mirror of
https://github.com/deater/dos33fsprogs.git
synced 2024-06-09 22:29:36 +00:00
space_bars: some initial cycle-counting
it would help if I could subtract
This commit is contained in:
Vince Weaver
parent
9a88bc3121
commit
757f9d9c3d
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@ -2,6 +2,7 @@ include ../Makefile.inc
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DOS33 = ../dos33fs-utils/dos33
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PNG_TO_40x48D = ../gr-utils/png_to_40x48d
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B2D = ../bmp2dhr/b2d
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all: space_bars.dsk
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@ -16,7 +17,8 @@ SPACE_BARS: space_bars.o
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space_bars.o: space_bars.s instructions.s game.s \
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game_over.s gr_copy.s text_print.s title.s \
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spacebars_title.inc
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spacebars_title.inc \
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vapor_lock.s delay_a.s lz4_decode.s SB_BACKGROUNDC.BIN.lz4
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ca65 -o space_bars.o space_bars.s -l space_bars.lst
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####
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@ -24,6 +26,14 @@ space_bars.o: space_bars.s instructions.s game.s \
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spacebars_title.inc: ./images/spacebars_title_scaled.png
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$(PNG_TO_40x48D) asm ./images/spacebars_title_scaled.png spacebars_title > spacebars_title.inc
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####
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SB_BACKGROUNDC.BIN.lz4: SB_BACKGROUNDC.BIN
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lz4 -f -16 SB_BACKGROUNDC.BIN
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SB_BACKGROUNDC.BIN: sb_background.bmp
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$(B2D) sb_background.bmp HGR -d
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###
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clean:
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25
space_bars/delay_a.s
Normal file
25
space_bars/delay_a.s
Normal file
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@ -0,0 +1,25 @@
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; From http://6502org.wikidot.com/software-delay
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; 25+A cycles (including JSR), 19 bytes (excluding JSR)
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;
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; The branches must not cross page boundaries!
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;
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; Cycles Accumulator Carry flag
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; 0 1 2 3 4 5 6 (hex) 0 1 2 3 4 5 6
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; jsr delay_a ; 6 6 6 6 6 6 6 00 01 02 03 04 05 06
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dly0: sbc #7
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delay_a:cmp #7 ; 2 2 2 2 2 2 2 00 01 02 03 04 05 06 0 0 0 0 0 0 0
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bcs dly0 ; 2 2 2 2 2 2 2 00 01 02 03 04 05 06 0 0 0 0 0 0 0
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lsr ; 2 2 2 2 2 2 2 00 00 01 01 02 02 03 0 1 0 1 0 1 0
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bcs dly1 ; 2 3 2 3 2 3 2 00 00 01 01 02 02 03 0 1 0 1 0 1 0
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dly1: beq dly2 ; 3 3 2 2 2 2 2 00 00 01 01 02 02 03 0 1 0 1 0 1 0
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lsr ; 2 2 2 2 2 00 00 01 01 01 1 1 0 0 1
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beq dly3 ; 3 3 2 2 2 00 00 01 01 01 1 1 0 0 1
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bcc dly3 ; 3 3 2 01 01 01 0 0 1
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dly2: bne dly3 ; 2 2 3 00 00 01 0 1 0
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dly3: rts ; 6 6 6 6 6 6 6 00 00 00 00 01 01 01 0 1 1 1 0 0 1
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;
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; Total cycles: 25 26 27 28 29 30 31
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@ -1,14 +1,10 @@
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;================================
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; Show some instructions
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; return when a key is pressed
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; spacebars gameplay
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;================================
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game:
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;===================
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; init screen
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bit LORES
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bit SET_GR
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bit FULLGR
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bit KEYRESET
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;===================
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@ -17,11 +13,233 @@ game:
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lda #0
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sta DRAW_PAGE
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;=============================
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; Load graphic hgr
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lda #<background_hgr
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sta LZ4_SRC
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lda #>background_hgr
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sta LZ4_SRC+1
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lda #<(background_hgr_end-8) ; skip checksum at end
