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Applecorn
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Char plotting works in MODE 0. No scroll yet.

This commit is contained in:
Bobbi Webber-Manners 2022-12-23 21:11:32 -05:00
parent cb74f75ad0
commit 0395d56012
2 changed files with 117 additions and 9 deletions
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applecorn.po
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126
auxmem.shr.s
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@ -21,7 +21,7 @@ PALETTE320 DB $00, $00 ; BLACK
DB $08, $00 ; BLUE
DB $08, $08 ; MAGENTA
DB $88, $00 ; CYAN
DB $80, $08 ; YELLOW
DB $88, $08 ; WHITE
DB $00, $00 ; BLACK
DB $00, $08 ; RED
DB $80, $00 ; GREEN
@ -29,7 +29,6 @@ PALETTE320 DB $00, $00 ; BLACK
DB $08, $00 ; BLUE
DB $08, $08 ; MAGENTA
DB $88, $00 ; CYAN
DB $80, $08 ; YELLOW
DB $88, $08 ; WHITE
PALETTE640 DB $00, $00 ; BLACK
@ -53,15 +52,13 @@ PALETTE640 DB $00, $00 ; BLACK
SHRVDU22 JSR VDU12 ; Clear text and SHR screen
LDA #$80 ; Most significant bit
TSB NEWVIDEO ; Enable SHR mode
LDA #$E1 ; SHR memory bank
STA VDUBANK
LDA VDUPIXELS ; Pixels per byte
CMP #$02 ; 2 is 320-mode (MODE 1)
BNE :MODE0
LDA SCB320 ; SCB for 320-mode
LDA #SCB320 ; SCB for 320-mode
LDY #00 ; Palette offset
BRA :S1
:MODE0 LDA SCB640 ; SCB for 640-mode
:MODE0 LDA #SCB640 ; SCB for 640-mode
LDY #32 ; Palette offset
:S1 LDX #$00
:L1 STAL $E19D00,X ; SCBs begin at $9D00 in $E1
@ -69,7 +66,7 @@ SHRVDU22 JSR VDU12 ; Clear text and SHR screen
CPX #200 ; 200 lines so 200 SCBs
BNE :L1
LDX #$00
:L2 LDA PALETTE320,Y ; Offset n Y computed above
:L2 LDA PALETTE320,Y ; Offset in Y computed above
STAL $E19E00,X ; Palettes begin at $9E00 in $E1
INX
INY
@ -79,13 +76,124 @@ SHRVDU22 JSR VDU12 ; Clear text and SHR screen
* Write character to SHR screen
SHRPRCHAR
* On entry: A - character to write
SHRPRCHAR SEC
SBC #32
STA ZP1+0 ; A*8 -> ZP1
STZ ZP1+1
ASL ZP1+0
ROL ZP1+1
ASL ZP1+0
ROL ZP1+1
ASL ZP1+0
ROL ZP1+1
CLC ; FONT8+A*8 -> ZP1
LDA ZP1+0
ADC #<FONT8
STA ZP1+0
LDA ZP1+1
ADC #>FONT8
STA ZP1+1
JSR SHRCHARADDR ; Addr in VDUADDR
LDY #$00 ; First row of char
:L1 >>> RDMAIN
LDA (ZP1),Y ; Load row of font
>>> RDAUX
LDX VDUPIXELS ; Pixels per byte
CPX #$02 ; 2 is 320-mode (MODE 1)
BNE :S1
JSR SHRCHAR320
BRA :S2
:S1 JSR SHRCHAR640
:S2 LDA VDUADDR+0 ; Add 160 to VDUADDR
CLC
ADC #160
STA VDUADDR+0
LDA VDUADDR+1
ADC #$00
STA VDUADDR+1
INY ; Next row of font
CPY #$08 ; Last row?
BNE :L1
RTS
* Draw one pixel row of font in 320 mode
* 4 bytes per char, 4 bits per pixel
SHRCHAR320 PHY
LDA #$FF
LDY #$00
STA [VDUADDR],Y
INY
STA [VDUADDR],Y
INY
STA [VDUADDR],Y
INY
STA [VDUADDR],Y
PLY
RTS
* Draw one pixel row of font in 640 mode
* 2 bytes per char, 2 bits per pixel
SHRCHAR640 PHY
STZ :TEMP
LDX #$00 ; Source bit index
:L1 ASL ; MS bit -> C
PHP ; Preserve C
ROL :TEMP ; C -> LS bit
PLP ; Recover C
ROL :TEMP ; C -> LS bit
INX
CPX #$04
BNE :L1
PHA
LDA :TEMP
AND #%10101010
STA [VDUADDR]
PLA
STZ :TEMP
LDX #$00
:L2 ASL ; MS bit -> C
PHP ; Preserve C
ROL :TEMP ; C -> LS bit
PLP ; Recover C
ROL :TEMP ; C -> LS bit
INX
CPX #$04
BNE :L2
LDA :TEMP
LDY #$01
AND #%10101010
STA [VDUADDR],Y
PLY
RTS
:TEMP DB $00
* Calculate character address in SHR screen memory
SHRCHARADDR
* This is the address of the first pixel row of the char
* Add $00A0 for each subsequent row
SHRCHARADDR LDA #$20 ; MSB starts at $20
LDY VDUTEXTY
:L1 CPY #$00
BEQ :S1
CLC
ADC #05 ; Each char row is $500
DEY
BRA :L1
:S1 STA VDUADDR+1 ; MSB of address
LDA VDUTEXTX
ASL ; Mult x 2 (4 pixels/byte)
LDY VDUPIXELS ; Pixels per byte
CPY #$02 ; 2 pixels per byte in 320 mode
BNE :S2
ASL ; Mult x 2 (2 pixels/byte)
:S2 STA VDUADDR+0 ; LSB of address
LDA #$E1 ; Bank $E1
STA VDUBANK
RTS
* (VDUADDR)=>character address, X=preserved
* Forwards scroll one line