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Applecorn
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Use ZP for SHR char plotting - little bit faster

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Bobbi Webber-Manners 2022-12-24 23:27:08 -05:00
parent a6b964b30e
commit acedd38cc1
2 changed files with 19 additions and 19 deletions
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applecorn.po
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38
auxmem.shr.s
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@ -113,6 +113,7 @@ SHRVDU22
* Write character to SHR screen
* On entry: A - character to write
* TODO: Make this faster!! It is horrible ATM
SHRPRCHAR SEC
SBC #32
STA ZP1+0 ; A*8 -> ZP1
@ -168,38 +169,37 @@ SHRCHAR320 PHY
* Draw one pixel row of font in 640 mode
* 2 bytes per char, 2 bits per pixel
SHRCHAR640 PHY
STZ :TEMP
STZ ZP2
LDX #$00 ; Source bit index
:L1 ASL ; MS bit -> C
PHP ; Preserve C
ROL :TEMP ; C -> LS bit
ROL ZP2 ; C -> LS bit
PLP ; Recover C
ROL :TEMP ; C -> LS bit
ROL ZP2 ; C -> LS bit
INX
CPX #$04
BNE :L1
CPX #$04
BNE :L1
PHA
LDA :TEMP
AND SHRCOLMASK ; Mask to set colour
STA [VDUADDR]
LDA ZP2
AND SHRCOLMASK ; Mask to set colour
STA [VDUADDR]
PLA
STZ :TEMP
LDX #$00
STZ ZP2
LDX #$00
:L2 ASL ; MS bit -> C
PHP ; Preserve C
ROL :TEMP ; C -> LS bit
ROL ZP2 ; C -> LS bit
PLP ; Recover C
ROL :TEMP ; C -> LS bit
ROL ZP2 ; C -> LS bit
INX
CPX #$04
BNE :L2
LDA :TEMP
LDY #$01
AND SHRCOLMASK ; Mask to set colour
STA [VDUADDR],Y
CPX #$04
BNE :L2
LDA ZP2
LDY #$01
AND SHRCOLMASK ; Mask to set colour
STA [VDUADDR],Y
PLY
RTS
:TEMP DB $00
* Calculate character address in SHR screen memory