#if CBM_64 || CBM_264
const byte width = 40
const byte height = 25
#endif
#if ZX_SPECTRUM
const byte width = 32
const byte height = 24
#endif
#if ATARI_8
const byte width = 40
const byte height = 24
#endif

const word area = word(width) * word(height)

// representation: $1 live now $80 live soon
const byte ALIVE = $81
const byte DEAD = 0
array buffer [width * height] align(256)

void init_buffer() {
    pointer p
    for p,buffer.addr,paralleluntil,buffer.addr+area {
        p[0] = DEAD
    }
    // glider:
    buffer[1*width + 2] = ALIVE
    buffer[2*width + 3] = ALIVE
    buffer[3*width + 1] = ALIVE
    buffer[3*width + 2] = ALIVE
    buffer[3*width + 3] = ALIVE
}

void do_round() align(fast) {
    byte x, y, sum, j
    pointer p
    p = buffer.addr - width - 1
    for y,0,until,height {
        for x,0,until,width {
            sum = 0
            if y != 0 {
                if x != 0 { sum += p[0] }
                sum += p[1]
                if x != width - 1 { sum += p[2] }
            }
            if true {
                if x != 0 { sum += p[width] }
                if x != width - 1 { sum += p[width + 2] }
            }
            if y != height - 1 {
                if x != 0 { sum += p[2 * width] }
                sum += p[2 * width + 1]
                if x != width - 1 { sum += p[2 * width + 2] }
            }
            sum &= $7f
            if sum == 3 {
                p[width + 1] |= $80
            } else if sum != 2 {
                p[width + 1] &= $7f
            }
            p += 1
        }
    }
    p = buffer.addr
    for j,0,paralleluntil,height {
        for x,0,paralleluntil,width {
            if p[x] & $80 != 0 { p[x] = ALIVE }
            else { p[x] = DEAD }
        }
        p += width
    }
}


#if CBM_64

void init_gfx() {
    byte i
    for i,0,paralleluntil,250 {
        c64_color_ram[i+000]=light_blue
        c64_color_ram[i+250]=light_blue
        c64_color_ram[i+500]=light_blue
        c64_color_ram[i+750]=light_blue
    }
}

void redraw() align(fast) {
    pointer src, dest
    byte x, y
    src = buffer.addr
    dest = $400
    for y,0,until,height {
        for x,0,until,width {
            if src[x] != 0 {
                dest[x] = 128 + ' '
            } else {
                dest[x] = ' '
            }
        }
        src += width
        dest += width
    }
}

void wait_frame() align(fast) {
    while vic_raster != $ff {}
    while vic_raster == $ff {}
}
#endif

#if CBM_264

void init_gfx() {
}

void redraw() align(fast) {
    pointer src, dest
    byte x, y
    src = buffer.addr
    dest = $c00
    for y,0,until,height {
        for x,0,until,width {
            if src[x] != 0 {
                dest[x] = 128 + ' '
            } else {
                dest[x] = ' '
            }
        }
        src += width
        dest += width
    }
}

void wait_frame() align(fast) {
    while ted_raster_y != $ff {}
    while ted_raster_y == $ff {}
}
#endif

#if ATARI_8

pointer screen_start @$58
byte clock @$14

void init_gfx() {
}

void redraw() align(fast) {
    pointer src, dest
    byte x, y
    src = buffer.addr
    dest = screen_start
    for y,0,until,height {
        for x,0,until,width {
            if src[x] != 0 {
                dest[x] = 128 + ' 'scr
            } else {
                dest[x] = ' 'scr
            }
        }
        src += width
        dest += width
    }
}

void wait_frame() align(fast) {
    while clock != clock {}
}
#endif

#if ZX_SPECTRUM

void init_gfx() {
}

void redraw() align(fast) {
    pointer src, dest
    byte x, y
    src = buffer.addr
    dest = $5800
    for y,0,until,height {
        for x,0,until,width {
            if src[x] != 0 {
                dest[x] = 0
            } else {
                dest[x] = $3f
            }
        }
        src += width
        dest += width
    }
}

asm macro void wait_frame() {
    halt
}
#endif

void main() {
    init_gfx()
    init_buffer()
    redraw()
    while true {
        wait_frame()
        do_round()
        redraw()
    }
}