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kfest: got stable cycle count

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This commit is contained in:
Vince Weaver 2018-07-19 20:04:32 -04:00
parent f838c48968
commit 9481467748
1 changed files with 64 additions and 9 deletions
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73
kfest2018/raster.s
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@ -44,7 +44,7 @@ WAIT = $FCA8 ;; delay 1/2(26+27A+5A^2) us
; Clear Page1
lda #$4
sta DRAW_PAGE
lda #$00
lda #$44
jsr clear_gr
; draw border line
@ -53,6 +53,31 @@ WAIT = $FCA8 ;; delay 1/2(26+27A+5A^2) us
ldy #38
jsr hline
; temporarily draw HELLO
ldy CURRENT_OFFSET
ldx #0
data_loop2:
lda words,Y
sta $6d0,X
lda words2,Y
sta $750,X
lda words3,Y
sta $ad0,X
lda words4,Y
sta $b50,X
iny
inx
cpx #40
bne data_loop2
;=====================================================
; attempt vapor lock
; by reading the "floating bus" we can see most recently
@ -133,31 +158,61 @@ loopB:
; We want to alternate between page1 and page2 every 65 cycles
; vblank = 4550 cycles to do scrolling
; 2 + 48*( (4+2+25*(2+3)) + (4+2+23*(2+3)+4+5)) + 9)
; 48*[(6+125)-1] + [(6+115+10)-1]
display_loop:
ldy #96 ; 2
ldy #48 ; 2
outer_loop:
bit PAGE0 ; 4
ldx #25 ; 130 cycles with PAGE0 ; 2
page0_loop:
page0_loop: ; delay 126+bit
dex ; 2
bne page0_loop ; 2/3
bit PAGE0 ; 4
ldx #25 ; 130 cycles with PAGE1 ; 2
page1_loop:
bit PAGE1 ; 4
ldx #23 ; 130 cycles with PAGE1 ; 2
page1_loop: ; delay 115+(7 loop)+4 (bit)+4(extra)
dex ; 2
bne page1_loop ; 2/3
bit PAGE1 ; 4
nop ; 2
lda DRAW_PAGE ; 3
dey ; 2
bne outer_loop ; 2/3
jmp display_loop ; 3
; We have 4550 cycles in the vblank, use them wisely
; delay 4546 (+1 from loop falltrough, -2 for loadup, -3 for jmp)
; 4540 = x=9,y=89
; kill 3 cycles
lda DRAW_PAGE ; 3
lda DRAW_PAGE ; 3
ldy #89 ; 2
loop5:
ldx #9 ; 2
loop6:
dex ; 2
bne loop6 ; 2nt/3
dey ; 2
bne loop5 ; 2nt/3
jmp display_loop ; 3
ldy CURRENT_OFFSET
ldx #0
@ -235,7 +290,7 @@ words2:
.byte $0
.endrep
words3:
.byte $C9,$C0,$C9,$00, $C9,$C0,$00, $C9,$00,$00, $C9,$00,$00, $C9,$00,$C0,$00
.byte $C9,$C0,$C9,$00, $C9,$C0,$00, $C9,$00,$00, $C9,$00,$00, $C9,$00,$C9,$00
.repeat 239
.byte $0
.endrep