TextMode

Used in conjuction with SDL 2, TextMode is a library for creating programs that use the IBM code page 437 character set and CGA color. This library would be useful for:

• Creating MS-DOS-looking programs.
• Creating retro-looking text-based games.
• An easy way to integrate retro-looking text, color, and sound into a retro-looking game.
• Learning programming in a way that includes a simple interface (use DOS_Screen) and has more interesting output (color and sound) than a modern terminal.

Simply include textmode.h and link with the TextMode library and SDL2.

#include <textmode.h>

cc main.c -lSDL2 -ltextmode

This library provides levels of flexibility, allowing simple rendering of CP437 characters, the creation of consoles that can be used within a regular program, to full, text mode programs.

Color

TextMode defines the symbols for the 16 CGA Colors, DOS_BLUE, DOS_BRIGHT_GREEN, etc, and general functions DOS_SetColor() and DOS_SetColorAlpha() that can be used for any rendering where CGA Color is needed.

#include <textmode.h>
...
SDL_Renderer * renderer;
...
DOS_SetColor(renderer, DOS_BLUE);
SDL_RenderDrawRect(renderer, &rect);

Sound

TextMode provides several functions to play PC-speaker-like beeps. To use sound in a program, first call DOS_InitSound().

DOS_InitSound();
...
DOS_Beep(); // just a basic beep
DOS_Sound(440, 1000); // A440 for 1000 ms
...
DOS_SoundAsync(440, 1000); // play a single pitch asychronously
...
// or, multiple pitches asychronously
DOS_QueueSound(440, 200);
DOS_QueueSound(550, 200);
DOS_QueueSound(660, 200);
DOS_QueueSound(880, 500);
DOS_PlayQueuedSound();
...
// play a series of musical notes with a BASIC-style PLAY string:
DOS_Play("t132 o5 l2 c l4 eg < b l8 b l16 > c d l4 c");

Basic Characters

For programs that need nothing more than some text here and there, TextMode provide functions for basic rendering of CP437 characters: DOS_RenderChar() and DOS_RenderString().

There are two styles of characters, normal (DOS_MODE80) and wide (DOS_MODE40).

#include <textmode.h>
...
SDL_Renderer * renderer;
...
DOS_SetColor(renderer, DOS_BRIGHT_GREEN);
DOS_RenderString(renderer, 0, 0, DOS_MODE80, "Hello, world");
SDL_RenderPresent(renderer);

Console

If you need a console that can be rendered anywhere within an SDL window, use a DOS_Console.

SDL_Renderer * renderer;
...
#define ROWS 10
#define COLS 15
DOS_Console * console = DOS_CreateConsole(COLS, ROWS, DOS_MODE80);
DOS_SetCursorType(DOS_CURSOR_FULL);
...
DOS_ClearScreen(); // clear to default attributes, cursor at 0, 0
DOS_GotoXY(2, 2);
DOS_SetForeground(DOS_CYAN);
DOS_PrintString("console size: %d x %d", COLS, ROWS);
...
DOS_RenderConsole(console, 0, 0);
SDL_RenderPresent(renderer);
...
DOS_DestroyConsole(console);

Screen

If you need a full MS-DOS-like text mode program with a multiple page console and colored border, use a DOS_InitScreen().

#include <textmode.h>
#include <SDL2/SDL.h>
#include <stdbool.h>

#define ROWS            25
#define COLS            80
#define BORDER_SIZE     4

int main()
{
    SDL_Init(SDL_INIT_VIDEO | SDL_INIT_AUDIO);
    DOS_InitScreen("My App", COLS, ROWS, DOS_MODE80, BORDER_SIZE);

    DOS_ClearScreen();
    DOS_GotoXY(5, 5);
    DOS_SetForeground(DOS_YELLOW);
    DOS_PrintString("Hey, Earth!");
    
    bool run = true;
    while ( run ) {
        DOS_LimitFrameRate(30);
        
        SDL_Event event;
        while ( SDL_PollEvent(&event) )
            if ( event.type == SDL_QUIT )
                run = false;

        DOS_DrawScreen();
    }
    
    SDL_Quit();
    return 0;
}