  3 +-
 src/{ => c/hash}/sha3-384.c                   |  3 +-
 src/{ => c/hash}/sha3-512.c                   |  3 +-
 src/{ => c/hash}/sha384.c                     |  4 +-
 src/{ => c/hash}/sha512.c                     |  4 +-
 src/{ => c/hash}/shake.c                      |  2 +-
 src/{ => c/hmac}/hmac.c                       |  2 +-
 src/{ => c/otp}/hotp.c                        |  2 +-
 src/{ => c/otp}/otp-generic.c                 |  2 +-
 src/{ => c/otp}/totp.c                        |  2 +-
 src/{ => c}/utils.c                           |  2 +-
 src/{ => cpp}/algorithm_selectable.cpp        |  0
 .../base_encoding}/abstract_base_encoding.cpp |  2 +-
 src/{ => cpp/base_encoding}/base16.cpp        |  0
 src/{ => cpp/base_encoding}/base32.cpp        |  0
 src/{ => cpp/base_encoding}/base64.cpp        |  0
 src/{ => cpp}/generic.cpp                     |  0
 src/{ => cpp/hash}/hash_encoder.cpp           |  0
 src/{ => cpp/hmac}/hmac_encoder.cpp           |  0
 src/{ => cpp/otp}/abstract_otp.cpp            |  2 +-
 src/{ => cpp/otp}/hotp.cpp                    |  0
 src/{ => cpp/otp}/totp.cpp                    |  0
 src/{ => cpp}/sequential_data.cpp             |  0
 src/{ => cpp}/utils.cpp                       |  0
 66 files changed, 109 insertions(+), 102 deletions(-)
 rename include/{ => backend}/base-encoding-internal.h (98%)
 rename include/{ => backend}/generic-internal.h (99%)
 rename include/{ => backend}/keccak-backend.h (100%)
 rename include/{ => backend}/md5-backend.h (100%)
 rename include/{ => backend}/otp-generic.h (92%)
 rename include/{ => backend}/sha-internal.h (100%)
 rename include/{ => backend}/sha2-backend.h (98%)
 rename src/templates.c => include/backend/templates.h (99%)
 rename include/{ => backend_cpp}/abstract_base_encoding.hpp (96%)
 rename include/{ => backend_cpp}/abstract_encoder.hpp (92%)
 rename include/{ => backend_cpp}/abstract_hash_encoder.hpp (84%)
 rename include/{ => backend_cpp}/abstract_otp.hpp (85%)
 rename src/{ => c/base_encoding}/base-encoding-internal.c (98%)
 rename src/{ => c/base_encoding}/base16.c (95%)
 rename src/{ => c/base_encoding}/base32.c (96%)
 rename src/{ => c/base_encoding}/base64.c (97%)
 rename src/{ => c}/generic-internal.c (96%)
 rename src/{ => c}/generic.c (100%)
 rename src/{ => c/hash}/keccak-backend.c (99%)
 rename src/{ => c/hash}/md5-backend.c (99%)
 rename src/{ => c/hash}/md5.c (96%)
 rename src/{ => c/hash}/sha-internal.c (66%)
 rename src/{ => c/hash}/sha1.c (96%)
 rename src/{ => c/hash}/sha2-backend.c (99%)
 rename src/{ => c/hash}/sha224.c (89%)
 rename src/{ => c/hash}/sha256.c (89%)
 rename src/{ => c/hash}/sha3-224.c (95%)
 rename src/{ => c/hash}/sha3-256.c (95%)
 rename src/{ => c/hash}/sha3-384.c (95%)
 rename src/{ => c/hash}/sha3-512.c (95%)
 rename src/{ => c/hash}/sha384.c (93%)
 rename src/{ => c/hash}/sha512.c (97%)
 rename src/{ => c/hash}/shake.c (98%)
 rename src/{ => c/hmac}/hmac.c (99%)
 rename src/{ => c/otp}/hotp.c (98%)
 rename src/{ => c/otp}/otp-generic.c (92%)
 rename src/{ => c/otp}/totp.c (98%)
 rename src/{ => c}/utils.c (98%)
 rename src/{ => cpp}/algorithm_selectable.cpp (100%)
 rename src/{ => cpp/base_encoding}/abstract_base_encoding.cpp (98%)
 rename src/{ => cpp/base_encoding}/base16.cpp (100%)
 rename src/{ => cpp/base_encoding}/base32.cpp (100%)
 rename src/{ => cpp/base_encoding}/base64.cpp (100%)
 rename src/{ => cpp}/generic.cpp (100%)
 rename src/{ => cpp/hash}/hash_encoder.cpp (100%)
 rename src/{ => cpp/hmac}/hmac_encoder.cpp (100%)
 rename src/{ => cpp/otp}/abstract_otp.cpp (94%)
 rename src/{ => cpp/otp}/hotp.cpp (100%)
 rename src/{ => cpp/otp}/totp.cpp (100%)
 rename src/{ => cpp}/sequential_data.cpp (100%)
 rename src/{ => cpp}/utils.cpp (100%)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 0fb32bf..d82f6cc 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -16,35 +16,34 @@ set(include_dir "include")
 set(test_dir "test")
 
 add_library(pgfe SHARED 
-    ${src_dir}/generic.c 
-    ${src_dir}/generic-internal.c
-    ${src_dir}/templates.c
-    ${src_dir}/utils.c
-    ${src_dir}/sha-internal.c
-    ${src_dir}/sha2-backend.c
-    ${src_dir}/keccak-backend.c
-    ${src_dir}/md5-backend.c
-    ${src_dir}/sha1.c ${src_dir}/sha224.c ${src_dir}/sha256.c ${src_dir}/sha384.c ${src_dir}/sha512.c
-    ${src_dir}/sha3-224.c ${src_dir}/sha3-256.c ${src_dir}/sha3-384.c ${src_dir}/sha3-512.c 
-    ${src_dir}/md5.c 
-    ${src_dir}/shake.c
-    ${src_dir}/hmac.c
-    ${src_dir}/otp-generic.c
-    ${src_dir}/hotp.c ${src_dir}/totp.c
-    ${src_dir}/base-encoding-internal.c
-    ${src_dir}/base64.c ${src_dir}/base32.c ${src_dir}/base16.c
-    ${src_dir}/generic.cpp
-    ${src_dir}/sequential_data.cpp
-    ${src_dir}/utils.cpp
-    ${src_dir}/algorithm_selectable.cpp
-    ${src_dir}/hash_encoder.cpp
-    ${src_dir}/hmac_encoder.cpp
-    ${src_dir}/abstract_base_encoding.cpp
-    ${src_dir}/base16.cpp
-    ${src_dir}/base32.cpp
-    ${src_dir}/base64.cpp
-    ${src_dir}/abstract_otp.cpp
-    ${src_dir}/hotp.cpp ${src_dir}/totp.cpp)
+    ${src_dir}/c/generic.c 
+    ${src_dir}/c/generic-internal.c
+    ${src_dir}/c/utils.c
+    ${src_dir}/c/hash/sha-internal.c
+    ${src_dir}/c/hash/sha2-backend.c
+    ${src_dir}/c/hash/keccak-backend.c
+    ${src_dir}/c/hash/md5-backend.c
+    ${src_dir}/c/hash/sha1.c ${src_dir}/c/hash/sha224.c ${src_dir}/c/hash/sha256.c ${src_dir}/c/hash/sha384.c ${src_dir}/c/hash/sha512.c
+    ${src_dir}/c/hash/sha3-224.c ${src_dir}/c/hash/sha3-256.c ${src_dir}/c/hash/sha3-384.c ${src_dir}/c/hash/sha3-512.c 
+    ${src_dir}/c/hash/md5.c 
+    ${src_dir}/c/hash/shake.c
+    ${src_dir}/c/hmac/hmac.c
+    ${src_dir}/c/otp/otp-generic.c
+    ${src_dir}/c/otp/hotp.c ${src_dir}/c/otp/totp.c
+    ${src_dir}/c/base_encoding/base-encoding-internal.c
+    ${src_dir}/c/base_encoding/base64.c ${src_dir}/c/base_encoding/base32.c ${src_dir}/c/base_encoding/base16.c
+    ${src_dir}/cpp/generic.cpp
+    ${src_dir}/cpp/sequential_data.cpp
+    ${src_dir}/cpp/utils.cpp
+    ${src_dir}/cpp/algorithm_selectable.cpp
+    ${src_dir}/cpp/hash/hash_encoder.cpp
+    ${src_dir}/cpp/hmac/hmac_encoder.cpp
+    ${src_dir}/cpp/base_encoding/abstract_base_encoding.cpp
+    ${src_dir}/cpp/base_encoding/base16.cpp
+    ${src_dir}/cpp/base_encoding/base32.cpp
+    ${src_dir}/cpp/base_encoding/base64.cpp
+    ${src_dir}/cpp/otp/abstract_otp.cpp
+    ${src_dir}/cpp/otp/hotp.cpp ${src_dir}/cpp/otp/totp.cpp)
 add_executable(pgfetest ${test_dir}/test.c)
 # add_executable(totptest ${test_dir}/totptest.c)
 # add_executable(totptestcpp ${test_dir}/totptest.cpp)
diff --git a/include/base-encoding-internal.h b/include/backend/base-encoding-internal.h
similarity index 98%
rename from include/base-encoding-internal.h
rename to include/backend/base-encoding-internal.h
index 6a7852c..ccee40d 100644
--- a/include/base-encoding-internal.h
+++ b/include/backend/base-encoding-internal.h
@@ -10,7 +10,7 @@
 
