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cc65/libsrc/vic20/tgi/vic20-hi.s

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;
; Graphics driver for a 160x192x2 mode on the VIC-20.
;
; Based on C64 TGI driver
;
; 2018-03-11, Sven Michael Klose
; 2020-07-06, Greg King
;
.include "zeropage.inc"
.include "vic20.inc"
.include "tgi-kernel.inc"
.include "tgi-error.inc"
.macpack generic
.macpack module
; ------------------------------------------------------------------------
; Constants
COLS = 20
ROWS = 12
XRES = COLS * 8
YRES = ROWS * 16
TGI_IOCTL_VIC20_SET_PATTERN = $01
; ------------------------------------------------------------------------
; Header. Includes jump table and constants.
module_header _vic20_hi_tgi
; First part of the header is a structure that has a magic and defines the
; capabilities of the driver
.byte $74, $67, $69 ; ASCII "tgi"
.byte TGI_API_VERSION ; TGI API version number
.addr $0000 ; Library reference
.word XRES ; X resolution
.word YRES ; Y resolution
.byte 2 ; Number of drawing colors
.byte 1 ; Number of screens available
.byte 8 ; System font X size
.byte 8 ; System font Y size
.word $0180 ; Aspect ratio 2.5:3
.byte 0 ; TGI driver flags
; Next comes the jump table. With the exception of IRQ, all entries must be
; valid and may point to an RTS for test versions (function not implemented).
.addr INSTALL
.addr UNINSTALL
.addr INIT
.addr DONE
.addr GETERROR
.addr CONTROL
.addr CLEAR
.addr SETVIEWPAGE
.addr SETDRAWPAGE
.addr SETCOLOR
.addr SETPALETTE
.addr GETPALETTE
.addr GETDEFPALETTE
.addr SETPIXEL
.addr GETPIXEL
.addr LINE
.addr BAR
.addr TEXTSTYLE
.addr OUTTEXT
; ------------------------------------------------------------------------
; Data.
; Variables mapped to the zero-page segment variables. Some of these are
; used for passing parameters to the driver.
X1 := ptr1
Y1 := ptr2
X2 := ptr3
Y2 := ptr4
TEXT := ptr3
POINT := regsave
SOURCE := tmp1
DEST := tmp3
; Absolute variables used in the code
.bss
ERROR: .res 1 ; Error code
PALETTE: .res 2 ; The current palette
CURCOL: .res 1 ; Current color.
BITMASK: .res 1 ; $00 = clear, $FF = set pixels
; BAR variables
XPOSR: .res 1 ; Used by BAR.
PATTERN: .res 2 ; Address of pattern.
USERPATTERN: .res 2 ; User-defined pattern set via CONTROL.
COUNTER: .res 2
TMP: .res 1
MASKS: .res 1
MASKD: .res 1
XCPOS: .res 1
HEIGHT: .res 1
; Line variables
CHUNK := X2 ; Used in the line routine
OLDCHUNK := X2+1 ; Ditto
TEMP := tmp4
TEMP2 := sreg
DX: .res 2
DY: .res 2
; Text output stuff
TEXTMAGX: .res 1
TEXTMAGY: .res 1
TEXTDIR: .res 1
; Constants and tables
.rodata
DEFPALETTE: .byte $00, $01 ; White on black
PALETTESIZE = * - DEFPALETTE
BITTAB: .byte $80, $40, $20, $10, $08, $04, $02, $01
BITCHUNK: .byte $FF, $7F, $3F, $1F, $0F, $07, $03, $01
CHARROM := $8000 ; Character ROM base address
CBASE := $9400 ; Color memory base address
SBASE := $1000 ; Screen memory base address
VBASE := $1100 ; Video memory base address
; These numbers are added to Kernal's default VIC settings.
; They make the Video Interface Controller show graphics instead of text.