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sta LZ4_END
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lda #>(background_hgr_end-8) ; skip checksum at end
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sta LZ4_END+1
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lda #<$2000
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sta LZ4_DST
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lda #>$2000
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sta LZ4_DST+1
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jsr lz4_decode
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;=============================
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; Load graphic page0
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lda #$0c
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sta BASH
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lda #$00
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sta BASL ; load image to $c00
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; lda #<fs
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; sta GBASL
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; lda #>fs
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; sta GBASH
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; jsr load_rle_gr
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lda #4
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sta DRAW_PAGE
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jsr gr_copy_to_current ; copy to page1
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; GR part
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bit PAGE1
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bit LORES ; 4
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bit SET_GR ; 4
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bit FULLGR ; 4
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;=============================
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; Load graphic page1
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lda #$0c
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sta BASH
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lda #$00
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sta BASL ; load image to $c00
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; lda #<fs
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; sta GBASL
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; lda #>fs
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; sta GBASH
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; jsr load_rle_gr
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;===================
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; copy to page3
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lda #0
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jsr clear_gr
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sta DRAW_PAGE
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jsr gr_copy_to_current
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; GR part
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bit PAGE0
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jsr wait_until_keypressed ; tail call?
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;==============================
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; setup graphics for vapor lock
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;==============================
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rts
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jsr vapor_lock ; 6
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; vapor lock returns with us at beginning of hsync in line
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; 114 (7410 cycles), so with 5070 lines to go
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; so we have 5070 + 4550 = 9620 to kill
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jsr gr_copy_to_current ; 6+ 9292
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; now we have 322 left
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; GR part
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bit LORES ; 4
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bit SET_GR ; 4
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bit FULLGR ; 4
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; 322 - 12 = 310
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; - 3 for jmp
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; 307
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; Try X=9 Y=6 cycles=307
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ldy #6 ; 2
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sbloopA:ldx #9 ; 2
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sbloopB:dex ; 2
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bne sbloopB ; 2nt/3
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dey ; 2
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bne sbloopA ; 2nt/3
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jmp sb_begin_loop
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.align $100
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;================================================
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; Spacebars Loop
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;================================================
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; each scan line 65 cycles
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; 1 cycle each byte (40cycles) + 25 for horizontal
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; Total of 12480 cycles to draw screen
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; Vertical blank = 4550 cycles (70 scan lines)
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; Total of 17030 cycles to get back to where was
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sb_begin_loop:
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sb_display_loop:
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; 0-7 = text mode
