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Clip out-of-range gfx coordinates.

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Bobbi Webber-Manners 2021-09-21 18:27:06 -04:00
parent c8e4940913
commit bf1229bfaa
2 changed files with 19 additions and 6 deletions
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BIN
applecorn.po
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25
auxmem.gfx.s
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@ -7,8 +7,10 @@
* from 1280x1024 to 280x192
CVTCOORD
* X-coordinate in VDUQ+5,+6 1280*7/32=280
LDA VDUQ+6 ; X-coord -> ZP1 and ZP2
STA ZP1+1
LDA VDUQ+6 ; MSB of X-coord
CMP #$05 ; $500 is 1280
BCS :BIGX ; Value >=1280
STA ZP1+1 ; X-coord -> ZP1 and ZP2
STA ZP2+1
LDA VDUQ+5
STA ZP1+0
@ -35,17 +37,20 @@ CVTCOORD
ROR ZP2+0
STA VDUQ+6 ; ZP2 -> X-coord
LDA ZP2+0
STA VDUQ+5
STA VDUQ+5
* Y-coordinate in VDUQ+7,+8 1024*3/16=192
LDA VDUQ+8 ; Y-coord -> ZP1
:YCOORD LDA VDUQ+8 ; MSB of Y-coord
AND #$FC
BNE :BIGY ; Y>1023
LDA VDUQ+8 ; Y-coord -> ZP1
STA ZP1+1
STA ZP2+1
LDA VDUQ+7
STA ZP1+0
ASL A ; ZP2 *= 2
ASL A ; ZP2 *= 2
ROL ZP2+1
CLC ; ZP2+ZP1->ZP2
CLC ; ZP2+ZP1->ZP2
ADC ZP1+0
STA ZP2+0
LDA ZP2+1
@ -64,6 +69,14 @@ CVTCOORD
SBC ZP2+0
STA VDUQ+7
RTS
:BIGY STZ VDUQ+7 ; Y too large, row zero
STZ VDUQ+8
RTS
:BIGX LDA #$17 ; X too large, use 279
STA VDUQ+5
LDA #$01
STA VDUQ+6
BRA :YCOORD
* Add coordinates to XPIXEL, YPIXEL
RELCOORD CLC