diff options
Diffstat (limited to 'buttons.asm')
| -rw-r--r-- | buttons.asm | 63 |
1 files changed, 63 insertions, 0 deletions
diff --git a/buttons.asm b/buttons.asm new file mode 100644 index 0000000..ed83074 --- /dev/null +++ b/buttons.asm @@ -0,0 +1,63 @@ +BUTTONS .rs 1 ; currently pressed buttons
+BUTTONS_TMP .rs 1 ; temporary variable for buttons
+LAST_KONAMI_BUTTON .rs 1 ; last button state for Konami Code check
+KONAMI_CODE_STATE .rs 1 ; Konami Code state
+KONAMI_CODE_TRIGGERED .rs 1 ; Konami Code triggered flag
+
+ ; controller reading, two times
+read_controller:
+ jsr .real ; first read
+ ldx <BUTTONS_TMP
+ jsr .real ; second read
+ cpx <BUTTONS_TMP ; lets compare values
+ bne .end ; ignore it if not equal
+ stx <BUTTONS ; storing value
+.end:
+ jsr konami_code_check
+ rts
+
+ ; real controller read, stores buttons to BUTTONS_TMP
+.real:
+ ;php
+ lda #1
+ sta $4016
+ lda #0
+ sta $4016
+ ldy #8
+.read_button:
+ lda $4016
+ and #$03
+ cmp #$01
+ ror <BUTTONS_TMP
+ dey
+ bne .read_button
+ rts
+
+konami_code_check:
+ ldy <KONAMI_CODE_STATE
+ lda <BUTTONS
+ beq .end
+ cmp <LAST_KONAMI_BUTTON
+ beq .end
+ cmp konami_code, y
+ bne .check_fail
+ iny
+ cpy #konami_code_length
+ bne .end
+ ldy #1
+ sty KONAMI_CODE_TRIGGERED
+ jmp .end
+.check_fail:
+ ldy #0
+ lda konami_code ; in case when newpressed button is first button of code
+ cmp <BUTTONS
+ bne .end
+ iny
+.end:
+ sty <KONAMI_CODE_STATE
+ sta <LAST_KONAMI_BUTTON
+ rts
+
+konami_code:
+ .db $10, $10, $20, $20, $40, $80, $40, $80, $02, $01
+konami_code_length .equ 10
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