From 7f5a8c2cc2a93e6dbf463e8b47104b88e8c2ee5e Mon Sep 17 00:00:00 2001
From: Alexis Jeandet <alexis.jeandet@member.fsf.org>
Date: Thu, 11 Jan 2024 14:07:16 +0100
Subject: [PATCH] Basic WASM POC showing CDF variables count

Signed-off-by: Alexis Jeandet <alexis.jeandet@member.fsf.org>
---
 .../cdfpp/cdf-io/loading/records-loading.hpp  | 11 +--
 meson.build                                   |  5 +-
 wacdfpp/meson.build                           | 22 ++++++
 wacdfpp/wacdfpp.cpp                           | 72 +++++++++++++++++++
 wacdfpp/wacdfpp.html                          | 48 +++++++++++++
 wacdfpp/wasm.txt                              | 23 ++++++
 6 files changed, 175 insertions(+), 6 deletions(-)
 create mode 100644 wacdfpp/meson.build
 create mode 100644 wacdfpp/wacdfpp.cpp
 create mode 100644 wacdfpp/wacdfpp.html
 create mode 100644 wacdfpp/wasm.txt

diff --git a/include/cdfpp/cdf-io/loading/records-loading.hpp b/include/cdfpp/cdf-io/loading/records-loading.hpp
index dab0d9c..883e02e 100644
--- a/include/cdfpp/cdf-io/loading/records-loading.hpp
+++ b/include/cdfpp/cdf-io/loading/records-loading.hpp
@@ -56,7 +56,7 @@ struct parsing_context_t
     }
 };
 
-SPLIT_FIELDS_FW_DECL(std::size_t, load_record,);
+SPLIT_FIELDS_FW_DECL(std::size_t, load_record, );
 
 template <typename record_t, typename parsing_context_t, typename T>
 inline std::size_t load_field(
@@ -135,7 +135,7 @@ inline std::size_t load_fields(const record_t& r, parsing_context_t& parsing_con
     return load_fields(r, parsing_context, offset, std::forward<Ts>(fields)...);
 }
 
-SPLIT_FIELDS(std::size_t, load_record, load_fields,);
+SPLIT_FIELDS(std::size_t, load_record, load_fields, );
 
 
 template <typename version_t>
@@ -289,7 +289,7 @@ auto begin_AgrEDR(const cdf_ADR_t<version_t>& adr, buffer_t& buffer)
 {
     using aedr_t = cdf_AgrEDR_t<version_t>;
 
-    return blk_iterator<aedr_t, buffer_t> { adr.AgrEDRhead, buffer,
+    return blk_iterator<aedr_t, buffer_t> { static_cast<std::size_t>(adr.AgrEDRhead), buffer,
         [](const aedr_t& aedr) { return aedr.AEDRnext; } };
 }
 
@@ -305,7 +305,7 @@ auto begin_AzEDR(const cdf_ADR_t<version_t>& adr, buffer_t& buffer)
 {
     using aedr_t = cdf_AzEDR_t<version_t>;
 
-    return blk_iterator<aedr_t, buffer_t> { adr.AzEDRhead, buffer,
+    return blk_iterator<aedr_t, buffer_t> { static_cast<std::size_t>(adr.AzEDRhead), buffer,
         [](const aedr_t& aedr) { return aedr.AEDRnext; } };
 }
 
@@ -351,7 +351,8 @@ auto begin_VDR(parsing_context_t& parsing_context)
     else if constexpr (type == cdf_r_z::z)
     {
         using vdr_t = cdf_zVDR_t<version_t>;
-        return blk_iterator<vdr_t, parsing_context_t> { parsing_context.gdr.zVDRhead,
+        return blk_iterator<vdr_t, parsing_context_t> { static_cast<std::size_t>(
+                                                            parsing_context.gdr.zVDRhead),
             parsing_context, [](const vdr_t& vdr) { return vdr.VDRnext; } };
     }
 }
diff --git a/meson.build b/meson.build
index 6f11b55..aaf4f8b 100644
--- a/meson.build
+++ b/meson.build
@@ -1,7 +1,7 @@
 project(
   'pycdfpp',
   'cpp','c',
-  meson_version: '>= 0.63.0',
+  meson_version: '>= 0.64.0',
   version : run_command('scripts/version.py',
                         capture:true,
                         env:{'SRC_ROOT':meson.project_source_root()}
@@ -226,6 +226,9 @@ install_headers(
 ], subdir:'cdfpp/cdf-io/saving')
 
 
+subdir('wacdfpp')
+
+
 if get_option('with_tests')
 