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; 1 2 3
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;0123456789012345678901234567890123456789
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;LEVEL: 6 LIVES: 2 SCORE: 01978 HI: 02018
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; 8-47 = hgr
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; 48 - 191 = split .. 144 = 36grlins
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; 6 4 25+16+8+16 NNNNNNNN
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; 7 6 25+15+10+15 LNNNNNN
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; 8 8 25+14+12+14 NNNNNNN
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; 9 10 25+13+14+13 LNNNNN
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; 10 12 25+12+16+12
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; 11 14 25+11+18+11
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; 12 16 25+10+20+10
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; 13 18 25+09+22+09
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; 14 20 25+08+24+08
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; 15 22 25+07+26+07
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; 16 24 25+06+28+06
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; 17 26 25+05+30+05
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; 18 28 25+04+32+04
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; 19 30 25+03+34+03
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; 20 32 25+02+36+02
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; 21 34 25+01+38+01
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; 22 36 25+00
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; 23 38 25+12
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; 24 40 25+12
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; 8 lines of text mode
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ldy #8 ; 2
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sb_text_loop:
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bit SET_TEXT ; 4
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lda #29 ; 2
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jsr delay_a ; 25+29
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dey ; 2
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bne sb_text_loop ; 3
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;================
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; 65
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; -1
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sb_hgr_loop:
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; delay 184*65 = 11960
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; -2
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; +1
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; -8
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;=========================
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; 11951
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bit SET_GR ; 4
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bit HIRES ; 4
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; Try X=22 Y=103 cycles=11949 R2
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nop
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ldy #103 ; 2
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sbloopC:ldx #22 ; 2
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sbloopD:dex ; 2
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bne sbloopD ; 2nt/3
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dey ; 2
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bne sbloopC ; 2nt/3
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;======================================================
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; We have 4550 cycles in the vblank, use them wisely
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;======================================================
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; do_nothing should be 4550
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; -10 keypress
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; ===========
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; 4540
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; Try X=9 Y=89 cycles=4540
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ldy #89 ; 2
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sbloop1:ldx #9 ; 2
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sbloop2:dex ; 2
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bne sbloop2 ; 2nt/3
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dey ; 2
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bne sbloop1 ; 2nt/3
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lda KEYPRESS ; 4
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bpl sb_no_keypress ; 3
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jmp sb_start_over
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sb_no_keypress:
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jmp sb_display_loop ; 3
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sb_start_over:
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bit KEYRESET ; clear keypress ; 4
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rts ; 6
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;.include "deater.inc"
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background_hgr:
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.incbin "SB_BACKGROUNDC.BIN.lz4",11
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background_hgr_end:
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213
space_bars/lz4_decode.s
Normal file
213
space_bars/lz4_decode.s
Normal file
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@ -0,0 +1,213 @@
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; LZ4 data decompressor for Apple II
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; Code by Peter Ferrie (qkumba) (peter.ferrie@gmail.com)
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; "LZ4 unpacker in 143 bytes (6502 version) (2013)"
