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Updating the demo.asm

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Safiire 2015-03-02 21:27:53 -08:00
parent d67d1a6693
commit 2dca12a519
1 changed files with 29 additions and 29 deletions
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58
demo.asm
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@ -119,7 +119,7 @@ init_sound:
;;;; ;;;;
; Clear page #2, which we'll use to hold sprite data ; Clear page #2, which we'll use to hold sprite data
; This subroutine clearlys hows why I need to have symbols ; This subroutine clearly shows why I need to have symbols
; to refer to bits of RAM in the zero page like dx, etc. ; to refer to bits of RAM in the zero page like dx, etc.
init_sprites: init_sprites:
lda #$00 lda #$00
@ -133,8 +133,8 @@ init_sprites:
lda #$70 lda #$70
sta $0200 ; sprite Y coordinate sta $0200 ; sprite Y coordinate
lda #$01 lda #$01
sta $0201 ; sprite + 1Pattern number sta $0201 ; sprite + 1 Pattern number
sta $0203 ; sprite+3 X coordinate sprite+2, color, stays 0. sta $0203 ; sprite + 3 X coordinate, sprite + 2, color, stays 0.
; Set initial value of dx ; Set initial value of dx
lda #$01 lda #$01
@ -243,38 +243,38 @@ react_to_input:
sta $01 ; Store the 1 in local variable 'a' so that we this is sta $01 ; Store the 1 in local variable 'a' so that we this is
jsr reverse_dx ; only called once per press. jsr reverse_dx ; only called once per press.
jmp a_done jmp a_done
not_a: not_a:
sta $01 ; A has been released, so put that zero into 'a'. sta $01 ; A has been released, so put that zero into 'a'.
a_done: a_done:
lda $4016 ; B does nothing lda $4016 ; B does nothing
lda $4016 ; Select does nothing lda $4016 ; Select does nothing
lda $4016 ; Start does nothing lda $4016 ; Start does nothing
lda $4016 ; Up lda $4016 ; Up
and #$01 and #$01
beq not_up beq not_up
ldx sprite ; Load Y value ldx sprite ; Load Y value
cpx #$07 cpx #$07
beq not_up ; No going past the top of the screen beq not_up ; No going past the top of the screen
dex dex
stx sprite stx sprite
not_up: not_up:
lda $4016 ; Down lda $4016 ; Down
and #$01 and #$01
beq not_dn beq not_dn
ldx sprite ldx sprite
cpx #$DF ; No going past the bottom of the screen. cpx #$DF ; No going past the bottom of the screen.
beq not_dn beq not_dn
inx inx
stx sprite stx sprite
not_dn: not_dn:
rts ; Ignore left and right, we don't use 'em rts ; Ignore left and right, we don't use 'em
reverse_dx: reverse_dx:
lda #$FF lda #$FF
eor $00 ; dx eor $00 ; dx Toggles between 0x1 and 0xfe (-1)
clc clc
adc #$01 adc #$01 ; add dx, and store to variable
sta $00 ; dx sta $00 ; dx
jsr low_c jsr low_c
rts rts