SimpleRL DOS

#include <string.h>
#include <i86.h>

#define WIDTH 80

typedef struct {
    int x;
    int y;
} POINT;

void clear() {
    union REGS clear;
    union REGS hide;

    // clear screen
    clear.w.cx = 0;
    clear.w.dx = 0x1850;
    clear.h.bh = 7;
    clear.w.ax = 0x0600;
    int86(0x10, &clear, &clear);

    // hide cursor
    hide.h.ah = 0x01;
    hide.w.cx = 0x2607;
    int86(0x10, &hide, &hide);
}

void draw_char(char ch, int x, int y, char color) {
    int i;

    i = 2 * (y * WIDTH + x);
    ((char far *) 0xb8000000)[i] = ch;
    ((char far *) 0xb8000000)[i+1] = color;
}
void draw_line(char * line, int x, int y, int w, char color) {
    int ci;
    for (ci = 0; ci < w; ci++)
        draw_char(line[ci], x + ci, y, color);
}
void draw_map(char * map, int x, int y, int w, char color) {
    int h = strlen(map) / w;
    int line;

    for (line = 0; line < h; line++)
        draw_line(map + line * w, 0, line, w, 1);
}

void get_key(unsigned char * scancode, unsigned char * ascii) {
    union REGS getkey;
    getkey.h.ah = 0;
    int86(0x16, &getkey, &getkey);

    *scancode = getkey.h.ah;
    *ascii = getkey.h.al;
}

void move(char * map, POINT * p, int x, int y, int w) {
    if (map[y * w + x] == ' ') {
        p->x = x;
        p->y = y;
    }
}

void main() {
    char * map =
        "####  ####"
        "#  ####  #"
        "#        #"
        "##      ##"
        " #      # "
        " #      # "
        "##      ##"
        "#        #"
        "#  ####  #"
        "####  ####";
    int map_w = 10;

    POINT player = { 2, 2 };
    unsigned char scancode = 0;
    unsigned char ascii = 0;

    clear();
    draw_map(map, 0, 0, map_w, 5);

    do {
        draw_char(' ', player.x, player.y, 15);
        switch (scancode) {
        case 72:
            move(map, &player, player.x, player.y - 1,map_w);
            break;
        case 80:
            move(map, &player, player.x, player.y + 1,map_w);
            break;
        case 75:
            move(map, &player, player.x - 1, player.y,map_w);
            break;
        case 77:
            move(map, &player, player.x + 1, player.y,map_w);
            break;
        }
        draw_char('', player.x, player.y, 15);

        get_key(&scancode, &ascii);
    }while (scancode != 1);
}