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; http://pferrie.host22.com/misc/appleii.htm
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; This is that code, but with comments and labels added for clarity.
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; I also found a bug when decoding with runs of multiples of 256
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; which has since been fixed upstream.
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; For LZ4 reference see
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; https://github.com/lz4/lz4/wiki/lz4_Frame_format.md
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; LZ4 summary:
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;
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; HEADER:
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; Should: check for magic number 04 22 4d 18
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; FLG: 64 in our case (01=version, block.index=1, block.checksum=0
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; size=0, checksum=1, reserved
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; MAX Blocksize: 40 (64kB)
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; HEADER CHECKSUM: a7
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; BLOCK HEADER: 4 bytes (le) length If highest bit set, uncompressed!
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; data (see below), followed by checksum?
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; BLOCKS:
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; Token byte. High 4-bits literal length, low 4-bits copy length
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; + If literal length==15, then following byte gets added to length
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; If that byte was 255, then keep adding bytes until not 255
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; + The literal bytes follow. There may be zero of them
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; + Next is block copy info. little-endian 2-byte offset to
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; be subtracted from current read position indicating source
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; + The low 4-bits of the token are the copy length, which needs
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; 4 added to it. As with the literal length, if it is 15 then
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; you read a byte and add (and if that byte is 255, keep adding)
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; At end you have 4 byte end-of-block marker (all zeros?) then
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; 4 bytes of checksum (if marked in flags)
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; our code does that, so be sure to set end -8
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;LZ4_SRC EQU $00
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;LZ4_DST EQU $02
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;LZ4_END EQU $04
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;COUNT EQU $06
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;DELTA EQU $08
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;UNPACK_BUFFER EQU $5E00 ; offset of first unpacked byte
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;======================
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; LZ4 decode
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;======================
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; input buffer in LZ4_SRC
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; output buffer hardcoded still
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; size in ENDH:ENDL
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lz4_decode:
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; lda LZ4_SRC ; packed data offset
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; clc
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; adc LZ4_END
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; sta LZ4_END
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; lda LZ4_SRC+1
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; adc LZ4_END+1
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; sta LZ4_END+1
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; lda #>UNPACK_BUFFER ; original unpacked data offset
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; sta LZ4_DST+1
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; lda #<UNPACK_BUFFER
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; sta LZ4_DST
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unpmain:
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ldy #0 ; used to index, always zero
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parsetoken:
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jsr getsrc ; get next token
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pha ; save for later (need bottom 4 bits)
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lsr ; number of literals in top 4 bits
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lsr ; so shift into place
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lsr
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lsr
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beq copymatches ; if zero, then no literals
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; jump ahead and copy
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jsr buildcount ; add up all the literal sizes
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; result is in ram[count+1]-1:A
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tax ; now in ram[count+1]-1:X
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jsr docopy ; copy the literals
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lda LZ4_SRC ; 16-bit compare
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cmp LZ4_END ; to see if we have reached the end
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lda LZ4_SRC+1
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sbc LZ4_END+1
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bcs done