 #include <stdbool.h>
 
-#include "generic.h"
+#include "../generic.h"
 
 #ifdef __cplusplus
 extern "C" {
diff --git a/include/generic-internal.h b/include/backend/generic-internal.h
similarity index 99%
rename from include/generic-internal.h
rename to include/backend/generic-internal.h
index f852841..018460a 100644
--- a/include/generic-internal.h
+++ b/include/backend/generic-internal.h
@@ -8,7 +8,7 @@
 #ifndef LIBPGFE_GENERIC_INTERNAL_H
 #define LIBPGFE_GENERIC_INTERNAL_H
 
-#include "generic.h"
+#include "../generic.h"
 
 #ifdef __cplusplus
 extern "C" {
diff --git a/include/keccak-backend.h b/include/backend/keccak-backend.h
similarity index 100%
rename from include/keccak-backend.h
rename to include/backend/keccak-backend.h
diff --git a/include/md5-backend.h b/include/backend/md5-backend.h
similarity index 100%
rename from include/md5-backend.h
rename to include/backend/md5-backend.h
diff --git a/include/otp-generic.h b/include/backend/otp-generic.h
similarity index 92%
rename from include/otp-generic.h
rename to include/backend/otp-generic.h
index 75109c3..172deaf 100644
--- a/include/otp-generic.h
+++ b/include/backend/otp-generic.h
@@ -10,8 +10,8 @@
 
 #include <stdint.h>
 
-#include "generic.h"
-#include "hmac.h"
+#include "../generic.h"
+#include "../hmac.h"
 
 #ifdef __cplusplus
 extern "C" {
diff --git a/include/sha-internal.h b/include/backend/sha-internal.h
similarity index 100%
rename from include/sha-internal.h
rename to include/backend/sha-internal.h
diff --git a/include/sha2-backend.h b/include/backend/sha2-backend.h
similarity index 98%
rename from include/sha2-backend.h
rename to include/backend/sha2-backend.h
index 453dc38..426ef63 100644
--- a/include/sha2-backend.h
+++ b/include/backend/sha2-backend.h
@@ -9,7 +9,8 @@
 #define LIBPGFE_SHA2_INTERNAL_H
 
 #include "sha-internal.h"
-#include "sha2.h"
+
+#include "../sha2.h"
 
 #ifdef __cpluslpus
 extern "C" {
diff --git a/src/templates.c b/include/backend/templates.h
similarity index 99%
rename from src/templates.c
rename to include/backend/templates.h
index e5068d2..a440108 100644
--- a/src/templates.c
+++ b/include/backend/templates.h
@@ -1,12 +1,12 @@
 /*
   libpgfe
-  templates.c
+  templates.h
 
   Copyright (c) 2022 Charles Dong
 */
 
-#ifndef LIBPGFE_TEMPLATES_C
-#define LIBPGFE_TEMPLATES_C
+#ifndef LIBPGFE_TEMPLATES_H
+#define LIBPGFE_TEMPLATES_H
 
 #ifdef __cplusplus
 extern "C" {
diff --git a/include/abstract_base_encoding.hpp b/include/backend_cpp/abstract_base_encoding.hpp
similarity index 96%
rename from include/abstract_base_encoding.hpp
rename to include/backend_cpp/abstract_base_encoding.hpp
index 4a9790e..9f36b3d 100644
--- a/include/abstract_base_encoding.hpp
+++ b/include/backend_cpp/abstract_base_encoding.hpp
@@ -14,8 +14,8 @@
 #include <mutex>
 #include <string>
 
-#include "generic.h"
-#include "sequential_data.hpp"
+#include "../generic.h"
+#include "../sequential_data.hpp"
 
 namespace chardon55 {
 namespace PGFE {
diff --git a/include/abstract_encoder.hpp b/include/backend_cpp/abstract_encoder.hpp
similarity index 92%
rename from include/abstract_encoder.hpp
rename to include/backend_cpp/abstract_encoder.hpp
index 3ed552c..80b1334 100644
--- a/include/abstract_encoder.hpp
+++ b/include/backend_cpp/abstract_encoder.hpp
@@ -14,9 +14,9 @@
 #include <cstring>
 #include <string>
 
-#include "generic.h"
-#include "sequential_data.hpp"
-#include "utils.hpp"
+#include "../generic.h"
+#include "../sequential_data.hpp"
+#include "../utils.hpp"
 
 namespace chardon55 {
 namespace PGFE {
diff --git a/include/abstract_hash_encoder.hpp b/include/backend_cpp/abstract_hash_encoder.hpp
similarity index 84%
rename from include/abstract_hash_encoder.hpp
rename to include/backend_cpp/abstract_hash_encoder.hpp
index 4d9f29b..83bcfbf 100644
--- a/include/abstract_hash_encoder.hpp
+++ b/include/backend_cpp/abstract_hash_encoder.hpp
@@ -14,10 +14,11 @@
 #include <string>
 
 #include "abstract_encoder.hpp"
-#include "algorithm-choice.h"
-#include "algorithm_selectable.hpp"
-#include "generic.h"
-#include "generic.hpp"
+
+#include "../algorithm-choice.h"
+#include "../algorithm_selectable.hpp"
+#include "../generic.h"
+#include "../generic.hpp"
 
 namespace chardon55 {
 namespace PGFE {
diff --git a/include/abstract_otp.hpp b/include/backend_cpp/abstract_otp.hpp
similarity index 85%
rename from include/abstract_otp.hpp
rename to include/backend_cpp/abstract_otp.hpp
index 79c51ac..1720b87 100644
--- a/include/abstract_otp.hpp
+++ b/include/backend_cpp/abstract_otp.hpp
@@ -13,10 +13,10 @@
 
 #include <string>
 
-#include "algorithm_selectable.hpp"
-#include "generic.h"
-#include "otp-generic.h"
-#include "sequential_data.hpp"
+#include "../algorithm_selectable.hpp"
+#include "../backend/otp-generic.h"
+#include "../generic.h"
+#include "../sequential_data.hpp"
 
 namespace chardon55 {
 namespace PGFE {
diff --git a/include/base16.hpp b/include/base16.hpp
index 915bbca..4038085 100644
--- a/include/base16.hpp
+++ b/include/base16.hpp
@@ -11,7 +11,7 @@
 #error libpgfe error: C++ headers are not compatible with C source
 #endif
 
-#include "abstract_base_encoding.hpp"
+#include "backend_cpp/abstract_base_encoding.hpp"
 
 namespace chardon55 {
 namespace PGFE {
diff --git a/include/base32.hpp b/include/base32.hpp
index 01a7eeb..c55ce70 100644
--- a/include/base32.hpp
+++ b/include/base32.hpp
@@ -11,7 +11,7 @@
 #error libpgfe error: C++ headers are not compatible with C source
 #endif
 
-#include "abstract_base_encoding.hpp"
+#include "backend_cpp/abstract_base_encoding.hpp"
 
 namespace chardon55 {
 namespace PGFE {
diff --git a/include/base64.hpp b/include/base64.hpp
index dc01fb6..6f4b2cd 100644
--- a/include/base64.hpp
+++ b/include/base64.hpp
@@ -11,7 +11,7 @@
 #error libpgfe error: C++ headers are not compatible with C source
 #endif
 
-#include "abstract_base_encoding.hpp"
+#include "backend_cpp/abstract_base_encoding.hpp"
 
 namespace chardon55 {
 namespace PGFE {
diff --git a/include/hash_encoder.hpp b/include/hash_encoder.hpp
index 3dd5f42..04b657e 100644
--- a/include/hash_encoder.hpp
+++ b/include/hash_encoder.hpp
@@ -11,7 +11,7 @@
 #error libpgfe error: C++ headers are not compatible with C source
 #endif
 
-#include "abstract_hash_encoder.hpp"
+#include "backend_cpp/abstract_hash_encoder.hpp"
 
 #include "generic.hpp"
 
diff --git a/include/hmac.h b/include/hmac.h
index ce5cd4f..e5e9f17 100644
--- a/include/hmac.h
+++ b/include/hmac.h
@@ -8,7 +8,7 @@
 #ifndef LIBPGFE_HMAC_H
 #define LIBPGFE_HMAC_H
 
-#include "generic-internal.h"
+#include "backend/generic-internal.h"
 #include "generic.h"
 #include "md5.h"
 #include "sha1.h"
diff --git a/include/hmac_encoder.hpp b/include/hmac_encoder.hpp
index 521ad71..128023c 100644
--- a/include/hmac_encoder.hpp
+++ b/include/hmac_encoder.hpp
@@ -13,7 +13,7 @@
 
