X-Git-Url: https://git.wirehaze.ovh/lifeboot.git/blobdiff_plain/1a5860dd84e2f3409daf770a67818a5997819711..365b1d68bca92b1f96187395e5bd2a4dc1a207c1:/lifeboot.asm?ds=sidebyside diff --git a/lifeboot.asm b/lifeboot.asm index b81453c..e44a671 100644 --- a/lifeboot.asm +++ b/lifeboot.asm @@ -1,5 +1,5 @@ bits 16 -org 0x7c00 +org 7c00h ; ============================================================================= @@ -7,19 +7,19 @@ org 0x7c00 %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 PRINT_COLOR 07h ; grey on black +%define WAIT_DELAY 02h ; 0.131072 seconds ; constants ------------------------------------------------------------------- %define COLS 80 %define ROWS 25 -%define VGAPGSZ (COLS * ROWS * 2) +%define VGAPGSZ (COLS * ROWS * 2 + 96) ; why 96 ?????? ; memory layout --------------------------------------------------------------- -%define ORG 0x7c00 -%define VGA 0xb8000 +%define ORG 7c00h +%define VGA 0b8000h %define DAT ORG + 512 ; static variables ------------------------------------------------------------ @@ -47,17 +47,24 @@ 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 ; start simulation from random state ------------------------------------------ @@ -69,10 +76,10 @@ call init_grid next_state: -call flip_vga_page ; display current state -call delay ; sleep a little - -call write_next_vga_page ; write the next state to the hidden page +call vsync_wait +call write_next_vga_page +call wait_keypress +call flip_vga_page jmp next_state @@ -89,8 +96,19 @@ delay: mov cx, WAIT_DELAY ; cx:dx = interval in microseconds mov dx, 0 -mov ah, 0x86 -int 0x15 ; wait +mov ah, 86h +int 15h ; wait + +ret + +; wait_keypress() - wait for any keypress ------------------------------------- + +; clobbers: ax + +wait_keypress: + +mov ah, 00h ; read key press +int 16h ; keyboard services ret @@ -100,16 +118,16 @@ ret 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 @@ -177,8 +195,8 @@ 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 @@ -191,7 +209,7 @@ ret ; output: ; ax = # alive neighbours -; clobbers ? +; clobbers ax, bx, dx alive_neighbours: enter 5, 0 @@ -208,25 +226,62 @@ 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 - 6], 0 ; neighbours = 0 +mov byte [bp - 3], 0 ; neighbours = 0 -mov byte [bp - 8], -1 ; i = -1 +mov byte [bp - 4], -1 ; i = -1 .i: ; do { - mov byte [bp - 10], -1 ; j = -1 + mov byte [bp - 5], -1 ; j = -1 .j: ; do { - ; if ((row || col) && get_state (grid, row + i, col + i) == ALIVE) - ; neighbours++ + 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 - inc byte [bp - 10] - cmp byte [bp - 10], 1 + 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 - 8] - cmp byte [bp - 8], 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 @@ -240,7 +295,7 @@ ret ; output: ; [es:di + cx * 2] = updated cell state -; clobbers ? +; clobbers ax, bx, dx write_next_cell_state: @@ -251,20 +306,20 @@ shl bx, 1 mov dx, [es:si + bx] ; dl = cell current state -test dl, ALIVE ; if (ALIVE) { +cmp dl, ALIVE ; if (ALIVE) { jne .else -test ax, 2 ; if (n < 2) +cmp ax, 2 ; if (n < 2) jl .dead ; return DEAD -test ax, 3 ; if (n > 3) +cmp ax, 3 ; if (n > 3) jg .dead ; return DEAD jmp .alive ; return ALIVE .else: ; } -test ax, 3 ; if (n != 3) +cmp ax, 3 ; if (n != 3) jne .dead ; return DEAD .alive: ; return ALIVE @@ -281,7 +336,7 @@ ret ; write_next_vga_page() ------------------------------------------------------- -; clobbers di, si, cx +; clobbers di, si, ax, bx, cx, dx write_next_vga_page: @@ -296,7 +351,7 @@ xor cx, cx ; i = 0 call write_next_cell_state inc cx -test cx, COLS * ROWS +cmp cx, COLS * ROWS jl .update_loop ; for i in [0 .. COLS * ROWS - 1] ret @@ -312,4 +367,4 @@ jmp halt ; ============================================================================= times 510 - ($ - $$) db 0 ; fill remaining bytes with zeroes -dw 0xaa55 ; mbr magic byte +dw 0aa55h ; mbr magic byte