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copymatches:
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jsr getsrc ; get 16-bit delta value
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sta DELTA
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jsr getsrc
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sta DELTA+1
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pla ; restore token
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and #$0f ; get bottom 4 bits
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; match count. 0 means 4
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; 15 means 19+, must be calculated
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jsr buildcount ; add up count bits, in ram[count+1]-:A
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clc
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adc #4 ; adjust count by 4 (minmatch)
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tax ; now in ramp[count+1]-1:X
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beq copy_no_adjust ; BUGFIX, don't increment if
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; exactly a multiple of 0x100
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bcc copy_no_adjust
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inc COUNT+1 ; increment if we overflowed
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copy_no_adjust:
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lda LZ4_SRC+1 ; save src on stack
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pha
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lda LZ4_SRC
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pha
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sec ; subtract delta
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lda LZ4_DST ; from destination, make new src
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sbc DELTA
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sta LZ4_SRC
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lda LZ4_DST+1
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sbc DELTA+1
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sta LZ4_SRC+1
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jsr docopy ; do the copy
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pla ; restore the src
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sta LZ4_SRC
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pla
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sta LZ4_SRC+1
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jmp parsetoken ; back to parsing tokens
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done:
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pla
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rts
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;=========
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; getsrc
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;=========
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; gets byte from src into A, increments pointer
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getsrc:
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lda (LZ4_SRC), Y ; get a byte from src
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inc LZ4_SRC ; increment pointer
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bne done_getsrc ; update 16-bit pointer
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inc LZ4_SRC+1 ; on 8-bit overflow
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done_getsrc:
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rts
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;============
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; buildcount
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;============
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buildcount:
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ldx #1 ; high count starts at 1
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stx COUNT+1 ; (loops at zero?)
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cmp #$0f ; if LITERAL_COUNT < 15, we are done
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bne done_buildcount
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buildcount_loop:
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sta COUNT ; save LITERAL_COUNT (15)
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jsr getsrc ; get the next byte
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tax ; put in X
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clc
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adc COUNT ; add new byte to old value
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bcc bc_8bit_oflow ; if overflow, increment high byte
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inc COUNT+1
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bc_8bit_oflow:
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inx ; check if read value was 255
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beq buildcount_loop ; if it was, keep looping and adding
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done_buildcount:
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rts
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;============
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; getput
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;============
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; gets a byte, then puts the byte
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getput:
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jsr getsrc
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; fallthrough to putdst
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;=============
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; putdst
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;=============
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; store A into destination
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putdst:
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sta (LZ4_DST), Y ; store A into destination