 #include <vector>
 
-#include "abstract_hash_encoder.hpp"
+#include "backend_cpp/abstract_hash_encoder.hpp"
 #include "generic.h"
 #include "generic.hpp"
 #include "hmac.h"
diff --git a/include/hotp.h b/include/hotp.h
index 8546ac1..717dcc4 100644
--- a/include/hotp.h
+++ b/include/hotp.h
@@ -8,8 +8,8 @@
 #ifndef LIBPGFE_HOTP_H
 #define LIBPGFE_HOTP_H
 
-#include "generic-internal.h"
-#include "otp-generic.h"
+#include "backend/generic-internal.h"
+#include "backend/otp-generic.h"
 
 #ifdef __cplusplus
 extern "C" {
diff --git a/include/hotp.hpp b/include/hotp.hpp
index fb594ff..85eb81b 100644
--- a/include/hotp.hpp
+++ b/include/hotp.hpp
@@ -11,7 +11,7 @@
 #error libpgfe error: C++ headers are not compatible with C source
 #endif
 
-#include "abstract_otp.hpp"
+#include "backend_cpp/abstract_otp.hpp"
 #include "base32.hpp"
 
 namespace chardon55 {
diff --git a/include/md5.h b/include/md5.h
index a69cafa..68ac42f 100644
--- a/include/md5.h
+++ b/include/md5.h
@@ -10,7 +10,7 @@
 
 #include <stdio.h>
 
-#include "generic-internal.h"
+#include "backend/generic-internal.h"
 #include "generic.h"
 
 #ifdef __cplusplus
diff --git a/include/sha1.h b/include/sha1.h
index 7a7a640..1e93ce8 100644
--- a/include/sha1.h
+++ b/include/sha1.h
@@ -10,7 +10,7 @@
 
 #include <stdio.h>
 
-#include "generic-internal.h"
+#include "backend/generic-internal.h"
 
 #ifdef __cplusplus
 extern "C" {
diff --git a/include/sha2.h b/include/sha2.h
index bcf245f..cc5a242 100644
--- a/include/sha2.h
+++ b/include/sha2.h
@@ -10,7 +10,7 @@
 
 #include <stdio.h>
 
-#include "generic-internal.h"
+#include "backend/generic-internal.h"
 
 #ifdef __cplusplus
 extern "C" {
diff --git a/include/sha3.h b/include/sha3.h
index 7c97271..23d24c7 100644
--- a/include/sha3.h
+++ b/include/sha3.h
@@ -10,8 +10,8 @@
 
 #include <stdio.h>
 
+#include "backend/keccak-backend.h"
 #include "generic.h"
-#include "keccak-backend.h"
 
 #ifdef __cplusplus
 extern "C" {
diff --git a/include/totp.h b/include/totp.h
index ab88a03..ae469dd 100644
--- a/include/totp.h
+++ b/include/totp.h
@@ -9,7 +9,7 @@
 #ifndef LIBPGFE_TOTP_H
 #define LIBPGFE_TOTP_H
 
-#include "otp-generic.h"
+#include "backend/otp-generic.h"
 
 #ifdef __cplusplus
 extern "C" {
diff --git a/include/utils.h b/include/utils.h
index d461696..65dadf1 100644
--- a/include/utils.h
+++ b/include/utils.h
@@ -8,8 +8,8 @@
 #ifndef LIBPGFE_UTILS_H
 #define LIBPGFE_UTILS_H
 
+#include "backend/otp-generic.h"
 #include "generic.h"
-#include "otp-generic.h"
 
 #include <time.h>
 
diff --git a/src/base-encoding-internal.c b/src/c/base_encoding/base-encoding-internal.c
similarity index 98%
rename from src/base-encoding-internal.c
rename to src/c/base_encoding/base-encoding-internal.c
index c5e8bb9..12880ea 100644
--- a/src/base-encoding-internal.c
+++ b/src/c/base_encoding/base-encoding-internal.c
@@ -5,11 +5,11 @@
   Copyright (c) 2022 Charles Dong
 */
 
-#include "base-encoding-internal.h"
+#include "backend/base-encoding-internal.h"
 
 #include <limits.h>
 
-#include "generic-internal.h"
+#include "backend/generic-internal.h"
 
 uint8_t __pgfe_build_mask(uint8_t digit_c);
 
diff --git a/src/base16.c b/src/c/base_encoding/base16.c
similarity index 95%
rename from src/base16.c
rename to src/c/base_encoding/base16.c
index c3460f5..46fba76 100644
--- a/src/base16.c
+++ b/src/c/base_encoding/base16.c
@@ -7,7 +7,7 @@
 
 #include "base-encoding.h"
 
-#include "base-encoding-internal.h"
+#include "backend/base-encoding-internal.h"
 
 // Base 16 alphabet
 const char BASE16_ALPHABET[] = "0123456789ABCDEF"
diff --git a/src/base32.c b/src/c/base_encoding/base32.c
similarity index 96%
rename from src/base32.c
rename to src/c/base_encoding/base32.c
index 25c7a18..197f8f3 100644
--- a/src/base32.c
+++ b/src/c/base_encoding/base32.c
@@ -9,8 +9,8 @@
 
 #include <string.h>
 
-#include "base-encoding-internal.h"
-#include "generic-internal.h"
+#include "backend/base-encoding-internal.h"
+#include "backend/generic-internal.h"
 
 // Base 32 alphabet
 //                              0123456789ABCDEF
diff --git a/src/base64.c b/src/c/base_encoding/base64.c
similarity index 97%
rename from src/base64.c
rename to src/c/base_encoding/base64.c
index 992b224..086332a 100644
--- a/src/base64.c
+++ b/src/c/base_encoding/base64.c
@@ -9,7 +9,7 @@
 
 #include <string.h>
 
-#include "base-encoding-internal.h"
+#include "backend/base-encoding-internal.h"
 
 // Base 64 alphabet
 //                              0123456789ABCDEF
diff --git a/src/generic-internal.c b/src/c/generic-internal.c
similarity index 96%
rename from src/generic-internal.c
rename to src/c/generic-internal.c
index aa5b261..c78cdab 100644
--- a/src/generic-internal.c
+++ b/src/c/generic-internal.c
@@ -5,7 +5,7 @@
   Copyright (c) 2022 Charles Dong
 */
 
-#include "generic-internal.h"
+#include "backend/generic-internal.h"
 
 inline void __pgfe_arrinit(pgfe_encode_t arr[], size_t size) {
     for (int i = 0; i < size; i++) {
diff --git a/src/generic.c b/src/c/generic.c
similarity index 100%
rename from src/generic.c
rename to src/c/generic.c
diff --git a/src/keccak-backend.c b/src/c/hash/keccak-backend.c
similarity index 99%
rename from src/keccak-backend.c
rename to src/c/hash/keccak-backend.c
index 3c643cc..4134b3c 100644
--- a/src/keccak-backend.c
+++ b/src/c/hash/keccak-backend.c
@@ -5,7 +5,7 @@
   Copyright (c) 2022 Charles Dong
 */
 
-#include "keccak-backend.h"
+#include "backend/keccak-backend.h"
 
 #include <stdlib.h>
 #include <string.h>
diff --git a/src/md5-backend.c b/src/c/hash/md5-backend.c
similarity index 99%
rename from src/md5-backend.c
rename to src/c/hash/md5-backend.c
index f982a52..2e32304 100644
--- a/src/md5-backend.c
+++ b/src/c/hash/md5-backend.c
@@ -5,7 +5,7 @@
   Copyright (c) 2022 Charles Dong
 */
 
-#include "md5-backend.h"
+#include "backend/md5-backend.h"
 
 #include <string.h>
 
diff --git a/src/md5.c b/src/c/hash/md5.c
similarity index 96%
rename from src/md5.c
rename to src/c/hash/md5.c
index ba58c95..86c397a 100644
--- a/src/md5.c
+++ b/src/c/hash/md5.c
@@ -9,8 +9,8 @@
 
 #include <string.h>
 
-#include "md5-backend.h"
-#include "templates.c"
+#include "backend/md5-backend.h"
+#include "backend/templates.h"
 
 __PGFE_FRONTEND_GEN2(md5);
 __PGFE_FRONTEND_DEFAULT_GEN2(md5, MD5);
diff --git a/src/sha-internal.c b/src/c/hash/sha-internal.c
similarity index 66%
rename from src/sha-internal.c
rename to src/c/hash/sha-internal.c
index e53ff61..f45f646 100644
--- a/src/sha-internal.c
+++ b/src/c/hash/sha-internal.c
@@ -5,4 +5,4 @@
   Copyright (c) 2022 Charles Dong
 */
 
-#include "sha-internal.h"
+#include "backend/sha-internal.h"
diff --git a/src/sha1.c b/src/c/hash/sha1.c
similarity index 96%
rename from src/sha1.c
rename to src/c/hash/sha1.c
index f5617ce..fe13d7c 100644
--- a/src/sha1.c
+++ b/src/c/hash/sha1.c
@@ -7,9 +7,9 @@
 
 #include "sha1.h"
 
