diff options
| -rw-r--r-- | life.asm | 45 |
1 files changed, 27 insertions, 18 deletions
@@ -23,39 +23,49 @@ loop: cmp #$1d ; right arrow beq if_right - cmp #$9d ; left arrow beq if_left - jmp else_left -if_left: - jsr dec_num - jmp loop -else_left: + cmp #$2d ; reset if - pressed + beq if_reset + cmp #$20 ; fill cell if space pressed + beq if_space + cmp #$30 ; end program if 0 pressed + bne loop + jmp end - jsr print_byte if_right: jsr inc_num + jmp loop + +if_left: + jsr dec_num + jmp loop - cmp #$2d ; reset if - pressed - beq if_reset - jmp else_reset if_reset: - pha lda #$04 sta numH lda #$00 sta numL - pla jmp loop -else_reset: - cmp #$30 ; end program if 0 pressed - bne loop - jmp end +if_space: + ldx #$00 + lda (numL,x) + cmp #$a0 + beq if_cell_filled + jmp if_cell_empty +if_cell_filled: + lda #$20 + jsr print_byte + jmp loop +if_cell_empty: + lda #$a0 + jsr print_byte + jmp loop + ; loops until keyboard buffer has any number of characters in it key_wait: - ; init: pha to retrieve before rts, to keep A intact pha key_wait_loop: lda key_buf_len ; shows how many keys are in key buffer @@ -105,7 +115,6 @@ print_byte: txa ldy #$00 - sbc #$3f ; convert (very vaguely) to c64 screen codes sta (numL),y ; deinit: pull Y from stack and transfer original A from X to A |