X-Git-Url: https://git.wirehaze.ovh/lifeboot.git/blobdiff_plain/0d9586ff094ca3530341657b0ded38e747286de8..996bd9ab6f26e318e4b678f4b11d81bb8a8c5164:/lifeboot.asm?ds=sidebyside diff --git a/lifeboot.asm b/lifeboot.asm index 2d1542f..8f11b87 100644 --- a/lifeboot.asm +++ b/lifeboot.asm @@ -1,31 +1,33 @@ bits 16 -org 0x7c00 +org 7c00h ; ============================================================================= ; settings -------------------------------------------------------------------- %define DEAD ' ' ; char to represent a dead cell -%define ALIVE '#' ; char to represent an alive cell -%define PRINT_COLOR 0x07 ; grey on black -%define WAIT_DELAY 0x02 ; 0.131072 seconds +%define ALIVE '.' ; char to represent an alive cell +%define PRINT_COLOR 07h ; grey on black + +%define WAIT_DELAY_CX 01h ; cx:dx = delay in microseconds +%define WAIT_DELAY_DX 00h ; constants ------------------------------------------------------------------- %define COLS 80 %define ROWS 25 -%define VGAPGSZ (COLS * ROWS * 2) +%define VGAPGSZ 1000h ; memory layout --------------------------------------------------------------- -%define ORG 0x7c00 -%define VGA 0xb8000 +%define ORG 7c00h +%define VGA 0b8000h %define DAT ORG + 512 ; static variables ------------------------------------------------------------ %define xss DAT ; xs() state (word) -%define currvgapg xss + 2 ; current vga page near pointer (word) +%define currvgapg DAT + 2 ; current vga page near pointer (word) ; ============================================================================= @@ -33,10 +35,10 @@ org 0x7c00 ; initialize segment registers mov ax, VGA >> 4 -mov ds, ax mov es, ax xor ax, ax +mov ds, ax mov ss, ax ; set stack pointers @@ -47,27 +49,41 @@ mov sp, bp cld ; disable cursor -mov ch, 0x3f ; cursor start and options -mov ah, 0x01 ; set text-mode cursor shape -int 0x10 ; video services +mov ch, 3fh ; cursor start and options +mov ah, 01h ; set text-mode cursor shape +int 10h ; video services ; initialize xss -mov ah, 0x00 ; get -int 0x1a ; system time + +set_xss_seed: + +mov ah, 00h ; get +int 1ah ; system time + +cmp dx, 0 +je set_xss_seed ; if seed is 0, xs wont work properly + mov [xss], dx ; cx:dx = number of clock ticks since midnight ; initialize currvgapg -mov word [currvgapg], VGAPGSZ +mov word [currvgapg], 0 -; setup ----------------------------------------------------------------------- +; start simulation from random state ------------------------------------------ -setup: +start: call init_grid -call flip_vga_page + +; apply game of life's rules to determine the next state ---------------------- + +next_state: + +call vsync_wait +call write_next_vga_page call delay +call flip_vga_page -jmp setup +jmp next_state ; ============================================================================= @@ -79,30 +95,30 @@ jmp setup delay: -mov cx, WAIT_DELAY ; cx:dx = interval in microseconds -mov dx, 0 +mov cx, WAIT_DELAY_CX +mov dx, WAIT_DELAY_DX -mov ah, 0x86 -int 0x15 ; wait +mov ah, 86h +int 15h ; wait ret -; vsync() - wait for display to enter the next VBlank cycle ------------------- +; vsync_wait() - wait for display to enter the next VBlank cycle -------------- ; clobbers ax, dx -vsync: +vsync_wait: -mov dx, 0x3da ; input status #1 register +mov dx, 3dah ; input status #1 register .wait_on: in al, dx - test al, 0x08 ; vertical retrace bit + test al, 08h ; vertical retrace bit jnz .wait_on .wait_off: in al, dx - test al, 0x08 + test al, 08h jz .wait_off ret @@ -165,13 +181,169 @@ ret flip_vga_page: -call vsync +call vsync_wait xor word [currvgapg], VGAPGSZ ; flip currvgapg setnz al ; al = !