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LibNMS

This project provides a dynamically linked library that contains the necessary functionality to recreate the famous data decryption effect shown in the 1992 film Sneakers.

It's intended purpose is to be used for any software project whose author may wish to use this effect when presenting data to the user. This library also provides capabilities for getting user input in the case of a menu or set of selections is presented to the user. See the usage section for details.

This library has no dependencies, but it does rely on ANSI/VT100 escape sequences to recreate the effect. Most modern terminal programs support these sequences so this should not be an issue for most users. If yours does not, you may need to use an alternate terminal program like xTerm.

If you wish to get an idea of how this looks or if it will work on your system, without needing to implement this library inside a separate program, you can download and install my other project, no-more-secrets, which implements this same code in a command line tool that applies the effect to piped data.

Screen Cap:

Table of Contents

1. Download and Install
2. Compiling
3. Usage
4. License

Download and Install

In order to download and build this library, you will need to have git, gcc, and make installed. Install them from your package manager if not already installed.

$ which make
/usr/bin/make

$ which gcc
/usr/bin/gcc

$ which git
/usr/bin/git

Download and Install:

$ git clone https://github.com/bartobri/libnms.git
$ cd libnms
$ make
$ sudo make install

Uninstall:

$ sudo make uninstall

Compiling

You must tell the compiler to include the nms library.

gcc myprogram.c -lnms

Usage

Synopsys

include <nms.h>

int main(void) {

    // Apply the effect to the string "setec astronomy"
    nms_exec("setec astronomy");
    
    // Make the foreground color of the decrypted characters "red"
    nms_set_foreground_color("red");
    nms_exec("setec astronomy");
    
    // Initiate decryption sequence without requiring a key press
    nms_set_auto_decrypt(1);
    nms_exec("setec astronomy");
    
    // Clear screen prior to displaying any output
    nms_set_clear_scr(1);
    nms_exec("setec astronomy");
    
    // Do not use color (for terminals that don't support color)
    nms_use_color(0);
    nms_exec("setec astronomy");
    
    // Require the user to choose 1, 2, or 3 before returning execution to main()
    nms_set_return_opts("123");
    char c = nms_exec("Choose: [1] apples [2] oranges [3] pears");
    printf("User chose %c", c);
    
    // Set the cursor position to 0/2 (x/y) when getting user selection
    nms_set_input_position(0, 2);
    nms_set_return_opts("123");
    char c = nms_exec("Choose: [1] apples [2] oranges [3] pears");
    printf("User chose %c", c);
    
    return 0;
}

Functions

char nms_exec(char *)

The nms_exec() is the primary function for this library. It applies the movie effect to a given string of characters. If nms_set_return_opts() is used, this function will return the user selection. Otherwise it returns zero.

This is the only function that must be called to generate the movie effect. All other functions are used to taylor its behavior. Read below for more.

void nms_set_foreground_color(char *)

The nms_set_foreground_color() function sets the desired foreground color of the decrypted characters displayed by nms_exec(). Valid arguments are "white", "yellow", "black", "magenta", "blue", "green", "red" and "cyan". Blue is the default. No value is returned.

void nms_set_auto_decrypt(int)

The nms_set_auto_decrypt() function sets a flag that nms_exec() uses to initiate the decryption sequence without the need for the user to press a key. If the integer argument is evaluated as true, the flag is turned on. If false, it is turned off.

void nms_set_clear_scr(int)

The nms_set_clear_scr() function sets a flag that nms_exec() checks to determine if it will clear the screen prior to displaying any output. If the integer argument is evaluated as true, the flag is turned on. If false, it is turned off. The flag is off by default. Note that the screen contents prior to clearing are saved and restored once the effect has completed.

void nms_use_color(int)

The nms_use_color() function sets a flag that nms_exec() checks to determine if it will use color escape sequences when displaying unencrypted characters. If the integer argument is evaluated as true, the flag is turned on. If false, it is turned off. The flag is on by default. This function exists to support terminals that do not have color capabilities.

void nms_set_return_opts(char *)

The nms_set_return_opts() function sets the character options that nms_exec() requires the user to choose from before it returns execution to the calling function. This is intended to be used for cases where the string passed to nms_exec() contains a menu with a set of selections. Note that nms_exec() returns the selection to the calling function.

void nms_set_input_position(int, int)

The nms_set_input_position() function is meant to be used in conjunction with the nms_set_return_opts() function. It sets the cursor position to the given x/y coordinates when nms_exec() requires a menu selection from the user.

License

This program is free software; you can redistribute it and/or modify it under the terms of the the MIT License (MIT). See LICENSE for more details.