-#include "generic-internal.h"
-#include "sha-internal.h"
-#include "templates.c"
+#include "backend/generic-internal.h"
+#include "backend/sha-internal.h"
+#include "backend/templates.h"
 
 const pgfe_word_t __pgfe_sha1_H0[] = {0x67452301, 0xEFCDAB89, 0x98BADCFE, 0x10325476, 0xC3D2E1F0};
 
diff --git a/src/sha2-backend.c b/src/c/hash/sha2-backend.c
similarity index 99%
rename from src/sha2-backend.c
rename to src/c/hash/sha2-backend.c
index 8f97a79..8c8d42f 100644
--- a/src/sha2-backend.c
+++ b/src/c/hash/sha2-backend.c
@@ -5,9 +5,10 @@
   Copyright (c) 2022 Charles Dong
 */
 
-#include "sha2-backend.h"
+#include "backend/sha2-backend.h"
+
+#include "backend/templates.h"
 #include "sha2.h"
-#include "templates.c"
 
 #include <string.h>
 
diff --git a/src/sha224.c b/src/c/hash/sha224.c
similarity index 89%
rename from src/sha224.c
rename to src/c/hash/sha224.c
index d8af317..e1d4cde 100644
--- a/src/sha224.c
+++ b/src/c/hash/sha224.c
@@ -7,8 +7,8 @@
 
 #include "sha2.h"
 
-#include "sha2-backend.h"
-#include "templates.c"
+#include "backend/sha2-backend.h"
+#include "backend/templates.h"
 
 const pgfe_word_t __pgfe_sha224_H0[] = {0xC1059ED8, 0x367CD507, 0x3070DD17, 0xF70E5939,
                                         0xFFC00B31, 0x68581511, 0x64F98FA7, 0xBEFA4FA4};
diff --git a/src/sha256.c b/src/c/hash/sha256.c
similarity index 89%
rename from src/sha256.c
rename to src/c/hash/sha256.c
index b4bf57a..27f35af 100644
--- a/src/sha256.c
+++ b/src/c/hash/sha256.c
@@ -5,9 +5,10 @@
   Copyright (c) 2022 Charles Dong
 */
 
-#include "sha2-backend.h"
 #include "sha2.h"
-#include "templates.c"
+
+#include "backend/sha2-backend.h"
+#include "backend/templates.h"
 
 const pgfe_word_t __pgfe_sha256_H0[] = {0x6A09E667, 0xBB67AE85, 0x3C6EF372, 0xA54FF53A,
                                         0x510E527F, 0x9B05688C, 0x1F83D9AB, 0x5BE0CD19};
diff --git a/src/sha3-224.c b/src/c/hash/sha3-224.c
similarity index 95%
rename from src/sha3-224.c
rename to src/c/hash/sha3-224.c
index 8ce2d81..8e8ec44 100644
--- a/src/sha3-224.c
+++ b/src/c/hash/sha3-224.c
@@ -6,7 +6,8 @@
 */
 
 #include "sha3.h"
-#include "templates.c"
+
+#include "backend/templates.h"
 
 __PGFE_FRONTEND_GEN2(sha3_224);
 __PGFE_FRONTEND_DEFAULT_GEN2(sha3_224, SHA3_224);
diff --git a/src/sha3-256.c b/src/c/hash/sha3-256.c
similarity index 95%
rename from src/sha3-256.c
rename to src/c/hash/sha3-256.c
index 707449a..f34a1da 100644
--- a/src/sha3-256.c
+++ b/src/c/hash/sha3-256.c
@@ -6,7 +6,8 @@
 */
 
 #include "sha3.h"
-#include "templates.c"
+
+#include "backend/templates.h"
 
 __PGFE_FRONTEND_GEN2(sha3_256);
 __PGFE_FRONTEND_DEFAULT_GEN2(sha3_256, SHA3_256);
diff --git a/src/sha3-384.c b/src/c/hash/sha3-384.c
similarity index 95%
rename from src/sha3-384.c
rename to src/c/hash/sha3-384.c
index 2db7dea..9bb2358 100644
--- a/src/sha3-384.c
+++ b/src/c/hash/sha3-384.c
@@ -6,7 +6,8 @@
 */
 
 #include "sha3.h"
-#include "templates.c"
+
+#include "backend/templates.h"
 
 __PGFE_FRONTEND_GEN2(sha3_384);
 __PGFE_FRONTEND_DEFAULT_GEN2(sha3_384, SHA3_384);
diff --git a/src/sha3-512.c b/src/c/hash/sha3-512.c
similarity index 95%
rename from src/sha3-512.c
rename to src/c/hash/sha3-512.c
index d92aaac..77be6b3 100644
--- a/src/sha3-512.c
+++ b/src/c/hash/sha3-512.c
@@ -6,7 +6,8 @@
 */
 
 #include "sha3.h"
-#include "templates.c"
+
+#include "backend/templates.h"
 
 __PGFE_FRONTEND_GEN2(sha3_512);
 __PGFE_FRONTEND_DEFAULT_GEN2(sha3_512, SHA3_512);
diff --git a/src/sha384.c b/src/c/hash/sha384.c
similarity index 93%
rename from src/sha384.c
rename to src/c/hash/sha384.c
index 15328a3..41db829 100644
--- a/src/sha384.c
+++ b/src/c/hash/sha384.c
@@ -7,8 +7,8 @@
 
 #include "sha2.h"
 
-#include "sha2-backend.h"
-#include "templates.c"
+#include "backend/sha2-backend.h"
+#include "backend/templates.h"
 
 const pgfe_word_t __pgfe_sha384_H0[] = {
     0xC1059ED8, 0xCBBB9D5D, 0x367CD507, 0x629A292A, 0x3070DD17, 0x9159015A, 0xF70E5939, 0x152FECD8,
diff --git a/src/sha512.c b/src/c/hash/sha512.c
similarity index 97%
rename from src/sha512.c
rename to src/c/hash/sha512.c
index 9cd0b60..2e80ddf 100644
--- a/src/sha512.c
+++ b/src/c/hash/sha512.c
@@ -7,8 +7,8 @@
 
 #include "sha2.h"
 
-#include "sha2-backend.h"
-#include "templates.c"
+#include "backend/sha2-backend.h"
+#include "backend/templates.h"
 
 const pgfe_word_t __pgfe_sha512_H0[] = {
     0xF3BCC908, 0x6A09E667, 0x84CAA73B, 0xBB67AE85, 0xFE94F82B, 0x3C6EF372, 0x5F1D36F1, 0xA54FF53A,
diff --git a/src/shake.c b/src/c/hash/shake.c
similarity index 98%
rename from src/shake.c
rename to src/c/hash/shake.c
index 7e0ab8f..94147e0 100644
--- a/src/shake.c
+++ b/src/c/hash/shake.c
@@ -7,7 +7,7 @@
 
 #include "sha3.h"
 
-#include "templates.c"
+#include "backend/templates.h"
 
 // RawSHAKE128
 
diff --git a/src/hmac.c b/src/c/hmac/hmac.c
similarity index 99%
rename from src/hmac.c
rename to src/c/hmac/hmac.c
index 1e3f5af..29fe917 100644
--- a/src/hmac.c
+++ b/src/c/hmac/hmac.c
@@ -7,7 +7,7 @@
 
 #include "hmac.h"
 
-#include "generic-internal.h"
+#include "backend/generic-internal.h"
 
 #define __pgfe_hmac_tmpl(name, upper)                                                                                  \
     void pgfe_hmac_##name##_init(struct pgfe_hmac_##name##_ctx *ctx) {                                                 \
diff --git a/src/hotp.c b/src/c/otp/hotp.c
similarity index 98%
rename from src/hotp.c
rename to src/c/otp/hotp.c
index 2babd04..55cb125 100644
--- a/src/hotp.c
+++ b/src/c/otp/hotp.c
@@ -9,7 +9,7 @@
 
 #include <string.h>
 
-#include "generic-internal.h"
+#include "backend/generic-internal.h"
 #include "sha1.h"
 
 #define __PGFE_SET_SIZE_CASE_C(upper, lower)                                                                           \
diff --git a/src/otp-generic.c b/src/c/otp/otp-generic.c
similarity index 92%
rename from src/otp-generic.c
rename to src/c/otp/otp-generic.c
index c415e47..e7cc515 100644
--- a/src/otp-generic.c
+++ b/src/c/otp/otp-generic.c
@@ -5,7 +5,7 @@
   Copyright (c) 2022 Charles Dong
 */
 
-#include "otp-generic.h"
+#include "backend/otp-generic.h"
 
 pgfe_otp_t pgfe_dynamically_truncate(const pgfe_encode_t hash[], size_t length) {
     uint8_t offset = hash[length - 1] & 0xF;
diff --git a/src/totp.c b/src/c/otp/totp.c
similarity index 98%
rename from src/totp.c
rename to src/c/otp/totp.c
index 9a31f09..31450f8 100644
--- a/src/totp.c
+++ b/src/c/otp/totp.c
@@ -7,7 +7,7 @@
 
 #include "totp.h"
 
-#include "generic-internal.h"
+#include "backend/generic-internal.h"
 #include "hotp.h"
 #include "sha1.h"
 #include "utils.h"
diff --git a/src/utils.c b/src/c/utils.c
similarity index 98%
rename from src/utils.c
rename to src/c/utils.c
index 74f648e..598a863 100644
--- a/src/utils.c
+++ b/src/c/utils.c
@@ -7,7 +7,7 @@
 