.proc VICREGS
.byte <+2 ; Left_edge + 2
.byte <-2 ; Top_edge - 2
.byte <-2 ; Columns - 2
.byte <-(11 << 1) + 1 ; Rows - 11, chars. are 8 x 16 pixels
.byte 0
.byte <+$0C ; Font_address = $1000
.endproc
XADDRS_L:
.repeat COLS, n
.byte <(VBASE + YRES * n)
.endrep
XADDRS_H:
.repeat COLS, n
.byte >(VBASE + YRES * n)
.endrep
MASKS_LEFT:
.byte %11111111
MASKD_RIGHT:
.byte %01111111
.byte %00111111
.byte %00011111
.byte %00001111
.byte %00000111
.byte %00000011
.byte %00000001
MASKD_LEFT:
.byte %00000000
MASKS_RIGHT:
.byte %10000000
.byte %11000000
.byte %11100000
.byte %11110000
.byte %11111000
.byte %11111100
.byte %11111110
.byte %11111111
PATTERN_EMPTY:
.byte %00000000
.byte %00000000
.byte %00000000
.byte %00000000
.byte %00000000
.byte %00000000
.byte %00000000
.byte %00000000
PATTERN_SOLID:
.byte %11111111
.byte %11111111
.byte %11111111
.byte %11111111
.byte %11111111
.byte %11111111
.byte %11111111
.byte %11111111
.code
; ------------------------------------------------------------------------
; INSTALL routine. Is called after the driver is loaded into memory. May
; initialize anything that has to be done just once. Is probably empty
; most of the time.
;
; Must set an error code: NO
;
.proc INSTALL
; Reset user-defined pattern.
lda #$00
sta PATTERN
sta PATTERN+1
rts
.endproc
; ------------------------------------------------------------------------
; UNINSTALL routine. Is called before the driver is removed from memory. May
; clean up anything done by INSTALL; but is probably empty most of the time.
;
; Must set an error code: NO
;
.proc UNINSTALL
rts
.endproc
; ------------------------------------------------------------------------
; INIT: Changes an already installed device from text mode to graphics
; mode.
; Note that INIT/DONE may be called multiple times while the driver
; is loaded, while INSTALL is called only once, so any code that is needed
; to initialize variables and so on must go here. Setting the palette
; is not needed because that is done by the graphics kernel later.
; The graphics kernel never will call INIT when a graphics mode already is
; active; so, there is no need to protect against that.
;
; Must set an error code: YES
;
.proc INIT
; Initialize variables
ldx #$FF
stx BITMASK
; Make screen columns.
lda #<SBASE
sta tmp2
lda #>SBASE
sta tmp2+1
inx ; (ldx #$00)
stx ERROR ; Set to TGI_ERR_OK
@NEXT_ROW:
ldy #$00
txa
clc
adc #$10
@NEXT_COLUMN:
sta (tmp2),y
clc
adc #ROWS
iny
cpy #COLS
bne @NEXT_COLUMN
; Step to next row on screen.
lda tmp2
clc
adc #COLS
sta tmp2
bcc @L1
inc tmp2+1
@L1: inx
cpx #ROWS
bne @NEXT_ROW
; Set up VIC.
ldx #.sizeof(VICREGS) - 1
@L2: clc
lda $EDE4,x
adc VICREGS,x
sta VIC,x
dex
bpl @L2
jmp CLEAR
.endproc
; ------------------------------------------------------------------------
; DONE: Will be called to switch the graphics device back into text mode.
; The graphics kernel never will call DONE when no graphics mode is active;
; so, there is no need to protect against that.
;
; Must set an error code: NO
;
.proc DONE
jmp $E518 ; Kernal console init.
.endproc
; ------------------------------------------------------------------------
; GETERROR: Return the error code in A, and clear it.
.proc GETERROR
ldx #TGI_ERR_OK
lda ERROR
stx ERROR
rts
.endproc
; ------------------------------------------------------------------------
; CONTROL: Platform-/driver-specific entry point.
