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Applecorn
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MODE 2 (SHR 320x200) point plotting implemented.

This commit is contained in:
Bobbi Webber-Manners 2022-12-30 17:54:30 -05:00
parent 6d48d2650c
commit 013e65c033
2 changed files with 26 additions and 10 deletions
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applecorn.po
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36
mainmem.shr.s
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@ -236,7 +236,30 @@ SHRPLOT >>> ENTMAIN
ROR A1L
LDY A1L ; Index into row of pixels
LDA SHRPIXELS ; Pixels per byte
CMP #$02 ; 2 is 320-mode (MODE 1)
BNE :MODE0
TXA
LSR
AND #$01 ; Keep LSB bit only
TAX ; Index into :BITS320
LDA :BITS320,X ; Get bit pattern for pixel to set
EOR #$FF ; Invert bits
AND [A3L],Y ; Load existing byte, clearing pixel
STA A1L
LDA :BITS320,X ; Get bit pattern for pixel to set
AND SHRGFXMASK ; Mask to set colour
ORA A1L ; OR into existing byte
* TODO: Apply SHRGFXACTION GCOL action
STA [A3L],Y ; Write to screen
>>> XF2AUX,GFXPLOTRET
RTS
:MODE0 TXA
AND #$03 ; Keep LSB two bits only
TAX ; Index into :BITS640
@ -253,6 +276,8 @@ SHRPLOT >>> ENTMAIN
STA [A3L],Y ; Write to screen
>>> XF2AUX,GFXPLOTRET
RTS
:BITS320 DB %11110000 ; Bit patterns for pixel ..
DB %00001111 ; .. within byte
:BITS640 DB %11000000 ; Bit patterns for pixel ..
DB %00110000 ; .. within byte
DB %00001100
@ -269,17 +294,8 @@ SHRCOORD PHP ; Disable interrupts
REP #$30 ; 16 bit M & X
MX %00 ; Tell Merlin
* X-coordinate in SHRVDUQ+5,+6 MODE0:1280/2=640 or MODE1:1280/4=320
LDA SHRPIXELS ; Pixels per byte
AND #$00FF
CMP #$02 ; 2 is 320-mode (MODE 1)
BNE :MODE0
* X-coordinate in SHRVDUQ+5,+6 1280/2=640
LDA SHRVDUQ+5
LSR ; /2
LSR ; /4
STA A1L ; Result in A1L/H
BRA :Y
:MODE0 LDA SHRVDUQ+5
LSR ; /2
STA A1L ; Result in A1L/H