 #include "utils.h"
 
-#include "generic-internal.h"
+#include "backend/generic-internal.h"
 
 size_t pgfe_hash_to_hex_string(const pgfe_encode_t hash[], size_t hash_length, char out[]) {
     char *op = out, dual_hex[3];
diff --git a/src/algorithm_selectable.cpp b/src/cpp/algorithm_selectable.cpp
similarity index 100%
rename from src/algorithm_selectable.cpp
rename to src/cpp/algorithm_selectable.cpp
diff --git a/src/abstract_base_encoding.cpp b/src/cpp/base_encoding/abstract_base_encoding.cpp
similarity index 98%
rename from src/abstract_base_encoding.cpp
rename to src/cpp/base_encoding/abstract_base_encoding.cpp
index c2f13b9..016d152 100644
--- a/src/abstract_base_encoding.cpp
+++ b/src/cpp/base_encoding/abstract_base_encoding.cpp
@@ -8,7 +8,7 @@
 #include <cmath>
 #include <cstring>
 
-#include "abstract_base_encoding.hpp"
+#include "backend_cpp/abstract_base_encoding.hpp"
 
 #define PGFE_SPACE_MULTIPLE 1.2
 
diff --git a/src/base16.cpp b/src/cpp/base_encoding/base16.cpp
similarity index 100%
rename from src/base16.cpp
rename to src/cpp/base_encoding/base16.cpp
diff --git a/src/base32.cpp b/src/cpp/base_encoding/base32.cpp
similarity index 100%
rename from src/base32.cpp
rename to src/cpp/base_encoding/base32.cpp
diff --git a/src/base64.cpp b/src/cpp/base_encoding/base64.cpp
similarity index 100%
rename from src/base64.cpp
rename to src/cpp/base_encoding/base64.cpp
diff --git a/src/generic.cpp b/src/cpp/generic.cpp
similarity index 100%
rename from src/generic.cpp
rename to src/cpp/generic.cpp
diff --git a/src/hash_encoder.cpp b/src/cpp/hash/hash_encoder.cpp
similarity index 100%
rename from src/hash_encoder.cpp
rename to src/cpp/hash/hash_encoder.cpp
diff --git a/src/hmac_encoder.cpp b/src/cpp/hmac/hmac_encoder.cpp
similarity index 100%
rename from src/hmac_encoder.cpp
rename to src/cpp/hmac/hmac_encoder.cpp
diff --git a/src/abstract_otp.cpp b/src/cpp/otp/abstract_otp.cpp
similarity index 94%
rename from src/abstract_otp.cpp
rename to src/cpp/otp/abstract_otp.cpp
index c088524..55c02ec 100644
--- a/src/abstract_otp.cpp
+++ b/src/cpp/otp/abstract_otp.cpp
@@ -5,7 +5,7 @@
   Copyright (c) 2022 Charles Dong
 */
 
-#include "abstract_otp.hpp"
+#include "backend_cpp/abstract_otp.hpp"
 
 #include <cstring>
 
diff --git a/src/hotp.cpp b/src/cpp/otp/hotp.cpp
similarity index 100%
rename from src/hotp.cpp
rename to src/cpp/otp/hotp.cpp
diff --git a/src/totp.cpp b/src/cpp/otp/totp.cpp
similarity index 100%
rename from src/totp.cpp
rename to src/cpp/otp/totp.cpp
diff --git a/src/sequential_data.cpp b/src/cpp/sequential_data.cpp
similarity index 100%
rename from src/sequential_data.cpp
rename to src/cpp/sequential_data.cpp
diff --git a/src/utils.cpp b/src/cpp/utils.cpp
similarity index 100%
rename from src/utils.cpp
rename to src/cpp/utils.cpp

From ccd390984445389ee5dd4d3629a14257825fc435 Mon Sep 17 00:00:00 2001
From: chardon55 <charlesdong_2000@outlook.com>
Date: Sun, 30 Oct 2022 12:28:10 +0800
Subject: [PATCH 12/22] Update CMakeLists.txt

---
 CMakeLists.txt | 60 +++++++++++++++++++++++++-------------------------
 1 file changed, 30 insertions(+), 30 deletions(-)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index d82f6cc..ff43c2a 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -16,38 +16,38 @@ set(include_dir "include")
 set(test_dir "test")
 
 add_library(pgfe SHARED 
-    ${src_dir}/c/generic.c 
-    ${src_dir}/c/generic-internal.c
-    ${src_dir}/c/utils.c
-    ${src_dir}/c/hash/sha-internal.c
-    ${src_dir}/c/hash/sha2-backend.c
-    ${src_dir}/c/hash/keccak-backend.c
-    ${src_dir}/c/hash/md5-backend.c
-    ${src_dir}/c/hash/sha1.c ${src_dir}/c/hash/sha224.c ${src_dir}/c/hash/sha256.c ${src_dir}/c/hash/sha384.c ${src_dir}/c/hash/sha512.c
-    ${src_dir}/c/hash/sha3-224.c ${src_dir}/c/hash/sha3-256.c ${src_dir}/c/hash/sha3-384.c ${src_dir}/c/hash/sha3-512.c 
-    ${src_dir}/c/hash/md5.c 
-    ${src_dir}/c/hash/shake.c
-    ${src_dir}/c/hmac/hmac.c
-    ${src_dir}/c/otp/otp-generic.c
-    ${src_dir}/c/otp/hotp.c ${src_dir}/c/otp/totp.c
-    ${src_dir}/c/base_encoding/base-encoding-internal.c
-    ${src_dir}/c/base_encoding/base64.c ${src_dir}/c/base_encoding/base32.c ${src_dir}/c/base_encoding/base16.c
-    ${src_dir}/cpp/generic.cpp
-    ${src_dir}/cpp/sequential_data.cpp
-    ${src_dir}/cpp/utils.cpp
-    ${src_dir}/cpp/algorithm_selectable.cpp
-    ${src_dir}/cpp/hash/hash_encoder.cpp
-    ${src_dir}/cpp/hmac/hmac_encoder.cpp
-    ${src_dir}/cpp/base_encoding/abstract_base_encoding.cpp
-    ${src_dir}/cpp/base_encoding/base16.cpp
-    ${src_dir}/cpp/base_encoding/base32.cpp
-    ${src_dir}/cpp/base_encoding/base64.cpp
-    ${src_dir}/cpp/otp/abstract_otp.cpp
-    ${src_dir}/cpp/otp/hotp.cpp ${src_dir}/cpp/otp/totp.cpp)
+  ${src_dir}/c/generic.c 
+  ${src_dir}/c/generic-internal.c
+  ${src_dir}/c/utils.c
+  ${src_dir}/c/hash/sha-internal.c
+  ${src_dir}/c/hash/sha2-backend.c
+  ${src_dir}/c/hash/keccak-backend.c
+  ${src_dir}/c/hash/md5-backend.c
+  ${src_dir}/c/hash/sha1.c ${src_dir}/c/hash/sha224.c ${src_dir}/c/hash/sha256.c ${src_dir}/c/hash/sha384.c ${src_dir}/c/hash/sha512.c
+  ${src_dir}/c/hash/sha3-224.c ${src_dir}/c/hash/sha3-256.c ${src_dir}/c/hash/sha3-384.c ${src_dir}/c/hash/sha3-512.c 
+  ${src_dir}/c/hash/md5.c 
+  ${src_dir}/c/hash/shake.c
+  ${src_dir}/c/hmac/hmac.c
+  ${src_dir}/c/otp/otp-generic.c
+  ${src_dir}/c/otp/hotp.c ${src_dir}/c/otp/totp.c
+  ${src_dir}/c/base_encoding/base-encoding-internal.c
+  ${src_dir}/c/base_encoding/base64.c ${src_dir}/c/base_encoding/base32.c ${src_dir}/c/base_encoding/base16.c
+  ${src_dir}/cpp/generic.cpp
+  ${src_dir}/cpp/sequential_data.cpp
+  ${src_dir}/cpp/utils.cpp
+  ${src_dir}/cpp/algorithm_selectable.cpp
+  ${src_dir}/cpp/hash/hash_encoder.cpp
+  ${src_dir}/cpp/hmac/hmac_encoder.cpp
+  ${src_dir}/cpp/base_encoding/abstract_base_encoding.cpp
+  ${src_dir}/cpp/base_encoding/base16.cpp
+  ${src_dir}/cpp/base_encoding/base32.cpp
+  ${src_dir}/cpp/base_encoding/base64.cpp
+  ${src_dir}/cpp/otp/abstract_otp.cpp
+  ${src_dir}/cpp/otp/hotp.cpp ${src_dir}/cpp/otp/totp.cpp)
 add_executable(pgfetest ${test_dir}/test.c)
+add_executable(pgfetestcpp ${test_dir}/test.cpp)
 # add_executable(totptest ${test_dir}/totptest.c)
 # add_executable(totptestcpp ${test_dir}/totptest.cpp)
-add_executable(pgfetestcpp ${test_dir}/test.cpp)
 
 target_include_directories(pgfe PRIVATE
   ${src_dir}
@@ -55,8 +55,8 @@ target_include_directories(pgfe PRIVATE
 )
 
 target_link_libraries(pgfetest pgfe)
-# target_link_libraries(totptest pgfe)
 target_link_libraries(pgfetestcpp pgfe)
+# target_link_libraries(totptest pgfe)
 # target_link_libraries(totptestcpp pgfe)
 
 include(${test_dir}/cmake/test_meta.cmake)

