; conway's game of life.

%import math
%import textio
%import emudbg

main {
    const ubyte WIDTH = 80
    const ubyte HEIGHT = 60-4
    const uword STRIDE = $0002+WIDTH
    uword world1 = memory("world1", (WIDTH+2)*(HEIGHT+2), 0)
    uword world2 = memory("world2", (WIDTH+2)*(HEIGHT+2), 0)
    uword @requirezp active_world = world1

   sub start() {
        ; cx16.set_screen_mode(3)
        txt.cls()
        txt.color(8)
        txt.plot(50,0)
        txt.print("prog8 - conway's game of life")
        sys.memset(world1, (WIDTH+2)*(HEIGHT+2), 0)
        sys.memset(world2, (WIDTH+2)*(HEIGHT+2), 0)

        set_start_gen()

        ubyte gen_add
        uword gen
        repeat {
            if gen_add==0
                cbm.SETTIM(0,0,0)

            next_gen()

            gen++
            txt.home()
            txt.color(5)
            txt.print(" gen ")
            txt.print_uw(gen)

            gen_add++
            if gen_add==10 {
                txt.print("  jiffies/10 gens: ")
                txt.print_uw(cbm.RDTIM16())
                txt.print("  ")
                gen_add=0
            }
        }
    }

    sub set_start_gen() {

; some way to set a custom start generation:
;        str start_gen = "                " +
;                        "                " +
;                        "                " +
;                        "          **    " +
;                        "        *    *  " +
;                        "       *        " +
;                        "       *     *  " +
;                        "       ******   " +
;                        "                " +
;                        "                " +
;                        "                " +
;                        "                " +
;                        "                " +
;                        "                " +
;                        "                " +
;                        "               "
;
;        for y in 0 to 15 {
;            for x in 0 to 15 {
;                if start_gen[y*16 + x]=='*'
;                    active_world[offset + x] = 1
;            }
;            offset += STRIDE
;        }

        ; randomize whole world
        uword offset = STRIDE+1
        ubyte x
        ubyte y
        for y in 0 to HEIGHT-1 {
            for x in 0 to WIDTH-1 {
                if math.rnd() & 1 == 1
                    active_world[offset+x] = 1
            }
            offset += STRIDE
        }
    }

    sub next_gen() {
        uword @requirezp new_world
        if active_world == world1
            new_world = world2
        else
            new_world = world1

        const ubyte DXOFFSET = 0
        const ubyte DYOFFSET = 2
        uword voffset = STRIDE+1-DXOFFSET
        uword offset

        ubyte x
        ubyte y
        for y in DYOFFSET to HEIGHT+DYOFFSET-1 {

            cx16.vaddr_autoincr(1, $b000 + 256*y, 0, 2)     ;  allows us to use simple Vera data byte assigns later instead of setchr() calls

            for x in DXOFFSET to WIDTH+DXOFFSET-1 {
                offset = voffset + x
                ubyte cell = active_world[offset]

                ; count the neighbors
                uword @requirezp ptr = active_world + offset - STRIDE - 1
                ubyte neighbors = @(ptr) + @(ptr+1) + @(ptr+2) +
                                  @(ptr+STRIDE) + cell + @(ptr+STRIDE+2) +
                                  @(ptr+STRIDE*2) + @(ptr+STRIDE*2+1) + @(ptr+STRIDE*2+2)

                ; apply game of life rules
                if neighbors==3
                    cell=1
                else if neighbors!=4
                    cell=0
                new_world[offset] = cell

                ; draw new cell
                if cell==0
                    ; txt.setchr(x, y, sc:' ')
                    cx16.VERA_DATA0 = sc:' '
                else
                    ; txt.setchr(x, y, sc:'●')
                    cx16.VERA_DATA0 = sc:'●'
            }
            voffset += STRIDE
        }

        active_world = new_world
    }
}