2 ; Graphics driver for the 640x480x2 mode on the C128 VDC 64k
3 ; (values for this mode based on Fred Bowen's document)
4 ; Maciej 'YTM/Elysium' Witkowiak <ytm@elysium.pl>
8 ; For any smart monkey that will try to optimize this: PLEASE do tests on real VDC,
11 ; Only DONE routine contains C128-mode specific stuff, everything else will work in
12 ; C64-mode of C128 (C64 needs full VDC init then).
14 ; With special initialization and CALC we can get 320x200 double-pixel mode.
16 ; Color translation values for BROWN and GRAY3 are obviously wrong, they could
17 ; be replaced by equiv. of ORANGE and GRAY2 but this would give only 14 of 16 colors available.
19 ; Register 25 ($19) is said to require different value for VDC v1, but I couldn't find what
22 .include "zeropage.inc"
24 .include "tgi-kernel.inc"
25 .include "tgi-mode.inc"
26 .include "tgi-error.inc"
31 ; ------------------------------------------------------------------------
34 VDC_ADDR_REG = $D600 ; VDC address
35 VDC_DATA_REG = $D601 ; VDC data
37 VDC_DSP_HI = 12 ; registers used
48 ; ------------------------------------------------------------------------
49 ; Header. Includes jump table and constants.
53 ; First part of the header is a structure that has a magic and defines the
54 ; capabilities of the driver
56 .byte $74, $67, $69 ; "tgi"
57 .byte $00 ; TGI version number
58 xres: .word 640 ; X resolution
59 yres: .word 480 ; Y resolution
60 .byte 2 ; Number of drawing colors
61 pages: .byte 0 ; Number of screens available
62 .byte 8 ; System font X size
63 .byte 8 ; System font Y size
64 .res 4, $00 ; Reserved for future extensions
66 ; Next comes the jump table. Currently all entries must be valid and may point
67 ; to an RTS for test versions (function not implemented). A future version may
68 ; allow for emulation: In this case the vector will be zero. Emulation means
69 ; that the graphics kernel will emulate the function by using lower level
70 ; primitives - for example ploting a line by using calls to SETPIXEL.
94 ; ------------------------------------------------------------------------
97 ; Variables mapped to the zero page segment variables. Some of these are
98 ; used for passing parameters to the driver.
106 ADDR = tmp1 ; (2) CALC
107 TEMP = tmp3 ; CALC icmp
110 TEMP4 = sreg+1 ; LINE
112 ; Line routine stuff (must be on zpage)
115 ERR = regsave ; (2) LINE
116 NX = regsave+2 ; (2) LINE
118 XX = ptr3 ; (2) CIRCLE
119 YY = ptr4 ; (2) CIRCLE
120 MaxO = sreg ; (overwritten by TEMP3+TEMP4, but restored from OG/OU anyway)
121 XS = regsave ; (2) CIRCLE
122 YS = regsave+2 ; (2) CIRCLE
124 ; Absolute variables used in the code
128 ERROR: .res 1 ; Error code
129 PALETTE: .res 2 ; The current palette
131 BITMASK: .res 1 ; $00 = clear, $FF = set pixels
133 OLDCOLOR: .res 1 ; colors before entering gfx mode
135 ; Line routine stuff (combined with CIRCLE to save space)
151 ; Constants and tables
155 DEFPALETTE: .byte $00, $0f ; White on black
156 PALETTESIZE = * - DEFPALETTE
158 BITTAB: .byte $80,$40,$20,$10,$08,$04,$02,$01
160 BITMASKL: .byte %11111111, %01111111, %00111111, %00011111
161 .byte %00001111, %00000111, %00000011, %00000001
163 BITMASKR: .byte %10000000, %11000000, %11100000, %11110000
164 .byte %11111000, %11111100, %11111110, %11111111
166 ; color translation table (indexed by VIC color)
167 COLTRANS: .byte $00, $0f, $08, $06, $0a, $04, $02, $0c
168 .byte $0d, $0b, $09, $01, $0e, $05, $03, $07
169 ; colors BROWN and GRAY3 are wrong
171 ; VDC initialization table (reg),(val),...,$ff
173 .byte VDC_DSP_HI, 0 ; viewpage 0 as default
175 .byte VDC_HSCROLL, $87
186 SCN80CLR: .byte 27,88,147,27,88,0
190 ; ------------------------------------------------------------------------
191 ; INSTALL routine. Is called after the driver is loaded into memory. May
192 ; initialize anything that has to be done just once. Is probably empty
195 ; Must set an error code: NO
199 ; check for VDC version and update register $19 value
201 ; check for VDC ram size and update number of available screens
203 ldx #VDC_CSET ; determine size of RAM...
