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8bitworkshop/presets/vcs/examples/piatable.a

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2016-12-16 01:21:51 +00:00
processor 6502
include "vcs.h"
include "macro.h"
include "xmacro.h"
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
seg.u Variables
org $80
Temp .byte
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
seg Code
org $f000
Start
CLEAN_START
lda #0
sta Temp
NextFrame
VERTICAL_SYNC
TIMER_SETUP 37
inc Temp
TIMER_WAIT
2018-12-06 14:41:45 +00:00
TIMER_SETUP 213
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lda Temp
and #$7f
jsr WaitForScanline
sta COLUBK
lda #180
jsr WaitForScanline
lda #0
sta COLUBK
lda #192
jsr WaitForScanline
jmp TimerDone
TimerDone
lda #0
sta COLUBK
TIMER_SETUP 30
TIMER_WAIT
jmp NextFrame
align $10
WaitForScanline subroutine
ldy INTIM ; Fetch timer value
.Wait
cpy INTIM
beq .Wait ; Wait for it to change
sta WSYNC ; Sync with scan line
cmp Timer2Scanline,y
bcs WaitForScanline
rts
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
align $100
Timer2Scanline
.byte 215, 0,214,213,212,211,210, 0,209,208,207,206,205,204, 0,203
.byte 202,201,200,199, 0,198,197,196,195,194, 0,193,192,191,190,189
.byte 188, 0,187,186,185,184,183, 0,182,181,180,179,178, 0,177,176
.byte 175,174,173,172, 0,171,170,169,168,167, 0,166,165,164,163,162
.byte 0,161,160,159,158,157,156, 0,155,154,153,152,151, 0,150,149
.byte 148,147,146, 0,145,144,143,142,141,140, 0,139,138,137,136,135
.byte 0,134,133,132,131,130, 0,129,128,127,126,125,124, 0,123,122
.byte 121,120,119, 0,118,117,116,115,114, 0,113,112,111,110,109,108
.byte 0,107,106,105,104,103, 0,102,101,100, 99, 98, 0, 97, 96, 95
.byte 94, 93, 92, 0, 91, 90, 89, 88, 87, 0, 86, 85, 84, 83, 82, 0
.byte 81, 80, 79, 78, 77, 76, 0, 75, 74, 73, 72, 71, 0, 70, 69, 68
.byte 67, 66, 0, 65, 64, 63, 62, 61, 60, 0, 59, 58, 57, 56, 55, 0
.byte 54, 53, 52, 51, 50, 0, 49, 48, 47, 46, 45, 44, 0, 43, 42, 41
.byte 40, 39, 0, 38, 37, 36, 35, 34, 0, 33, 32, 31, 30, 29, 28, 0
.byte 27, 26, 25, 24, 23, 0, 22, 21, 20, 19, 18, 0, 17, 16, 15, 14
.byte 13, 12, 0, 11, 10, 9, 8, 7, 0, 6, 5, 4, 3, 2, 0, 1
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
; Epilogue
org $fffc
.word Start
.word Start