Applecorn/auxmem.gfx.s
2021-09-29 10:21:04 -04:00

253 lines
7.1 KiB
ArmAsm

* AUXMEM.GFX.S
* (c) Bobbi 2021 GPLv3
*
* Graphics operations
*
* 26-Sep-2021 All graphics screen code moved to here.
* Write character to HGR screen
PRCHRSOFT CMP #$A0 ; Convert to screen code
BCS :B0
CMP #$80
BCC :B0
EOR #$80
:B0 TAX
AND #$20
BNE :B1
TXA
EOR #$40
TAX
:B1 PHX
JSR HCHARADDR ; Addr in VDUADDR
PHP ; Disable IRQs while
SEI ; toggling memory
STA $C004 ; Write to main
LDA VDUADDR+0
STA HGRADDR+0
LDA VDUADDR+1
STA HGRADDR+1
STA $C005 ; Write to aux
PLP ; Restore IRQs
PLA ; Recover character
>>> XF2MAIN,DRAWCHAR ; Plot char on HGR screen
PUTCHRET >>> ENTAUX
RTS
HSCR1LINE >>> XF2MAIN,HGRSCR1L
HSCR1RET >>> ENTAUX
RTS
HSCRCLREOL LDA VDUTEXTY
ASL
TAX
>>> WRTMAIN
LDA HGRTAB+0,X
STA HGRADDR+0
LDA HGRTAB+1,X
STA HGRADDR+1
>>> WRTAUX
>>> XF2MAIN,HCLRLINE
HSCRCLEAR >>> XF2MAIN,CLRHGR
VDU16RET >>> ENTAUX
STZ XPIXEL+0
STZ XPIXEL+1
LDA #191
STA YPIXEL
RTS
CLRLNRET >>> ENTAUX
RTS
* X=txt colour
HSCRSETTCOL RTS
* X=gfx colour, A=gcol action
* GCOL actions:
* 0 = SET pixel
* 1 = ORA with pixel
* 2 = AND with pixel
* 3 = XOR with pixel
* 4 = NOT pixel
* 5 = NUL no change to pixel
* 6 = CLR clear pixel to background
* 7 = UND undefined
HSCRSETGCOL PHX
LDX #$00 ; Normal drawing mode
CMP #$04 ; k=4 means toggle
BNE :NORM
LDX #$01 ; Change to toggle mode
:NORM >>> WRTMAIN
TXA
STX LINETYPE
STX FDRAWADDR+5
>>> WRTAUX
>>> XF2MAIN,SETLINE
VDU18RET1 >>> ENTAUX
:NORM PLA ; Colour
BPL :FOREGND ; <128 is foreground
>>> WRTMAIN
AND #$7F
STA BGCOLOR ; Stored in main memory
>>> WRTAUX
RTS
:FOREGND >>> WRTMAIN
STA FGCOLOR ; Stored in main memory
>>> WRTAUX
RTS
* Plot actions, PLOT k,x,y
* k is in VDUQ+4
* x is in VDUQ+5,VDUQ+6
* y is in VDUQ+7,VDUQ+8
HGRPLOT JSR CVTCOORD ; Convert coordinate system
HGRPLOT2 LDA VDUQ+4
AND #$04 ; Bit 2 set -> absolute
BNE HGRPLOTABS
JSR RELCOORD ; Add coords to XPIXEL/YPIXEL
HGRPLOTABS LDA VDUQ+4
AND #$03
CMP #$0 ; Bits 0,1 clear -> just move
BNE HGRPLOTACT
HGRPLOTPOS JMP HGRPOS ; Just update pos
HGRPLOTACT LDA VDUQ+4
AND #$C0
CMP #$40 ; Bit 7 clr, bit 6 set -> point
BNE :LINE
>>> WRTMAIN
LDA VDUQ+4
STA PLOTMODE
LDA VDUQ+5
STA FDRAWADDR+6 ; LSB of X1
LDA VDUQ+6
STA FDRAWADDR+7 ; MSB of X1
LDA VDUQ+7
STA FDRAWADDR+8 ; Y1
>>> WRTAUX
>>> XF2MAIN,DRAWPNT
:LINE >>> WRTMAIN
LDA VDUQ+4
STA PLOTMODE
LDA XPIXEL+0
STA FDRAWADDR+6
LDA XPIXEL+1
STA FDRAWADDR+7
LDA YPIXEL
STA FDRAWADDR+8
LDA VDUQ+5
STA FDRAWADDR+9 ; LSB of X1
LDA VDUQ+6
STA FDRAWADDR+10 ; MSB of X1
LDA VDUQ+7
STA FDRAWADDR+11 ; Y1
>>> WRTAUX
>>> XF2MAIN,DRAWLINE
VDU25RET >>> ENTAUX
* Fall through into HGRPOS
* Save pixel X,Y position
HGRPOS LDA VDUQ+5
STA XPIXEL+0
LDA VDUQ+6
STA XPIXEL+1
LDA VDUQ+7
STA YPIXEL
RTS
XPIXEL DW $0000 ; Previous plot x-coord
YPIXEL DW $0000 ; Previous plot y-coord
* Convert high-resolution screen coordinates
* from 1280x1024 to 280x192
CVTCOORD
* X-coordinate in VDUQ+5,+6 1280*7/32=280
LDA VDUQ+6 ; MSB of X-coord
CMP #$05 ; $500 is 1280
BCS :BIGX ; Value >=1280
STA ZP1+1 ; X-coord -> ZP1 and ZP2
STA ZP2+1
LDA VDUQ+5
STA ZP1+0
ASL A ; ZP2 *= 8
ROL ZP2+1
ASL A
ROL ZP2+1
ASL A
ROL ZP2+1
SEC ; ZP2-ZP1->ZP2
SBC ZP1+0
STA ZP2+0
LDA ZP2+1
SBC ZP1+1
LSR A ; ZP2 /= 32
ROR ZP2+0
LSR A
ROR ZP2+0
LSR A
ROR ZP2+0
LSR A
ROR ZP2+0
LSR A
ROR ZP2+0
STA VDUQ+6 ; ZP2 -> X-coord
LDA ZP2+0
STA VDUQ+5
* Y-coordinate in VDUQ+7,+8 1024*3/16=192
:YCOORD LDA VDUQ+8 ; MSB of Y-coord
AND #$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
ROL ZP2+1
CLC ; ZP2+ZP1->ZP2
ADC ZP1+0
STA ZP2+0
LDA ZP2+1
ADC ZP1+1
LSR A ; ZP2 /= 16
ROR ZP2+0
LSR A
ROR ZP2+0
:YCOORD4 LSR A
ROR ZP2+0
LSR A
ROR ZP2+0
STZ VDUQ+8 ; MSB always zero
SEC
LDA #191 ; 191 - ZP2 -> Y-coord
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
LDA XPIXEL+0
ADC VDUQ+5
STA VDUQ+5
LDA XPIXEL+1
ADC VDUQ+6
STA VDUQ+6
CLC
LDA YPIXEL
ADC VDUQ+7
STA VDUQ+7
RTS