207 jsr VDCWriteReg ; turn on 64k
209 jsr settestadr1 ; save original value of test byte
213 lda #$55 ; write $55 here
215 jsr test64k ; read it here and there
216 lda #$aa ; write $aa here
218 jsr test64k ; read it here and there
222 jsr VDCWriteByte ; restore original value of test byte
224 lda ptr1 ; do bytes match?
233 jsr VDCWriteReg ; restore 16/64k flag
234 jmp @endok ; and leave default values for 16k
249 jsr VDCWriteByte ; write $55
251 jsr VDCReadByte ; read here
254 jsr VDCReadByte ; and there
263 ldy #$02 ; test page 2 (here)
266 ldy #$42 ; or page 64+2 (there)
270 ; ------------------------------------------------------------------------
271 ; UNINSTALL routine. Is called before the driver is removed from memory. May
272 ; clean up anything done by INSTALL but is probably empty most of the time.
274 ; Must set an error code: NO
281 ; ------------------------------------------------------------------------
282 ; INIT: Changes an already installed device from text mode to graphics
284 ; Note that INIT/DONE may be called multiple times while the driver
285 ; is loaded, while INSTALL is only called once, so any code that is needed
286 ; to initializes variables and so on must go here. Setting palette and
287 ; clearing the screen is not needed because this is called by the graphics
289 ; The graphics kernel will never call INIT when a graphics mode is already
290 ; active, so there is no need to protect against that.
292 ; Must set an error code: YES
296 lda pages ; is there enough memory?
297 bne @L11 ; Jump if there is one screen
298 lda #TGI_ERR_INV_MODE ; ## Error
301 ; Initialize variables
306 ; Remeber current color value
311 ; Switch into graphics mode (set view page 0)
314 @L2: ldx InitVDCTab,y
323 ; Done, reset the error code
329 ; ------------------------------------------------------------------------
330 ; DONE: Will be called to switch the graphics device back into text mode.
331 ; The graphics kernel will never call DONE when no graphics mode is active,
332 ; so there is no need to protect against that.
334 ; Must set an error code: YES
338 ; This part is C128-mode specific
339 jsr $e179 ; reload character set and setup VDC
341 lda $d7 ; in 80-columns?
345 jsr $ffd2 ; print \xe,clr,\xe
349 jsr $ffd2 ; print clr
350 @L1: lda #0 ; restore view page
355 jsr VDCWriteReg ; restore color (background)
358 jsr VDCWriteReg ; switch to text screen
359 ; fall through to GETERROR in order to clear ERROR status
361 ; ------------------------------------------------------------------------
362 ; GETERROR: Return the error code in A and clear it.
370 ; ------------------------------------------------------------------------
371 ; CONTROL: Platform/driver specific entry point.
373 ; Must set an error code: YES
377 lda #TGI_ERR_INV_FUNC
381 ; ------------------------------------------------------------------------
382 ; CLEAR: Clears the screen.
384 ; Must set an error code: NO
393 jsr VDCWriteReg ; set fill mode
395 jsr VDCWriteByte ; put 1rst byte (fill value)
404 ; ------------------------------------------------------------------------
405 ; SETVIEWPAGE: Set the visible page. Called with the new page in A (0..n).
406 ; The page number is already checked to be valid by the graphics kernel.
408 ; Must set an error code: NO (will only be called if page ok)
414 ; ------------------------------------------------------------------------
415 ; SETDRAWPAGE: Set the drawable page. Called with the new page in A (0..n).
416 ; The page number is already checked to be valid by the graphics kernel.