     configure_file(output : 'tests_config.hpp',
diff --git a/wacdfpp/meson.build b/wacdfpp/meson.build
new file mode 100644
index 0000000..b09c3f3
--- /dev/null
+++ b/wacdfpp/meson.build
@@ -0,0 +1,22 @@
+fs = import('fs')
+
+
+flags = ['-sWASM=2', '-sALLOW_MEMORY_GROWTH', '-sFETCH=1', '-sASYNCIFY']+['-sWASM=2', '-sEXPORT_ALL=1', '-sMODULARIZE', '-sEXPORTED_RUNTIME_METHODS=ccall', '-lembind', '-sFETCH=1', '--bind', '-sALLOW_MEMORY_GROWTH']
+
+lib_wacdfpp = library('wacdfpp', 'wacdfpp.cpp',
+                    dependencies:[cdfpp_dep],
+                    cpp_args : flags,
+                    install: false,
+                    link_args : flags,
+                    build_by_default: meson.get_compiler('cpp').get_id() == 'emscripten',
+                    extra_files : ['wasm.txt', 'wacdfpp.html']
+                    )
+
+js_wrapper = custom_target('js_wrapper',
+    input : lib_wacdfpp,
+    output : 'wacdfpp.js',
+    command : [ 'emcc', '-lembind', '-sFETCH=1', '-sWASM=2',  '--bind', '-sALLOW_MEMORY_GROWTH',  '-sASYNCIFY', '-o', '@OUTPUT@', '-Wl,--whole-archive','@INPUT@', '-Wl,--no-whole-archive'],
+    build_by_default: true
+)
+
+fs.copyfile('wacdfpp.html', 'wacdfpp.html')
diff --git a/wacdfpp/wacdfpp.cpp b/wacdfpp/wacdfpp.cpp
new file mode 100644
index 0000000..e5bbd26
--- /dev/null
+++ b/wacdfpp/wacdfpp.cpp
@@ -0,0 +1,72 @@
+#include <cdfpp/cdf.hpp>
+#include <filesystem>
+#include <iostream>
+#include <string>
+#include <vector>
+#if __has_include(<emscripten.h>)
+#include <emscripten.h>
+#include <emscripten/bind.h>
+#include <emscripten/fetch.h>
+#else
+#define EMSCRIPTEN_KEEPALIVE
+#define EMSCRIPTEN_EXPORT(x) x
+#endif
+
+
+EMSCRIPTEN_KEEPALIVE
+emscripten::val count_variables(std::string url)
+{
+    struct fetch_data
+    {
+        bool done = false;
+        std::vector<char> data;
+    };
+    emscripten_fetch_attr_t attr;
+    emscripten_fetch_attr_init(&attr);
+    strcpy(attr.requestMethod, "GET");
+    attr.attributes = EMSCRIPTEN_FETCH_LOAD_TO_MEMORY;
+    attr.userData = new fetch_data;
+    attr.onsuccess = [](emscripten_fetch_t* fetch)
+    {
+        auto data = static_cast<fetch_data*>(fetch->userData);
+        data->data = std::vector<char>(fetch->data, fetch->data + fetch->numBytes);
+        data->done = true;
+        emscripten_fetch_close(fetch);
+    };
+    attr.onerror = [](emscripten_fetch_t* fetch)
+    {
+        auto data = static_cast<fetch_data*>(fetch->userData);
+        data->done = true;
+        emscripten_fetch_close(fetch);
+    };
+    emscripten_fetch(&attr, url.c_str());
+    while (!static_cast<fetch_data*>(attr.userData)->done)
+    {
+        emscripten_sleep(10);
+    }
+    auto data = static_cast<fetch_data*>(attr.userData);
+    if (auto cdf_file = cdf::io::load(data->data); cdf_file)
+    {
+        std::cout << "Variables: " << std::size(cdf_file->variables) << "\n";
+        auto sz = std::size(cdf_file->variables);
+        delete data;
+        return emscripten::val(sz);
+    }
+    return emscripten::val(-1);
+}
+
+
+EMSCRIPTEN_KEEPALIVE
+int my_cdf_test()
+{
+    return 42;
+}
+
+
+#ifdef __EMSCRIPTEN__
+EMSCRIPTEN_BINDINGS(cdfppjs)
+{
+    emscripten::function("my_cdf_test", &my_cdf_test);
+    emscripten::function("count_variables", &count_variables);
+}
+#endif
diff --git a/wacdfpp/wacdfpp.html b/wacdfpp/wacdfpp.html
new file mode 100644
index 0000000..d0fc824
--- /dev/null
+++ b/wacdfpp/wacdfpp.html
@@ -0,0 +1,48 @@
+<!doctype html>
+<html>
+<body>
+<canvas id="canvas" width="400" height="400"></canvas>
+<div id="container">
+  <p>
+    <input type="text" id="URL" name="URL" />
+    <input id="myButton" type=button value="Read CDF">
+    <output name="result" id="count"/>
+  </p>
+</div>
+<script>
+
+  console.log("loading wasm");
+
+  var Module = {
+    canvas: (function() {
+      var canvas = document.getElementById('canvas');
+      return canvas;
+    })(),
+
+    onRuntimeInitialized: function() {
+      console.log("wasm loaded");
+      console.log("wasm initialized");
+    }
+  };
+</script>
+<script src="wacdfpp.js"></script>
+
+<script>
+  function callback() {
+    const URL = document.getElementById("URL").value;
+
+    // Disable the button while the operation is in progress
+    document.getElementById("myButton").disabled = true;
+
+    // Fetch the data and process it asynchronously
+    Module.count_variables(URL).then(function(count) {
+      // Update the count and enable the button when processing is done
+      document.getElementById("count").innerHTML = count;
+      document.getElementById("myButton").disabled = false;
+    });
+  }
+
+  myButton.addEventListener('click', callback);
+</script>
+</body>
+</html>
diff --git a/wacdfpp/wasm.txt b/wacdfpp/wasm.txt
new file mode 100644
index 0000000..a12263d
--- /dev/null
+++ b/wacdfpp/wasm.txt
@@ -0,0 +1,23 @@
+[binaries]
+c = 'emcc'
+cpp = 'em++'
+ar = 'emar'
+exe_wrapper = 'node'
+
+[built-in options]
+c_args = []
+c_link_args = ['-sEXPORT_ALL=1', '-sWASM=2', '-sMODULARIZE', '-sEXPORTED_RUNTIME_METHODS=ccall']
+cpp_args = []
+cpp_link_args = []
+
+
+[properties]
+# Emscripten always needs an exe wrapper. Again,
+# maybe Meson could just know this.
+needs_exe_wrapper = true
+
+[host_machine]
+system = 'wasm'
+cpu_family = 'wasm'
+cpu = 'wasm'
+endian = 'little'