;
; Must set an error code: YES
;
.proc CONTROL
; Set user-defined pattern.
cmp #TGI_IOCTL_VIC20_SET_PATTERN
bne @INVALID_FUNC
lda ptr1
sta USERPATTERN
lda ptr1+1
sta USERPATTERN+1
lda #TGI_ERR_OK
.byte $2C ;(bit $1234)
; Return with error code for invalid function index.
@INVALID_FUNC:
lda #TGI_ERR_INV_FUNC
sta ERROR
rts
.endproc
; ------------------------------------------------------------------------
; CLEAR: Clears the screen. All pixels are set to the background color.
;
; Must set an error code: NO
;
.proc CLEAR
lda #%00000000
tay ; (ldy #$00)
@L1: sta VBASE + $0000,y
sta VBASE + $0100,y
sta VBASE + $0200,y
sta VBASE + $0300,y
sta VBASE + $0400,y
sta VBASE + $0500,y
sta VBASE + $0600,y
sta VBASE + $0700,y
sta VBASE + $0800,y
sta VBASE + $0900,y
sta VBASE + $0A00,y
sta VBASE + $0B00,y
sta VBASE + $0C00,y
sta VBASE + $0D00,y
sta VBASE + $0E00,y
iny
bne @L1
rts
.endproc
; ------------------------------------------------------------------------
; SETVIEWPAGE: Set the visible page. Called with the new page in .A (0..n).
; The page number already is checked, to be valid, by the graphics kernel.
;
; Must set an error code: NO (will be called only if page OK)
;
.proc SETVIEWPAGE
rts
.endproc
; ------------------------------------------------------------------------
; SETDRAWPAGE: Set the drawable page. Called with the new page in .A (0..n-1).
; The page number already is checked, to be valid, by the graphics kernel.
;
; Must set an error code: NO (will be called only if page OK)
;
.proc SETDRAWPAGE
rts
.endproc
; ------------------------------------------------------------------------
; SETCOLOR: Set the drawing color (in .A). The new color already is checked
; to be in a valid range (0..maxcolor).
;
; Must set an error code: NO (will be called only if color OK)
;
.proc SETCOLOR
sta CURCOL
tax
beq @L1
lda #$FF
@L1: sta BITMASK
rts
.endproc
; ------------------------------------------------------------------------
; SETPALETTE: Set the palette (not available with all drivers/hardware).
; A pointer to the palette is passed in ptr1. Must set an error if palettes
; are not supported
;
; Must set an error code: YES
;
.proc SETPALETTE
ldy #PALETTESIZE - 1
@L1: lda (ptr1),y ; Copy the palette
and #$0F ; Make a valid color
sta PALETTE,y
dey
bpl @L1
; Initialize the color map with the new color settings.
iny ; Set .Y to $00
lda PALETTE+1 ; Foreground color
@L2: sta CBASE + $0000,y
sta CBASE + $0100,y
iny
bne @L2
lda PALETTE ; Background color
asl a ; Put it in high nybble
asl a
asl a
asl a
sta tmp2
lda VIC_COLOR
and #$0F
ora tmp2
sta VIC_COLOR
; Done, reset the error code
;ldy #TGI_ERR_OK ; (Already zero)
sty ERROR
rts
.endproc
; ------------------------------------------------------------------------
; GETPALETTE: Return the current palette in ".XA". Even drivers that cannot
; set the palette should return the default palette here; so, there's no
; way for this function to fail.
;
; Must set an error code: NO
;
.proc GETPALETTE
lda #<PALETTE
ldx #>PALETTE
rts
.endproc
; ------------------------------------------------------------------------
; GETDEFPALETTE: Return the default palette for the driver in ".XA". All
; drivers should return something reasonable here, even drivers that don't
; support palettes; otherwise, the caller has no way to determine the colors
; of the (not changeable) palette.