(currvgapg == 0) -mov ah, 0x05 ; select active display page -int 0x10 ; video services +mov ah, 05h ; select active display page +int 10h ; video services + +ret + +; alive_neighbours() ---------------------------------------------------------- + +; input: +; es:si -> current grid +; cx -> cell index + +; output: +; ax = # alive neighbours + +; clobbers ax, bx, dx + +alive_neighbours: +enter 5, 0 + +; [bp - 1]: row +; [bp - 2]: col +; [bp - 3]: neighbours +; [bp - 4]: i +; [bp - 5]: j + +mov ax, cx ; ax = idx +mov bl, COLS ; bl = COLS +div bl ; al = idx / COLS ; ah = idx % COLS + +mov [bp - 1], al ; row = idx / COLS +mov [bp - 2], ah ; row = idx % COLS +mov byte [bp - 3], 0 ; neighbours = 0 + +mov byte [bp - 4], -1 ; i = -1 +.i: ; do { + + mov byte [bp - 5], -1 ; j = -1 +.j: ; do { + + mov al, [bp - 4] + or al, [bp - 5] + jz .continue ; if (!i && !j) continue + + mov al, [bp - 1] + add al, [bp - 4] ; al = row + i + + cmp al, 0 + jl .continue ; if (row + i < 0) continue + + cmp al, ROWS + jge .continue ; if (row + i >= ROWS) continue + + mov ah, [bp - 2] + add ah, [bp - 5] ; ah = col + j + + cmp ah, 0 + jl .continue ; if (col + j < 0) continue + + cmp ah, COLS + jge .continue ; if (col + j >= COLS) continue + + movzx bx, ah ; bx = col + j + + mov ah, COLS + mul ah ; ax = (row + i) * COLS + + add bx, ax ; bx = cell index + shl bx, 1 ; bx = grid offset + + mov dx, [es:si + bx] ; dl = cell state + + cmp dl, ALIVE ; if (!ALIVE) continue + jne .continue + + inc byte [bp - 3] ; neighbours++ + +.continue: + inc byte [bp - 5] + cmp byte [bp - 5], 1 + jle .j ; } while (++j <= 1) + + inc byte [bp - 4] + cmp byte [bp - 4], 1 + jle .i ; } while (++i <= 1) + +movzx ax, byte [bp - 3] ; ax = # alive neighbours + +leave +ret + +; write_next_cell_state() ----------------------------------------------------- + +; input: +; es:si -> current grid +; es:di -> next grid +; cx -> cell index + +; output: +; [es:di + cx * 2] = updated cell state + +; clobbers ax, bx, dx + +write_next_cell_state: + +call alive_neighbours ; ax = # alive neighbours + +mov bx, cx +shl bx, 1 + +mov dx, [es:si + bx] ; dl = cell current state + +cmp dl, ALIVE ; if (ALIVE) { +jne .else + +cmp ax, 2 ; if (n < 2) +jl .dead ; return DEAD + +cmp ax, 3 ; if (n > 3) +jg .dead ; return DEAD + +jmp .alive ; return ALIVE + +.else: ; } + +cmp ax, 3 ; if (n != 3) +jne .dead ; return DEAD + +.alive: ; return ALIVE +mov dl, ALIVE +jmp .write + +.dead: +mov dl, DEAD + +.write: +mov [es:di + bx], dx + +ret + +; write_next_vga_page() ------------------------------------------------------- + +; clobbers di, si, ax, bx, cx, dx + +write_next_vga_page: + +mov si, [currvgapg] ; es:si -> current page + +mov di, VGAPGSZ +xor di, si ; es:di -> next page + +xor cx, cx ; i = 0 + +.update_loop: +call write_next_cell_state + +inc cx +cmp cx, COLS * ROWS +jl .update_loop ; for i in [0 .. COLS * ROWS - 1] ret @@ -186,4 +358,4 @@ jmp halt ; ============================================================================= times 510 - ($ - $$) db 0 ; fill remaining bytes with zeroes -dw 0xaa55 ; mbr magic byte +dw 0aa55h ; mbr magic byte