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dos33fsprogs
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midline: clean up code

This commit is contained in:
Vince Weaver 2023-05-17 16:47:21 -04:00
parent 945244fdd0
commit 7294283e0f
1 changed files with 32 additions and 40 deletions
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72
vaporlock/demo/midline.s
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@ -11,26 +11,17 @@
midline:
; lda #0
; sta FRAME
; lda #$ff
; sta FRAMEH
;================================
; Clear screen and setup graphics
;================================
; jsr SETGR ; set lo-res 40x40 mode
; bit LORES
sta FULLGR
;====================================================
; setup text page2 screen of "Apple II Forever" text
;====================================================
; there are much better ways to accomplish this
sta SETMOUSETEXT
;====================================================
; setup text page1 screen of "Apple II Forever" text
;====================================================
ldy #0
restart:
ldx #0
@ -44,6 +35,34 @@ print_loop:
bne print_loop
print_done:
;==================================
; get exact vblank region
;==================================
; code by Sather
; "Understanding the Apple IIe"
poll1:
lda VBLANK ; Find end of VBL
bmi poll1 ; Fall through at VBL
poll2:
lda VBLANK
bpl poll2 ; Fall through at VBL' ; 2
lda $00 ; Now slew back in 17029 cycle loops ; 3
lp17029:
ldx #17 ; ; 2
jsr waitx1k ; ; 17000
jsr rts1 ; ; 12
lda $00 ; nop3 ; 3
lda $00 ; nop3 ; 3
lda VBLANK ; Back to VBL yet? ; 4
nop ; ; 2
bmi lp17029 ; no, slew back ; 2/3
;==============================
; do the cycle counting
;==============================
@ -76,26 +95,6 @@ delay_16_settext:
rts
.if 0
; -1
;==================================
; vblank = 4550 cycles
; Try X=226 Y=4 cycles=4545
skip_vblank:
lda $00 ; nop3
ldy #4 ; 2
loop3: ldx #226 ; 2
loop4: dex ; 2
bne loop4 ; 2nt/3
dey ; 2
bne loop3 ; 2nt/3
jmp midline_loop ; 3
;===================================
; wait y-reg times 10
;===================================
@ -129,13 +128,6 @@ waitx1k:
rts1:
rts ; 6
.include "vblank.s"
.endif
a2_string:
; 012345678901234567 8 9
; .byte "Apple II Forever!! ",'@'+$80," ",0