;
; Must set an error code: NO (all drivers must have a default palette)
;
.proc GETDEFPALETTE
lda #<DEFPALETTE
ldx #>DEFPALETTE
rts
.endproc
; ------------------------------------------------------------------------
; SETPIXEL: Draw one pixel at X1/Y1 = ptr1/ptr2 with the current drawing
; color. The co-ordinates passed to this function never are outside the
; visible screen area; so, there's no need for clipping inside this function.
;
; Must set an error code: NO
;
.proc SETPIXEL
jsr CALC ; Calculate co-ordinates
ldy #$00
lda (POINT),Y
eor BITMASK
and BITTAB,X
eor (POINT),Y
sta (POINT),Y
rts
.endproc
; ------------------------------------------------------------------------
; GETPIXEL: Read the color value of a pixel; and return it in ".XA". The
; co-ordinates passed to this function never are outside the visible screen
; area; so, there's no need for clipping inside this function.
.proc GETPIXEL
jsr CALC ; Calculate co-ordinates
ldy #$00
lda (POINT),Y
and BITTAB,X
beq @L1
iny
tya ; Get color value into .A
@L1: ldx #>$0000 ; Clear high byte
rts
.endproc
; ------------------------------------------------------------------------
; TEXTSTYLE: Set the style used when calling OUTTEXT. Text scalings in x and y
; directions are passed in .X/.Y; the text direction is passed in .A.
;
; Must set an error code: NO
;
.proc TEXTSTYLE
stx TEXTMAGX
sty TEXTMAGY
sta TEXTDIR
rts
.endproc
; ------------------------------------------------------------------------
; OUTTEXT: Output text at X/Y = ptr1/ptr2 using the current color and the
; current text style. The text to output is given as a zero-terminated
; string with address in ptr3.
;
; Must set an error code: NO
;
.proc OUTTEXT
rts
.endproc
; ------------------------------------------------------------------------
; Calculate address and X offset in char. line, to plot the pixel at X1/Y1.
.proc CALC
lda X1+1
bne @L1
lda Y1+1
bne @L1
lda X1
lsr
lsr
lsr
tay
lda XADDRS_L,y
clc
adc Y1
sta POINT
lda XADDRS_H,y
adc #$00
sta POINT+1
lda X1
and #7
tax
@L1: rts
.endproc
; ------------------------------------------------------------------------
; LINE: Draw a line from X1/Y1 to X2/Y2, where X1/Y1 = ptr1/ptr2 and
; X2/Y2 = ptr3/ptr4 using the current drawing color.
;
; X1,X2 etc. are set up above (x2=LINNUM in particular)
; Format is LINE x2,y2,x1,y1
;
; Must set an error code: NO
;
.proc LINE
@CHECK: lda X2 ; Make sure x1 < x2
sec
sbc X1
tax
lda X2+1
sbc X1+1
bpl @CONT
lda Y2 ; If not, swap P1 and P2
ldy Y1
sta Y1
sty Y2
lda Y2+1
ldy Y1+1
sta Y1+1
sty Y2+1
lda X1
ldy X2
sty X1
sta X2
lda X2+1
ldy X1+1
sta X1+1
sty X2+1
bcc @CHECK
@CONT: sta DX+1
stx DX
ldx #$C8 ; INY
lda Y2 ; Calculate dy
sec
sbc Y1
tay
lda Y2+1
sbc Y1+1
bpl @DYPOS ; Is y2 >= y1?
lda Y1 ; Otherwise, dy = y1 - y2
sec
sbc Y2
tay
ldx #$88 ; DEY
@DYPOS: sty DY ; 8-bit DY -- FIX ME?
stx YINCDEC
stx XINCDEC
lda X1
lsr
lsr
lsr
tay
lda XADDRS_L,y
sta POINT
lda XADDRS_H,y
sta POINT+1
ldy Y1
lda X1
and #7
tax
lda BITCHUNK,X
sta OLDCHUNK
sta CHUNK
ldx DY
cpx DX ; Who's bigger: dy or dx?
