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| author | Jesse Luehrs <doy@tozt.net> | 2014-10-04 21:23:15 -0400 |
|---|---|---|
| committer | Jesse Luehrs <doy@tozt.net> | 2014-10-04 21:23:15 -0400 |
| commit | 80f3c023c52fb1e25f8d832440cd5e11fe91a3bd (patch) | |
| tree | b313eea600b2ea0d5d5992014c82bb55f11bae50 | |
| parent | 8495ebe542903a4fb93f7bbb19fc4e53d050073b (diff) | |
| download | nes-snake-80f3c023c52fb1e25f8d832440cd5e11fe91a3bd.tar.gz nes-snake-80f3c023c52fb1e25f8d832440cd5e11fe91a3bd.zip | |
zero-page addressing for variables
| -rw-r--r-- | snake.s | 16 |
1 files changed, 8 insertions, 8 deletions
@@ -72,7 +72,7 @@ LoadPalettesLoop: ; initialize variables in ram LDA #$00 - STA buttons_pressed.w + STA buttons_pressed LDA #%00010000 ; enable sprites STA $2001 @@ -98,9 +98,9 @@ read_controller1_values: LDA $4016 AND #%00000001 - ASL buttons_pressed.w - ORA buttons_pressed.w - STA buttons_pressed.w + ASL buttons_pressed + ORA buttons_pressed + STA buttons_pressed INX JMP read_controller1_values @@ -111,25 +111,25 @@ NMI: JSR read_controller1 handle_up: - LDA buttons_pressed.w + LDA buttons_pressed AND #%00001000 CMP #$00 BEQ handle_down handle_down: - LDA buttons_pressed.w + LDA buttons_pressed AND #%00000100 CMP #$00 BEQ handle_left handle_left: - LDA buttons_pressed.w + LDA buttons_pressed AND #%00000010 CMP #$00 BEQ handle_right handle_right: - LDA buttons_pressed.w + LDA buttons_pressed AND #%00000001 CMP #$00 BEQ nmi_return |