video.c

/*
 * Copyright (C) 2015, Michiel Sikma <[email protected]>
 * MIT License
 */

#include "video.h"

byte *VGA = (byte *)0xA0000;          // Pointer to the video memory.
word *SYS_CLOCK = (word *)0x046C;     // The 18.2hz internal clock.

/**
 * Writes a single pixel directly to the video memory.
 */
void plot_pixel(int x, int y, byte color)
{
    VGA[(y << 8) + (y << 6) + x] = color;
}

/**
 * Sets the VGA mode.
 */
void set_mode(byte mode)
{
    union REGS regs;

    regs.h.ah = SET_MODE;
    regs.h.al = mode;
    int86(VIDEO_INT, &regs, &regs);
}