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inc LZ4_DST ; increment 16-bit pointer
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bne putdst_end ; if overflow, increment top byte
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inc LZ4_DST+1
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putdst_end:
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rts
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;=============================
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; docopy
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;=============================
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; copies ram[count+1]-1:X bytes
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; from src to dst
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docopy:
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docopy_loop:
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jsr getput ; get/put byte
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dex ; decrement count
|
||||
bne docopy_loop ; if not zero, loop
|
||||
dec COUNT+1 ; if zero, decrement high byte
|
||||
bne docopy_loop ; if not zero, loop
|
||||
|
||||
rts
|
||||
|
|
@ -8,6 +8,16 @@
|
|||
|
||||
; Zero Page
|
||||
FRAMEBUFFER = $00 ; $00 - $0F
|
||||
|
||||
;; LZ4 addresses
|
||||
|
||||
LZ4_SRC = $00
|
||||
LZ4_DST = $02
|
||||
LZ4_END = $04
|
||||
COUNT = $06
|
||||
DELTA = $08
|
||||
|
||||
|
||||
YPOS = $10
|
||||
YPOS_SIN = $11
|
||||
CH = $24
|
||||
|
|
@ -29,14 +39,18 @@ OUTH = $FF
|
|||
KEYPRESS= $C000
|
||||
KEYRESET= $C010
|
||||
SET_GR = $C050 ; Enable graphics
|
||||
SET_TEXT= $C051 ; Enable text
|
||||
FULLGR = $C052 ; Full screen, no text
|
||||
PAGE0 = $C054 ; Page0
|
||||
PAGE1 = $C055 ; Page1
|
||||
LORES = $C056 ; Enable LORES graphics
|
||||
HIRES = $C057 ; Enable HIRES graphics
|
||||
PADDLE_BUTTON0 = $C061
|
||||
PADDL0 = $C064
|
||||
PTRIG = $C070
|
||||
|
||||
|
||||
|
||||
; ROM routines
|
||||
|
||||
TEXT = $FB36 ;; Set text mode
|
||||
|
|
@ -129,6 +143,9 @@ gr_offsets:
|
|||
.include "game.s"
|
||||
.include "text_print.s"
|
||||
.include "game_over.s"
|
||||
.include "vapor_lock.s"
|
||||
.include "delay_a.s"
|
||||
.include "lz4_decode.s"
|
||||
|
||||
.include "spacebars_title.inc"
|
||||
|
||||
|
|
|
|||
|
|
@ -65,55 +65,7 @@ title_screen:
|
|||
;==============================
|
||||
; setup graphics for vapor lock
|
||||
;==============================
|
||||
|
||||
; Clear Page0
|
||||
lda #$0
|
||||
sta DRAW_PAGE
|
||||
lda #$44
|
||||
jsr clear_gr
|
||||
|
||||
; Make screen half green
|
||||
lda #$11
|
||||
ldy #24
|
||||
jsr clear_page_loop
|
||||
|
||||
|
||||
;=====================================================
|
||||
; attempt vapor lock
|
||||
; by reading the "floating bus" we can see most recently
|
||||
; written value of the display
|
||||
; we look for $55 (which is the grey line)
|
||||
;=====================================================
|
||||
; See:
|
||||
; Have an Apple Split by Bob Bishop
|
||||
; Softalk, October 1982
|
||||
|
||||
; Challenges: each scan line scans 40 bytes.
|
||||
; The blanking happens at the *beginning*
|
||||
; So 65 bytes are scanned, starting at adress of the line - 25
|
||||
|
||||
; the scan takes 8 cycles, look for 4 repeats of the value
|
||||
; to avoid false positive found if the horiz blanking is mirroring
|
||||
; the line (max 3 repeats in that case)
|
||||
|
||||
vapor_lock_loop: ; first make sure we have all zeroes
|
||||
LDA #$11
|
||||
zxloop:
|
||||
LDX #$04
|
||||
wiloop:
|
||||
CMP $C051
|
||||
BNE zxloop
|
||||
DEX
|
||||
BNE wiloop
|
||||
|
||||
LDA #$44 ; now look for our border color (4 times)
|
||||
zloop:
|
||||
LDX #$04
|
||||
qloop:
|
||||
CMP $C051
|
||||
BNE zloop
|
||||
DEX
|
||||
BNE qloop
|
||||
jsr vapor_lock
|
||||
|
||||
; found first line of black after green, at up to line 26 on screen
|
||||
; so we want roughly 22 lines * 4 = 88*65 = 5720 + 4550 = 10270
|
||||
|
|
|
|||
216
space_bars/vapor_lock.s
Normal file
216
space_bars/vapor_lock.s
Normal file
|
|
@ -0,0 +1,216 @@
|
|||
; This took a while to track down
|
||||
; On Apple II/II+ the horiz blanking addr are $1000 higher than on IIe
|
||||
; So on II+ were outside video area, so unlikely to be our set value
|
||||
; (unless I foolishly use $ff which some uninitialized mem is set to)
|
||||
; Lots of this color fiddling is to make sure you don't accidentally
|
||||
; get runs of colors on IIe due to the horiz blank
|
||||
|
||||
; 0-5 aqua 6-12 = grey, 13 - 20 = yellow, 21-23 = aqua rainbow 14
|
||||
;
|
||||
;
|
||||
;16 0 YA
|
||||
;17 1 YA
|
||||
;18 2 YA
|
||||
;19 3 YA
|
||||
;20 4 YA
|
||||
;21 5 AA
|
||||
;22 6 AG
|
||||
;23 7 AG
|
||||
;0 8 AG
|
||||
;1 9 AG
|
||||
;2 10 AG
|
||||
;3 11 AG
|
||||
;4 12 AG
|
||||
;5 13 AY ****
|
||||
;6 14 GY RAINBOW
|
||||
;7 15 GY
|
||||
;8 16 GY
|
||||
;9 17 GY
|
||||
;10 18 GY
|
||||
;11 19 GY
|
||||
;12 20 GY
|
||||
;13 21 YA
|
||||
;14 22 YA
|
||||
;15 23 YA
|
||||
|
||||
|
||||
|
||||
;==============================
|
||||
; setup graphics for vapor lock
|
||||
;==============================
|
||||
vapor_lock:
|
||||
|
||||
; Clear Page0
|
||||
lda #$0
|
||||
sta DRAW_PAGE
|
||||
lda #$ee ; full screen white $ff
|
||||
jsr clear_gr
|
||||
|
||||
lda #$dd
|
||||
ldy #40
|
||||
jsr clear_page_loop ; make top half grey2 $aa
|
||||
|
||||
lda #$aa
|
||||
ldy #24
|
||||
jsr clear_page_loop ; make top half grey2 $aa
|
||||
|
||||
lda #$ee
|
||||
ldy #10
|
||||
jsr clear_page_loop ; make top half grey2 $aa
|
||||
|
||||
; set up a rainbow to aid in exact lock
|
||||
|
||||
ldy #00
|
||||
rainbow_loop:
|
||||
tya
|
||||
sta $728+20,Y
|
||||
iny
|
||||
cpy #20
|
||||
bne rainbow_loop
|
||||
|
||||
;btt:
|
||||
; jmp btt
|
||||
|
||||
|
||||
;=====================================================
|
||||
; attempt vapor lock
|
||||
; by reading the "floating bus" we can see most recently
|
||||
; written value of the display
|
||||
;=====================================================
|
||||
; See:
|
||||
; Have an Apple Split by Bob Bishop
|
||||
; Softalk, October 1982
|
||||
|
||||
; Challenges: each scan line scans 40 bytes.
