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entropy: another two bytes off thanks to qkumba

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Vince Weaver 2018-05-29 12:48:53 -04:00
parent c11bc7f5f6
commit d10d9cda5a
2 changed files with 3 additions and 4 deletions
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two-liners/entropy.dsk
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two-liners/entropy.s
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@ -24,6 +24,8 @@
; 135 bytes: store X to HGR_SCALE rather than TXA+STA
; 131 bytes: some fancy branch elimination by noticing X=1
; 126 bytes: nextx: simplify by using knowledge of possible x/y vals
; 124 bytes: qkumba noticed we can bump yloop up to include the
; pha, letting us remove two now unneeded stack ops
;BLT=BCC, BGE=BCS
@ -70,9 +72,8 @@ entropy:
eloop:
lda #4 ; FOR Y=4 to 189 STEP 6
pha ; YPOS stored on stack
yloop:
pha ; YPOS stored on stack
lda #4 ; FOR X=4 to 278 STEP 6
sta XPOS
lda #0 ; can't fit 278 in one byte, need overflow byte
@ -185,12 +186,10 @@ nexty: ; NEXT Y
pla ; YPOS on stack
adc #5 ; y+=6
; carry always set coming in, so only add 5
pha ; YPOS back on stack
cmp #189 ; see if less than 189
bcc yloop ; if so, loop
nexte: ; NEXT E
pla
inc EPOS
lda EPOS
cmp #15