From df20d81d98a09cc3e59a409673b1bd7aabc3732c Mon Sep 17 00:00:00 2001
From: chardon55 <charlesdong_2000@outlook.com>
Date: Sun, 30 Oct 2022 12:31:47 +0800
Subject: [PATCH 13/22] Update CMakeLists.txt

---
 CMakeLists.txt | 58 ++++++++++++++++++++++++++------------------------
 1 file changed, 30 insertions(+), 28 deletions(-)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index ff43c2a..d02373d 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -12,38 +12,40 @@ include(CTest)
 enable_testing()
 
 set(src_dir "src")
+set(src_c_dir "${src_dir}/c")
+set(src_cpp_dir "${src_dir}/cpp")
 set(include_dir "include")
 set(test_dir "test")
 
 add_library(pgfe SHARED 
-  ${src_dir}/c/generic.c 
-  ${src_dir}/c/generic-internal.c
-  ${src_dir}/c/utils.c
-  ${src_dir}/c/hash/sha-internal.c
-  ${src_dir}/c/hash/sha2-backend.c
-  ${src_dir}/c/hash/keccak-backend.c
-  ${src_dir}/c/hash/md5-backend.c
-  ${src_dir}/c/hash/sha1.c ${src_dir}/c/hash/sha224.c ${src_dir}/c/hash/sha256.c ${src_dir}/c/hash/sha384.c ${src_dir}/c/hash/sha512.c
-  ${src_dir}/c/hash/sha3-224.c ${src_dir}/c/hash/sha3-256.c ${src_dir}/c/hash/sha3-384.c ${src_dir}/c/hash/sha3-512.c 
-  ${src_dir}/c/hash/md5.c 
-  ${src_dir}/c/hash/shake.c
-  ${src_dir}/c/hmac/hmac.c
-  ${src_dir}/c/otp/otp-generic.c
-  ${src_dir}/c/otp/hotp.c ${src_dir}/c/otp/totp.c
-  ${src_dir}/c/base_encoding/base-encoding-internal.c
-  ${src_dir}/c/base_encoding/base64.c ${src_dir}/c/base_encoding/base32.c ${src_dir}/c/base_encoding/base16.c
-  ${src_dir}/cpp/generic.cpp
-  ${src_dir}/cpp/sequential_data.cpp
-  ${src_dir}/cpp/utils.cpp
-  ${src_dir}/cpp/algorithm_selectable.cpp
-  ${src_dir}/cpp/hash/hash_encoder.cpp
-  ${src_dir}/cpp/hmac/hmac_encoder.cpp
-  ${src_dir}/cpp/base_encoding/abstract_base_encoding.cpp
-  ${src_dir}/cpp/base_encoding/base16.cpp
-  ${src_dir}/cpp/base_encoding/base32.cpp
-  ${src_dir}/cpp/base_encoding/base64.cpp
-  ${src_dir}/cpp/otp/abstract_otp.cpp
-  ${src_dir}/cpp/otp/hotp.cpp ${src_dir}/cpp/otp/totp.cpp)
+  ${src_c_dir}/generic.c 
+  ${src_c_dir}/generic-internal.c
+  ${src_c_dir}/utils.c
+  ${src_c_dir}/hash/sha-internal.c
+  ${src_c_dir}/hash/sha2-backend.c
+  ${src_c_dir}/hash/keccak-backend.c
+  ${src_c_dir}/hash/md5-backend.c
+  ${src_c_dir}/hash/sha1.c ${src_c_dir}/hash/sha224.c ${src_c_dir}/hash/sha256.c ${src_c_dir}/hash/sha384.c ${src_c_dir}/hash/sha512.c
+  ${src_c_dir}/hash/sha3-224.c ${src_c_dir}/hash/sha3-256.c ${src_c_dir}/hash/sha3-384.c ${src_c_dir}/hash/sha3-512.c 
+  ${src_c_dir}/hash/md5.c 
+  ${src_c_dir}/hash/shake.c
+  ${src_c_dir}/hmac/hmac.c
+  ${src_c_dir}/otp/otp-generic.c
+  ${src_c_dir}/otp/hotp.c ${src_c_dir}/otp/totp.c
+  ${src_c_dir}/base_encoding/base-encoding-internal.c
+  ${src_c_dir}/base_encoding/base64.c ${src_c_dir}/base_encoding/base32.c ${src_c_dir}/base_encoding/base16.c
+  ${src_cpp_dir}/generic.cpp
+  ${src_cpp_dir}/sequential_data.cpp
+  ${src_cpp_dir}/utils.cpp
+  ${src_cpp_dir}/algorithm_selectable.cpp
+  ${src_cpp_dir}/hash/hash_encoder.cpp
+  ${src_cpp_dir}/hmac/hmac_encoder.cpp
+  ${src_cpp_dir}/base_encoding/abstract_base_encoding.cpp
+  ${src_cpp_dir}/base_encoding/base16.cpp
+  ${src_cpp_dir}/base_encoding/base32.cpp
+  ${src_cpp_dir}/base_encoding/base64.cpp
+  ${src_cpp_dir}/otp/abstract_otp.cpp
+  ${src_cpp_dir}/otp/hotp.cpp ${src_cpp_dir}/otp/totp.cpp)
 add_executable(pgfetest ${test_dir}/test.c)
 add_executable(pgfetestcpp ${test_dir}/test.cpp)
 # add_executable(totptest ${test_dir}/totptest.c)

From 2edc341f1cd8def9d8dc9eebe2958dbfae2048d5 Mon Sep 17 00:00:00 2001
From: chardon55 <charlesdong_2000@outlook.com>
Date: Sun, 30 Oct 2022 12:38:01 +0800
Subject: [PATCH 14/22] Update README.md

---
 README.md | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/README.md b/README.md
index 964c324..e9aff11 100644
--- a/README.md
+++ b/README.md
@@ -11,7 +11,9 @@
 
 *libpgfe* currently supports hash encoding (e.g. SHA256, MD5), HMAC encoding, HOTP/TOTP and Base 16/32/64.
 
-| Item         | Content             |
+*libpgfe* is currently under heavy development, more features and optimization will be added in the future.
+
+| Entry        | Info                |
 | :----------- | :------------------ |
 | C Standard   | [C11 (ISO/IEC 9899:2011)](https://en.wikipedia.org/wiki/C11_(C_standard_revision))  |
 | C++ Standard | [C++14 (ISO/IEC 14882:2014)](https://en.wikipedia.org/wiki/C++14) |

From 2e3e2f57813821be0a821ef71402f83498f4bcb7 Mon Sep 17 00:00:00 2001
From: chardon55 <charlesdong_2000@outlook.com>
Date: Sun, 30 Oct 2022 13:12:42 +0800
Subject: [PATCH 15/22] Update info

---
 .github/qna.md | 14 +++++++++++---
 README.md      |  4 +---
 2 files changed, 12 insertions(+), 6 deletions(-)

diff --git a/.github/qna.md b/.github/qna.md
index dab3a96..5584076 100644
--- a/.github/qna.md
+++ b/.github/qna.md
@@ -11,13 +11,21 @@ Since v0.2.0, *libpgfe* has been "self-sufficient" and does not depend on any th
 I will think about it eventually, but not now! Because byte order compatibility will dramatically increase complexity of the code,
 and I currently don't have enough time or effort to tackle it. Also, I do not have Big Endian machines or virtual machines, so the additional code would be left untested, which is what I don't want to happen.
 
-## Q3: Why not MSVC?
+## Q3: Why not [Assembly Language](https://en.wikipedia.org/wiki/Assembly_language)?
+
+1. I'm not familiar with Assembly.
+
+2. Assembly is machine-dependent.
+
+3. C is fast enough for *libpgfe*. It's no need to use Assembly to do those optimizations.
+
+## Q4: Why not MSVC?
 
 > ***PS:** MSVC = Microsoft Visual C++*
 
-Firstly, this library prioritizes POSIX compatibility, instead of Windows compatibility.
+1. This library prioritizes POSIX compatibility, instead of Windows compatibility.
 
