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fire_tiny: shave a few more bytes off

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This commit is contained in:
Vince Weaver 2018-12-30 17:50:40 -05:00
parent 70ecf26c92
commit cc062df9c2
1 changed files with 9 additions and 8 deletions
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17
fire/fire_tiny.s
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@ -19,10 +19,11 @@
; 140 bytes -- start using zero-page addressing
; 139 bytes -- rotate instead of mask for low bit
; 138 bytes -- bcs instead of jmp
; 137 bytes -- BIT nop trick to get rid of jump
; 135 bytes -- push/pull instead of saving to zero page
; Zero Page
SEEDL = $4E
TEMP = $00
TEMPY = $01
; 100 = $64
@ -75,7 +76,7 @@ yloop:
xloop:
smc1:
lda $7d0,Y ; 3
sta TEMP ; 2
pha ; save on stack ; 1
and #$7 ; mask off ; 2
tax ; 1
@ -98,14 +99,14 @@ noEor: sta SEEDL
; end inlined RNG
ror ; shift into carry ; 1
bcc no_change ; 2
decrement:
lda <color_progression,X ; 2
bcs done_change ; 2
pla ; 1
bcs no_change ; 2
.byte $2c ; BIT trick, nops out next instruction
no_change:
lda TEMP ; 2
done_change:
lda <color_progression,X ; 2
smc2:
sta $750,Y ; 3