418 ; Must set an error code: NO (will only be called if page ok)
424 ; ------------------------------------------------------------------------
425 ; SETCOLOR: Set the drawing color (in A). The new color is already checked
426 ; to be in a valid range (0..maxcolor-1).
428 ; Must set an error code: NO (will only be called if color ok)
438 ; ------------------------------------------------------------------------
439 ; SETPALETTE: Set the palette (not available with all drivers/hardware).
440 ; A pointer to the palette is passed in ptr1. Must set an error if palettes
443 ; Must set an error code: YES
448 @L1: lda (ptr1),y ; Copy the palette
449 and #$0F ; Make a valid color
454 ; Get the color entries from the palette
456 ldy PALETTE+1 ; Foreground color
462 ldy PALETTE ; Background color
468 ; ------------------------------------------------------------------------
469 ; GETPALETTE: Return the current palette in A/X. Must return NULL and set an
470 ; error if palettes are not supported.
472 ; Must set an error code: YES
480 ; ------------------------------------------------------------------------
481 ; GETDEFPALETTE: Return the default palette for the driver in A/X. Must
482 ; return NULL and set an error of palettes are not supported.
484 ; Must set an error code: YES
492 ; ------------------------------------------------------------------------
493 ; SETPIXEL: Draw one pixel at X1/Y1 = ptr1/ptr2 with the current drawing
494 ; color. The coordinates passed to this function are never outside the
495 ; visible screen area, so there is no need for clipping inside this function.
497 ; Must set an error code: NO
512 jsr icmp ; if (xres<x1)
513 bcs @cont ; !(xres<x1)
522 jsr icmp ; if (yres<y1)
526 jsr CALC ; Calculate coordinates
548 ; ------------------------------------------------------------------------
549 ; GETPIXEL: Read the color value of a pixel and return it in A/X. The
550 ; coordinates passed to this function are never outside the visible screen
551 ; area, so there is no need for clipping inside this function.
555 jsr CALC ; Calculate coordinates
557 stx TEMP ; preserve X
569 @L1: tya ; Get color value into A
570 ldx #$00 ; Clear high byte
573 ; ------------------------------------------------------------------------
574 ; HORLINE: Draw a horizontal line from X1/Y to X2/Y, where X1 = ptr1,
575 ; Y = ptr2 and X2 = ptr3, using the current drawing color.
577 ; This is a special line drawing entry used when the line is know to be
578 ; horizontal, for example by the BAR emulation routine. If the driver does
579 ; not have special code for horizontal lines, it may just copy Y to Y2 and
580 ; proceed with the generic line drawing code.
582 ; Note: Line coordinates will always be sorted (Y1 <= X2) and clipped.
584 ; Must set an error code: NO
592 jsr CALC ; get data for LEFT
593 lda BITMASKL,x ; remember left address and bitmask
604 jsr CALC ; get data for RIGHT
608 pla ; recall data for LEFT
611 sta X1 ; put left address into X1
614 cmp #%11111111 ; if left bit <> 0
616 sta TEMP2 ; do left byte only...
631 inc X1 ; ... and proceed
635 ; do right byte (if Y2=0 ++ADDR and skip)
637 cmp #%11111111 ; if right bit <> 7
639 inc ADDR ; right bit = 7 - the next one is the last
644 @L11: lda ADDR ; do right byte only...
659 @L2: ; do the fill in the middle
660 lda ADDR ; calculate offset in full bytes
663 beq @L3 ; if equal - there are no more bytes
666 lda X1 ; setup for the left side
669 lda BITMASK ; get color
670 jsr VDCWriteByte ; put 1st value
673 beq @L3 ; 1 byte already written
675 stx ADDR ; if there are more bytes - fill them...
678 jsr VDCWriteReg ; setup for fill
681 jsr VDCWriteReg ; ... fill them NOW!
689 ; ------------------------------------------------------------------------
690 ; LINE: Draw a line from X1/Y1 to X2/Y2, where X1/Y1 = ptr1/ptr2 and
691 ; X2/Y2 = ptr3/ptr4 using the current drawing color.