-Secondly, *libpgfe* needs some necessary features that are not included in *MSVC*. For instance, like the C code below:
+2. *libpgfe* needs some necessary features that are not included in *MSVC*. For instance, like the C code below:
 
 ```c
 int main() {
diff --git a/README.md b/README.md
index e9aff11..8cc6d5c 100644
--- a/README.md
+++ b/README.md
@@ -22,9 +22,7 @@
 
 [*Any questions?*](.github/qna.md)
 
-## Endianness (Byte order)
-
-> [*What is it anyway??*](https://en.wikipedia.org/wiki/Endianness)
+## [Endianness (Byte order)](https://en.wikipedia.org/wiki/Endianness)
 
 The implementation philosophy of *libpgfe* assumes that the systems running this library are **Little Endian**, since it is widely used by architectures and OS. Therefore, this library should not run properly on Big Endian systems.
 

From 877e1d05442e818863437c9bfae35ecd953e6d41 Mon Sep 17 00:00:00 2001
From: chardon55 <charlesdong_2000@outlook.com>
Date: Sun, 30 Oct 2022 13:14:35 +0800
Subject: [PATCH 16/22] Update qna.md

---
 .github/qna.md | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/.github/qna.md b/.github/qna.md
index 5584076..6a062f0 100644
--- a/.github/qna.md
+++ b/.github/qna.md
@@ -25,7 +25,7 @@ and I currently don't have enough time or effort to tackle it. Also, I do not ha
 
 1. This library prioritizes POSIX compatibility, instead of Windows compatibility.
 
-2. *libpgfe* needs some necessary features that are not included in *MSVC*. For instance, like the C code below:
+2. *libpgfe* needs some necessary features that are not included in *MSVC*. For instance, like the C code below. *MSVC* will refuse to compile that code, because a variable is used as the array's size, while *Clang* and *GCC* are OK with it.
 