bcc STEPINX ; If dx, then...
lda DX+1
bne STEPINX
;
; Big steps in Y
;
; X is now counter, Y is y co-ordinate
;
; On entry, X=DY=number of loop iterations, and Y=Y1
STEPINY:
lda #$00
sta OLDCHUNK ; So plotting routine will work right
lda CHUNK
lsr ; Strip the bit
eor CHUNK
sta CHUNK
txa
bne @CONT ; If dy=0, it's just a point
inx
@CONT: lsr ; Init. counter to dy/2
;
; Main loop
;
YLOOP: sta TEMP
lda (POINT),y ; Plot
eor BITMASK
and CHUNK
eor (POINT),y
sta (POINT),y
YINCDEC:
iny ; Advance Y co-ordinate
lda TEMP ; Restore A
sec
sbc DX
bcc YFIXX
YCONT: dex ; X is counter
bne YLOOP
YCONT2: lda (POINT),y ; Plot endpoint
eor BITMASK
and CHUNK
eor (POINT),y
sta (POINT),y
rts
YFIXX: ; x=x+1
adc DY
lsr CHUNK
bne YCONT ; If we pass a column boundary,
ror CHUNK ; then reset CHUNK to $80
sta TEMP2
lda POINT
adc #YRES
sta POINT
bcc @CONT
inc POINT+1
@CONT: lda TEMP2
dex
bne YLOOP
beq YCONT2
;
; Big steps in X direction
;
; On entry, X=DY=number of loop iterations, and Y=Y1
.bss
COUNTHI:
.byte $00 ; Temporary counter,
; used only once
.code
STEPINX:
ldx DX
lda DX+1
sta COUNTHI
cmp #$80
ror ; Need bit for initialization
sta Y1 ; High byte of counter
txa
bne @CONT ; Could be $100
dec COUNTHI
@CONT: ror
;
; Main loop
;
XLOOP: lsr CHUNK
beq XFIXC ; If we pass a column boundary...
XCONT1: sbc DY
bcc XFIXY ; Time to step in Y?
XCONT2: dex
bne XLOOP
dec COUNTHI ; High bits set?
bpl XLOOP
lsr CHUNK ; Advance to last point
jmp LINEPLOT ; Plot the last chunk
;
; CHUNK has passed a column; so, plot and increment pointer;
; and fix up CHUNK, OLDCHUNK.
;
XFIXC: sta TEMP
jsr LINEPLOT
lda #$FF
sta CHUNK
sta OLDCHUNK
lda POINT
clc
adc #YRES
sta POINT
lda TEMP
bcc XCONT1
inc POINT+1
jmp XCONT1
;
; Check to make sure there isn't a high bit; plot chunk;
; and update Y co-ordinate.
;
XFIXY: dec Y1 ; Maybe high bit set
bpl XCONT2
adc DX
sta TEMP
lda DX+1
adc #$FF ; Hi byte
sta Y1
jsr LINEPLOT ; Plot chunk
lda CHUNK
sta OLDCHUNK
lda TEMP
XINCDEC:
iny ; Y co-ord
jmp XCONT2
;
; Subroutine to plot chunks/points (to save a little
; room, gray hair, etc.)
;
LINEPLOT: ; Plot the line chunk
lda (POINT),Y
eor BITMASK
ora CHUNK
and OLDCHUNK
eor CHUNK
eor (POINT),Y
sta (POINT),Y
rts
.endproc
; In: xpos, ypos, width, height
; ------------------------------------------------------------------------
; BAR: Draw a filled rectangle with the corners X1/Y1, X2/Y2, where
; X1/Y1 = ptr1/ptr2 and X2/Y2 = ptr3/ptr4 using the current drawing color.