693 ; Must set an error code: NO
713 @L0137: ; if (y2>y1) {
720 jmp HORLINE ; x1/x2 are sorted, y1==y2 - do faster horizontal line draw
763 ; dx = dy = 0; ax = ay = 1 }
768 ; else { dx = dy = 1; ax = ay = 0 }
778 ; for (count=nx;count>0;--count) {
783 @L0166: lda COUNT ; count>0
788 @L0167: jsr SETPIXELCLIP
822 ; if (abs(pb)<abs(ub)) {
838 ; } else { x1 = x1 + ay
871 ; ------------------------------------------------------------------------
872 ; BAR: Draw a filled rectangle with the corners X1/Y1, X2/Y2, where
873 ; X1/Y1 = ptr1/ptr2 and X2/Y2 = ptr3/ptr4 using the current drawing color.
874 ; Contrary to most other functions, the graphics kernel will sort and clip
875 ; the coordinates before calling the driver, so on entry the following
876 ; conditions are valid:
879 ; (X1 >= 0) && (X1 < XRES)
880 ; (X2 >= 0) && (X2 < XRES)
881 ; (Y1 >= 0) && (Y1 < YRES)
882 ; (Y2 >= 0) && (Y2 < YRES)
884 ; Must set an error code: NO
903 ; ------------------------------------------------------------------------
904 ; CIRCLE: Draw a circle around the center X1/Y1 (= ptr1/ptr2) with the
905 ; radius in tmp1 and the current drawing color.
907 ; Must set an error code: NO
913 jmp SETPIXELCLIP ; Plot as a point
931 stx YS+1 ; XS/YS to remember the center
940 @L12: ; plot points in 8 slices...
955 sta Y1+1 ; (stack)=ys+y, y1=(stack)
957 jsr SETPIXELCLIP ; plot(xs+x,ys+y)
965 sta Y1+1 ; y3 = y1 = ys-y
967 jsr SETPIXELCLIP ; plot(xs+x,ys-y)
979 jsr SETPIXELCLIP ; plot (xs-x,ys+y)
984 jsr SETPIXELCLIP ; plot (xs-x,ys-y)
1000 sta Y1+1 ; (stack)=ys+x, y1=(stack)
1002 jsr SETPIXELCLIP ; plot(xs+y,ys+x)
1010 sta Y1+1 ; y3 = y1 = ys-x
1012 jsr SETPIXELCLIP ; plot(xs+y,ys-x)
1016 sta Y1 ; y1 = ys+x(stack)
1024 jsr SETPIXELCLIP ; plot (xs-y,ys+x)
1029 jsr SETPIXELCLIP ; plot (xs-y,ys-x)
1079 @L0148: ; if (abs(ou)<abs(og))
1098 @L014E: ; mo = ou; }
1110 ; ------------------------------------------------------------------------
1111 ; TEXTSTYLE: Set the style used when calling OUTTEXT. Text scaling in X and Y
1112 ; direction is passend in X/Y, the text direction is passed in A.
1114 ; Must set an error code: NO
1124 ; ------------------------------------------------------------------------
1125 ; OUTTEXT: Output text at X/Y = ptr1/ptr2 using the current color and the
1126 ; current text style. The text to output is given as a zero terminated
1127 ; string with address in ptr3.
1129 ; Must set an error code: NO
1135 ; ------------------------------------------------------------------------
1136 ; Calculate all variables to plot the pixel at X1/Y1.
1137 ;------------------------
1139 ;> ADDR - address of card
1140 ;> X - bit number (X1 & 7)
1160 sta ADDR+1 ; Y*4+Y=Y*5
1170 sta ADDR ; Y*5*16=Y*80
1183 lda ADDR+1 ; ADDR = Y*80+x/8
1191 beq @even ; even line - no offset
1198 sta ADDR+1 ; odd lines are 21360 bytes farther
1205 ; copies of some runtime routines
1225 ; compare a/y to zp,x
1226 sta TEMP ; TEMP/TEMP2 - arg2
1234 tya ; x/a - arg1 (a=high)
1265 @L0: bit VDC_ADDR_REG
1274 @L0: bit VDC_ADDR_REG