graph.cpp

#include <bios.h>

/*
 * Graphic library for DOS
 * By Caiwan / Industrial Revolutioners
 *
*/

typedef unsigned char uchar;
typedef unsigned short ushort;
typedef unsigned int uint;

// sets 13h video mode (320x200)
void initgraph(){
    asm{
        mov ax, 13h
        int 10h
    }
}

// sets 10h default mode to text
void closegraph(){
    asm{
        mov ax, 10h
        int 10h
    }
}

//puts a pixel to a VRAM offset
void putpixel(ushort offs, uchar p){
    if (offs >= 320*200) return;
    asm {
        mov di, offs
        mov ax, 0xA000

        mov es, ax

        xor cx, cx
        xor ax, ax
        mov al, p

        stosb
    }
}

//puts a pixel to a specified xy coord
void putpixel(ushort x, ushort y, uchar p){
    putpixel (320*y+x, p);
}

//sets a palette token to a specified RGB color
void setpalette(uchar p, uchar r, uchar g, uchar b) {
    asm {
        xor bx, bx
        xor dx, dx
        xor cx, cx

        mov bl, p
        mov dh, r
        mov cl, g
        mov ch, b

        mov ax, 1010h
        int 10h
    }
}

/*
 * MAIN FUNCTION
 *
*/

int main(){
    // init graph
    initgraph();

    // generate a grazscale palette
    for (uchar i=0; i<255; i++){
        setpalette (i, i, i, i);
    }

    ushort kesz = 0;
    //...

    do {
        // draw a simple XOR texture
        for (ushort x = 0; x<320; x++)
            for(ushort y = 0; y<200; y++)
                putpixel(x, y, x^y);

    kesz = !_bios_keybrd(_KEYBRD_READY);
    } while (kesz);

    // release graphics and get back to DOS
    closegraph();
    return 0;
}