|
||||
; The blanking happens at the *beginning*
|
||||
; So 65 bytes are scanned, starting at adress of the line - 25
|
||||
|
||||
; the scan takes 8 cycles, look for 4 repeats of the value
|
||||
; to avoid false positive found if the horiz blanking is mirroring
|
||||
; the line (max 3 repeats in that case)
|
||||
|
||||
vapor_lock_loop:
|
||||
|
||||
; first make sure we have a full line of $aa
|
||||
|
||||
lda #$aa ; 2
|
||||
zxloop:
|
||||
ldx #$04 ; 2
|
||||
wiloop:
|
||||
cmp $C051 ; read the floating bus ; 4
|
||||
bne zxloop ; if not, start from scratch ; 2/3
|
||||
dex ; we were, dec ; 2
|
||||
bne wiloop ; if not 4 of them, restart ; 3/2
|
||||
|
||||
; if we get here we read 4 proper pixels, 11 apart (2+4+2+2+3)
|
||||
; 0 11 22 33, clock at 34
|
||||
; 1 12 23 34, clock at 35
|
||||
; 2 13 24 35, clock at 36
|
||||
; 3 14 25 36, clock at 37
|
||||
; 4 15 26 37, clock at 38
|
||||
; 5 16 27 38, clock at 39
|
||||
; 6 17 28 39, clock at 40
|
||||
|
||||
|
||||
; X X X X
|
||||
; X X X X
|
||||
; X X X X
|
||||
; X X X X
|
||||
; X X X X
|
||||
; X X X X
|
||||
; X X X X
|
||||
; 0123456789012345678901234 0123456789012345678901234567890123456789
|
||||
; 1 2 1 2 3
|
||||
; hsync pixels
|
||||
; XXXXXXXXXXXXXXXXXXXXXXXXX 4444444444444444444444444444440123456789
|
||||
|
||||
; now look for the color change that
|
||||
; happens at line 13*8 = 104
|
||||
|
||||
lda #$dd ; 2
|
||||
zloop:
|
||||
ldx #$04 ; 2
|
||||
qloop:
|
||||
cmp $C051 ; read floating bus ; 4
|
||||
bne zloop ; 2/3
|
||||
dex ; 2
|
||||
bne qloop ; 3/2
|
||||
;============
|
||||
; 11
|
||||
|
||||
; Found it!
|
||||
; if we get here we read 4 proper pixels, 11 apart (2+4+2+2+3)
|
||||
; 0 11 22 33, clock at 34
|
||||
; 1 12 23 34, clock at 35
|
||||
; 2 13 24 35, clock at 36
|
||||
; 3 14 25 36, clock at 37
|
||||
; 4 15 26 37, clock at 38
|
||||
; 5 16 27 38, clock at 39
|
||||
; 6 17 28 39, clock at 40
|
||||
|
||||
|
||||
; In theory near end of line 104
|
||||
|
||||
; now skip ahead 8 lines and read from the rainbow pattern we set
|
||||
; up to find our exact location
|
||||
|
||||
; delay 65 * 8 = 520
|
||||
; we back off a few to make sure we're not in the horiz blank
|
||||
; try to delay 510
|
||||
|
||||
lda #230 ; 2
|
||||
jsr delay_a ; delay 25+230 = 255
|
||||
|
||||
lda #226 ; 2
|
||||
jsr delay_a ; delay 25+226 = 251
|
||||
|
||||
|
||||
; now near end of line 112
|
||||
|
||||
|
||||
lda $C051 ; 4
|
||||
;kbb:
|
||||
; jmp kbb
|
||||
|
||||
; we are in theory on line $728 = 14*8 = 112
|
||||
; so 112*65 = 7280 cycles from start
|
||||
|
||||
; we are actualy 25+20+A pixels in
|
||||
; 7325+A
|
||||
|
||||
; Our goal is line 114 at 7410 cycles
|
||||
; 7410 - 7325 = 85
|
||||
|
||||
; so kill 85-A cycles
|
||||
; -6 to do subtraction
|
||||
; -6 for rts
|
||||
; -25 for delay_a overhead
|
||||
|
||||
eor #$ff ; 2
|
||||
sec ; 2
|
||||
adc #48 ; 2
|
||||
|
||||
jsr delay_a ; should total 48 cycles
|
||||
|
||||
|
||||
done_vapor_lock:
|
||||
rts ; 6
|
||||
|
||||
|
||||
|
||||
|
||||
; Some random related work
|
||||
; Docs:
|
||||
; Lancaster
|
||||
; Bishop
|
||||
; Sather
|
||||
|
||||
; Vaguely relevant but no help with the Apple II+ issue
|
||||
;
|
||||
; Eamon: Screen display and timing synchronization
|
||||
; on the Apple IIe and Apple IIgs
|
||||
;
|
||||
; Adams: Visually presented verbal stimuli by assembly
|
||||
; language on the Apple II computer.
|
||||
; Cavanagh and Anstis: Visual psychophysics on the
|
||||
; Apple II: Getting started
|
||||
Loading…
Reference in New Issue
Block a user