 ```c
 int main() {
@@ -35,5 +35,3 @@ int main() {
     return 0;
 }
 ```
-
-*MSVC* will refuse to compile that code, because a variable is used as the array's size, while *Clang* and *GCC* are OK with it.

From 5d1dd2e3c01c2fead6e51e11fe7e62b8bb0e5f0b Mon Sep 17 00:00:00 2001
From: chardon55 <charlesdong_2000@outlook.com>
Date: Sun, 30 Oct 2022 13:16:53 +0800
Subject: [PATCH 17/22] Update qna.md

---
 .github/qna.md | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/.github/qna.md b/.github/qna.md
index 6a062f0..89c4435 100644
--- a/.github/qna.md
+++ b/.github/qna.md
@@ -9,7 +9,7 @@ Since v0.2.0, *libpgfe* has been "self-sufficient" and does not depend on any th
 ## Q2: Interested in supporting Big Endian?
 
 I will think about it eventually, but not now! Because byte order compatibility will dramatically increase complexity of the code,
-and I currently don't have enough time or effort to tackle it. Also, I do not have Big Endian machines or virtual machines, so the additional code would be left untested, which is what I don't want to happen.
+and I currently don't have enough time or effort to tackle it. Also, I do not have Big Endian machines or virtual machines, so the additional code would be left untested, which is what I don't expect.
 
 ## Q3: Why not [Assembly Language](https://en.wikipedia.org/wiki/Assembly_language)?
 

From a3f2f465e2568d7b5ca60285f3b22ccdeecdf470 Mon Sep 17 00:00:00 2001
From: chardon55 <charlesdong_2000@outlook.com>
Date: Sun, 30 Oct 2022 13:17:53 +0800
Subject: [PATCH 18/22] Update info content

---
 .github/qna.md | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/.github/qna.md b/.github/qna.md
index 89c4435..cec4f98 100644
--- a/.github/qna.md
+++ b/.github/qna.md
@@ -9,7 +9,7 @@ Since v0.2.0, *libpgfe* has been "self-sufficient" and does not depend on any th
 ## Q2: Interested in supporting Big Endian?
 
 I will think about it eventually, but not now! Because byte order compatibility will dramatically increase complexity of the code,
-and I currently don't have enough time or effort to tackle it. Also, I do not have Big Endian machines or virtual machines, so the additional code would be left untested, which is what I don't expect.
+and I currently don't have enough time or effort to tackle it. Also, I do not have Big Endian machines or virtual machines, so the additional code would be left untested, which is not what I expect.
 
 ## Q3: Why not [Assembly Language](https://en.wikipedia.org/wiki/Assembly_language)?
 

From 3372e374d785466f15a9dd6643b1c37e2caa560d Mon Sep 17 00:00:00 2001
From: chardon55 <charlesdong_2000@outlook.com>
Date: Sun, 30 Oct 2022 14:07:32 +0800
Subject: [PATCH 19/22] Add comment header

---
 src/cpp/algorithm_selectable.cpp | 7 +++++++
 src/cpp/generic.cpp              | 7 +++++++
 2 files changed, 14 insertions(+)

diff --git a/src/cpp/algorithm_selectable.cpp b/src/cpp/algorithm_selectable.cpp
index 7f6e1b9..2993c0f 100644
--- a/src/cpp/algorithm_selectable.cpp
+++ b/src/cpp/algorithm_selectable.cpp
@@ -1,3 +1,10 @@
+/*
+  libpgfe
+  algorithm_selectable.cpp
+
+  Copyright (c) 2022 Charles Dong
+*/
+
 #include "algorithm_selectable.hpp"
 
 using namespace chardon55::PGFE;
diff --git a/src/cpp/generic.cpp b/src/cpp/generic.cpp
index 97821d6..5df02ba 100644
--- a/src/cpp/generic.cpp
+++ b/src/cpp/generic.cpp
@@ -1,3 +1,10 @@
+/*
+  libpgfe
+  generic.cpp
+
+  Copyright (c) 2022 Charles Dong
+*/
+
 #ifndef LIBPGFE_GENERIC_CPP
 #define LIBPGFE_GENERIC_CPP
 

From ff85b51f390fda4e35c91d41ed9a778c5a677418 Mon Sep 17 00:00:00 2001
From: chardon55 <charlesdong_2000@outlook.com>
Date: Sun, 30 Oct 2022 14:07:40 +0800
Subject: [PATCH 20/22] Update metadata

---
 Makefile                                      |  2 +-
 include/{meta.h => version.h}                 | 10 ++---
 meta.mak => metadata.mak                      |  0
 project.json                                  |  4 ++
 scripts/{comment_header.py => comment_header} | 13 +++---
 scripts/{deploy.py => deploy}                 | 26 ++++++-----
 scripts/metadata.mak.in                       | 15 +++++++
 scripts/update_meta                           | 37 ++++++++++++++++
 scripts/update_meta.py                        | 43 -------------------
 scripts/version.h.template                    | 11 +++++
 10 files changed, 97 insertions(+), 64 deletions(-)
 rename include/{meta.h => version.h} (67%)
 rename meta.mak => metadata.mak (100%)
 create mode 100644 project.json
 rename scripts/{comment_header.py => comment_header} (77%)
 mode change 100644 => 100755
 rename scripts/{deploy.py => deploy} (79%)
 mode change 100644 => 100755
 create mode 100644 scripts/metadata.mak.in
 create mode 100755 scripts/update_meta
 delete mode 100644 scripts/update_meta.py
 create mode 100644 scripts/version.h.template

diff --git a/Makefile b/Makefile
index b9d3b3b..d93e37b 100644
--- a/Makefile
+++ b/Makefile
@@ -1,4 +1,4 @@
-include meta.mak
+include metadata.mak
 
 .PHONY: all rebuild clean test install uninstall
 
diff --git a/include/meta.h b/include/version.h
similarity index 67%
rename from include/meta.h
rename to include/version.h
index e5aa612..dbbbc2d 100644
--- a/include/meta.h
+++ b/include/version.h
@@ -1,18 +1,18 @@
 /*
   libpgfe
-  meta.h
+  version.h
 
   Copyright (c) 2022 Charles Dong
 */
 
-#ifndef LIBPGFE_META_H
-#define LIBPGFE_META_H
-
-#define LIBPGFE_NAME "libpgfe"
+#ifndef LIBPGFE_VERSION_H
+#define LIBPGFE_VERSION_H
 
 #define LIBPGFE_MAJOR_VERSION 0
 #define LIBPGFE_MINOR_VERSION 5
 #define LIBPGFE_REVISION 0
+#define LIBPGFE_VARIANT 
 
 #define LIBPGFE_VERSION "0.5.0"
+
 #endif
diff --git a/meta.mak b/metadata.mak
similarity index 100%
rename from meta.mak
rename to metadata.mak
diff --git a/project.json b/project.json
new file mode 100644
index 0000000..fca74ae
--- /dev/null
+++ b/project.json
@@ -0,0 +1,4 @@
+{
+    "name": "libpgfe",
+    "version": "0.5.0"
+}
\ No newline at end of file
diff --git a/scripts/comment_header.py b/scripts/comment_header
old mode 100644
new mode 100755
similarity index 77%
rename from scripts/comment_header.py
rename to scripts/comment_header
index 19e658d..c0340d4
--- a/scripts/comment_header.py
+++ b/scripts/comment_header
@@ -1,3 +1,5 @@
+#!/usr/bin/env python3
+
 from pathlib import Path
 import sys
 
@@ -24,7 +26,7 @@ def add_comment_header(file: Path):
     print(f"Updated {file}")
 
 
-def iter_dir(path_item: Path):
+def iter_dir(path_item: Path, inside_subdir=False):
     if not path_item.exists():
         return
 
@@ -32,10 +34,10 @@ def iter_dir(path_item: Path):
         add_comment_header(path_item)
     else:
         for item in path_item.iterdir():
-            if item.is_dir() and item.name in INCLUDE_SUBDIR:
-                iter_dir(item)
+            if item.is_dir() and (item.name in INCLUDE_SUBDIR or inside_subdir):
+                iter_dir(item, inside_subdir=True)
                 continue
-            
+
             if item.name.split('.')[-1] in EXTS:
                 add_comment_header(item)
 
@@ -44,5 +46,6 @@ def main(args):
     if len(args) > 0:
         iter_dir(Path(args[0]))
 
+
 if __name__ == "__main__":
-    main(sys.argv[1:])
\ No newline at end of file
+    main(sys.argv[1:])
diff --git a/scripts/deploy.py b/scripts/deploy
old mode 100644
new mode 100755
similarity index 79%
rename from scripts/deploy.py
rename to scripts/deploy
index 0dba1ac..60f1097
--- a/scripts/deploy.py
+++ b/scripts/deploy
@@ -1,3 +1,5 @@
+#!/usr/bin/env python3
+
 from argparse import ArgumentParser
 import os
 from glob import glob
@@ -8,20 +10,21 @@
 SHARED_LIB = "libpgfe.so"
 LIB_DIR = "./build"
 
+
 def main(args):
     if args.uninstall:
         for ds in args.header_dir:
             _dir = Path(ds) / HEADER_ROOT
             if not _dir.exists():
                 continue
-            
+
             shutil.rmtree(_dir)
-        
+
         for ss in args.lib_dir:
             _dir = Path(ss)
             if not _dir.exists():
                 continue
-            
+
             os.remove(_dir / SHARED_LIB)
 
     else:
@@ -29,23 +32,26 @@ def main(args):
             _dir = Path(ds) / HEADER_ROOT
             if not _dir.exists():
                 _dir.mkdir(parents=True)
-            
+
             for f in glob(r'./*.h'):
                 shutil.copy(f, _dir)
-            
+
             for f in glob(r'./*.hpp'):
                 shutil.copy(f, _dir)
-        
+
         for ss in args.lib_dir:
             _dir = Path(ss)
             if not _dir.exists():
                 _dir.mkdir(parents=True)
-            
+
             shutil.copy(str(Path(LIB_DIR, SHARED_LIB)), _dir)
 
+
 if __name__ == '__main__':
     ap = ArgumentParser()
-    ap.add_argument("-h", "--header-dir", required=True, nargs='*', action='extend', default=[])
-    ap.add_argument("-l", "--lib-dir", required=True, nargs='*', action='extend', default=[])
+    ap.add_argument("-h", "--header-dir", required=True,
+                    nargs='*', action='extend', default=[])
+    ap.add_argument("-l", "--lib-dir", required=True,
+                    nargs='*', action='extend', default=[])
     ap.add_argument("-u", "--uninstall", action='store_true')
-    main(ap.parse_args())
\ No newline at end of file
+    main(ap.parse_args())
diff --git a/scripts/metadata.mak.in b/scripts/metadata.mak.in
new file mode 100644
index 0000000..8a9c71c
--- /dev/null
+++ b/scripts/metadata.mak.in
@@ -0,0 +1,15 @@
+PROJECT := {name}
+VERSION := {version}
+
+BUILD_DIR := build
+
+INCLUDE_DIR := include
+SRC_DIR := src
+
+HEADER_DIR := /usr/local/include/libpgfe
+LIB_DIR := /usr/lib
+TARGET_DIR := $(BUILD_DIR)
+TARGET_FILE := $(PROJECT).so
+
+TARGET := $(TARGET_DIR)/$(TARGET_FILE)
+TEST_TARGET := $(TARGET_DIR)/$(TEST_BIN)
\ No newline at end of file
diff --git a/scripts/update_meta b/scripts/update_meta
new file mode 100755
index 0000000..48c92d1
--- /dev/null
+++ b/scripts/update_meta
@@ -0,0 +1,37 @@
+#!/usr/bin/env python3
+
+import json
+
+
+FILES = {
+    "scripts/metadata.mak.in": "metadata.mak",
+    "scripts/version.h.template": "include/version.h",
+}
+
+
+def main():
+    p = {}
+    with open("project.json") as fp:
+        p = json.load(fp)
+
+    name = p['name']
+    version = p['version']
+    version_list = [int(i) for i in version.split('-')[0].split('.')]
+
+    info = {
+        "name": name,
+        "version": version,
+        "major_version": version_list[0],
+        "minor_version": version_list[1],
+        "revision": version_list[2],
+        "variant": '-'.join(version.split('-')[1:]),
+    }
+
+    for src, dest in FILES.items():
+        with open(src, 'r') as s_fp:
+            with open(dest, 'w') as d_fp:
+                d_fp.write(s_fp.read().format(**info))
+
+
+if __name__ == '__main__':
+    main()
diff --git a/scripts/update_meta.py b/scripts/update_meta.py
deleted file mode 100644
index 68fff5f..0000000
--- a/scripts/update_meta.py
+++ /dev/null
@@ -1,43 +0,0 @@
-import sys
-
-import json
-
-
-def main(args):
-    p = {}
-    with open(args[0]) as fp:
-        p = json.load(fp)
-
-    name = p['name']
-    version = p['version']
-    version_list = [int(i) for i in version.split('.')]
-
-    with open('meta.mak', 'w') as f:
-        f.write(f'''\
-PROJECT := {name}
-VERSION := {version}
-
-BUILD_DIR := build
-TARGET_DIR := $(BUILD_DIR)/bin
-''')
-
-    nameuc = name.upper()
-
-    with open('meta.h', 'w') as f:
-        f.write(f'''\
-#ifndef {nameuc}_META_H
-#define {nameuc}_META_H
-
-#define {nameuc}_NAME "{name}"
-
-#define {nameuc}_MAJOR_VERSION {version_list[0]}
-#define {nameuc}_MINOR_VERSION {version_list[1]}
-#define {nameuc}_REVISION {version_list[2]}
-
-#define {nameuc}_VERSION "{version}"
-#endif
-        ''')
-
-
-if __name__ == '__main__':
-    main(sys.argv[1:])
diff --git a/scripts/version.h.template b/scripts/version.h.template
new file mode 100644
index 0000000..f921ca9
--- /dev/null
+++ b/scripts/version.h.template
@@ -0,0 +1,11 @@
+#ifndef LIBPGFE_VERSION_H
+#define LIBPGFE_VERSION_H
+
+#define LIBPGFE_MAJOR_VERSION {major_version}
+#define LIBPGFE_MINOR_VERSION {minor_version}
+#define LIBPGFE_REVISION {revision}
+#define LIBPGFE_VARIANT {variant}
+
+#define LIBPGFE_VERSION "{version}"
+
+#endif

From 1e76e4e2bcc302d5344f04f8e2df04a6aa9d5ca1 Mon Sep 17 00:00:00 2001
From: chardon55 <charlesdong_2000@outlook.com>
Date: Sun, 30 Oct 2022 14:09:34 +0800
Subject: [PATCH 21/22] Bug fix

---
 include/version.h          | 2 +-
 scripts/version.h.template | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/include/version.h b/include/version.h
index dbbbc2d..1d99022 100644
--- a/include/version.h
+++ b/include/version.h
@@ -11,7 +11,7 @@
 #define LIBPGFE_MAJOR_VERSION 0
 #define LIBPGFE_MINOR_VERSION 5
 #define LIBPGFE_REVISION 0
-#define LIBPGFE_VARIANT 
+#define LIBPGFE_VARIANT ""
 
 #define LIBPGFE_VERSION "0.5.0"
 
diff --git a/scripts/version.h.template b/scripts/version.h.template
index f921ca9..f53ec14 100644
--- a/scripts/version.h.template
+++ b/scripts/version.h.template
@@ -4,7 +4,7 @@
 #define LIBPGFE_MAJOR_VERSION {major_version}
 #define LIBPGFE_MINOR_VERSION {minor_version}
 #define LIBPGFE_REVISION {revision}
-#define LIBPGFE_VARIANT {variant}
+#define LIBPGFE_VARIANT "{variant}"
 
 #define LIBPGFE_VERSION "{version}"
 

From 83aa7192c8b4490267e3eb177ca922d255dfa284 Mon Sep 17 00:00:00 2001
From: chardon55 <charlesdong_2000@outlook.com>
Date: Sun, 30 Oct 2022 14:13:33 +0800
Subject: [PATCH 22/22] Update Makefile

---
 Makefile | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/Makefile b/Makefile
index d93e37b..1d493f7 100644
--- a/Makefile
+++ b/Makefile
@@ -1,6 +1,6 @@
 include metadata.mak
 
-.PHONY: all rebuild clean test install uninstall
+.PHONY: all rebuild clean test install uninstall init-scripts
 
 all: 
 	@echo 'Building...'
@@ -37,3 +37,6 @@ uninstall:
 	@echo 'Removing shared library...'
 	@rm -vrf $(LIB_DIR)/$(TARGET_FILE)
 	@echo done
+
+init-scripts:
+	@chmod u+x ./scripts/{comment_header,update_meta,deploy}