; Contrary to most other functions, the graphics kernel will sort and clip
; the co-ordinates before calling the driver; so, on entry, the following
; conditions are valid:
; X1 <= X2
; Y1 <= Y2
; (X1 >= 0) && (X1 < XRES)
; (X2 >= 0) && (X2 < XRES)
; (Y1 >= 0) && (Y1 < YRES)
; (Y2 >= 0) && (Y2 < YRES)
;
; Must set an error code: NO
;
.proc BAR
; Set user pattern if available.
lda USERPATTERN
ora USERPATTERN+1
beq @GET_PATTERN_BY_COLOR
lda USERPATTERN
sta PATTERN
lda USERPATTERN+1
sta PATTERN+1
jmp @GOT_PATTERN
; Determine pattern based on current colour.
@GET_PATTERN_BY_COLOR:
lda #<PATTERN_SOLID
ldx #>PATTERN_SOLID
ldy CURCOL
bne @L2
lda #<PATTERN_EMPTY
ldx #>PATTERN_EMPTY
@L2: sta PATTERN
stx PATTERN+1
@GOT_PATTERN:
; Get starting POINT on screen.
jsr CALC
sty XCPOS
lda POINT ; One off for VFILL/VCOPY.
sec
sbc #1
sta POINT
bcs @L3
dec POINT+1
@L3:
; Get height for VFILL.
lda Y2
sec
sbc Y1
sta HEIGHT
; Get rightmost char column.
lda X2
and #7
sta XPOSR
; Get width in characters.
lda X2
lsr
lsr
lsr
sec
sbc XCPOS
beq @DRAW_SINGLE_COLUMN
sta COUNTER
; Draw left end.
lda X1
and #7
tax
lda MASKD_LEFT,x
sta MASKD
lda MASKS_LEFT,x
sta MASKS
jsr VFILL
jsr INCPOINTX
; Draw middle.
dec COUNTER
beq @DRAW_RIGHT_END
@L1: jsr VCOPY
jsr INCPOINTX
dec COUNTER
bne @L1
; Draw right end.
@DRAW_RIGHT_END:
ldx XPOSR
lda MASKD_RIGHT,x
sta MASKD
lda MASKS_RIGHT,x
sta MASKS
jmp VFILL
; Draw left end.
@DRAW_SINGLE_COLUMN:
lda X1
and #7
tax
ldy XPOSR
lda MASKS_LEFT,x
and MASKS_RIGHT,y
sta MASKS
lda MASKD_LEFT,x
ora MASKD_RIGHT,y
sta MASKD
jmp VFILL
.endproc
; In: HEIGHT, PATTERN
; MASKS: Source mask (ANDed with pattern).
; MASKD: Destination mask (ANDed with screen).
; POINT: Starting address.
; ------------------------------------------------------------------------
; Fill column with pattern using masks.
;
.proc VFILL
lda PATTERN
sta @MOD_PATTERN+1
lda PATTERN+1
sta @MOD_PATTERN+2
ldy HEIGHT
lda Y1
and #7
tax
@L1: lda (POINT),y
and MASKD
sta TMP
@MOD_PATTERN:
lda $FFFF,x
and MASKS
ora TMP
sta (POINT),y
inx
txa
and #7
tax
dey
bne @L1
rts
.endproc
; In: HEIGHT, PATTERN, POINT
; ------------------------------------------------------------------------
; Fill column with pattern.
;
.proc VCOPY
lda PATTERN
sta @MOD_PATTERN+1
lda PATTERN+1
sta @MOD_PATTERN+2
ldy HEIGHT
lda Y1
and #7
tax
@MOD_PATTERN:
@L1: lda $FFFF,x
sta (POINT),y
inx
txa
and #7
tax
dey
bne @L1
rts
.endproc
.proc INCPOINTX
lda POINT
clc
adc #YRES
sta POINT
bcc @L1
inc POINT+1
@L1: rts
.endproc
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