MSX 仮想VRAM

wall.c

/*
z88dk / WebMSX
zcc +msx -lndos -create-app wall.c
bload"cas:",r
*/

#include <msx/gfx.h>

#define BYTE unsigned char

#define WIDTH 64
#define HEIGHT 48

const int dx[] = { 0, 0, 1, 1, 1, 0, -1, -1, -1 };
const int dy[] = { 0, -1, -1, 0, 1, 1, 1, 0, -1 };

BYTE vvr[WIDTH * HEIGHT] = { 0 };

void gen_wall()
{
    int lines[][] = {
        { 0, 0, 63, 0 },
        { 0, 23, 63, 23 },
        { 0, 47, 63, 47 },
        { 0, 0, 0, 47 },
        { 31, 0, 31, 47 },
        { 47, 24, 47, 47 },
        { 63, 0, 63, 47 }
    };

    for (int i = 0; i < 7; i++) {
        int x0 = lines[i][0];
        int y0 = lines[i][1];
        int x1 = lines[i][2];
        int y1 = lines[i][3];
        int w = x1 - x0;
        int h = y1 - y0;

        if (w >= h) {
            for (int j = x0; j <= x1; j++) {
                vvr[y0 * WIDTH + j] = 1;
            }
        } else {
            for (int j = y0; j <= y1; j++) {
                vvr[j * WIDTH + x0] = 1;
            }
        }
    }
}

void write_pgt()
{
    BYTE space[] = { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x02, 0x00 };
    BYTE wall[] = { 0xff, 0x81, 0xbd, 0xbd, 0xbd, 0xbd, 0x81, 0xff };

    // パターンジェネレータ・テーブル
    vwrite(space, 0, 8);
    vwrite(wall, 8, 8);
}

void main()
{
    int px = 0;
    int py = 0;

    gen_wall();
    set_mode(mode_1);
    write_pgt();

    while (! get_trigger(0)) {
        int st = get_stick(0);
        px += dx[st];
        py += dy[st];
        if (px < 0) px = 0;
        if (px > WIDTH-32) px = WIDTH-32;
        if (py < 0) py = 0;
        if (py > HEIGHT-24) py = HEIGHT-24;

        BYTE *src = vvr + (py * WIDTH + px);
        int dst = 0x1800;   // パターンネーム・テーブル
        for (int y = 0; y < 24; y++) {
            vwrite(src, dst, 32);
            src += WIDTH;
            dst += 32;
        }
    }
}

ROMカートリッジ版