2 ; Graphics driver for the 640x200x2 mode on the C128 VDC
3 ; Maciej 'YTM/Elysium' Witkowiak <ytm@elysium.pl>
7 ; For any smart monkey that will try to optimize this: PLEASE do tests on real VDC,
10 ; Only DONE routine contains C128-mode specific stuff, everything else will work in
11 ; C64-mode of C128 (C64 needs full VDC init then).
13 ; With special initialization and CALC we can get 320x200 double-pixel mode.
15 ; Color translation values for BROWN and GRAY3 are obviously wrong, they could
16 ; be replaced by equiv. of ORANGE and GRAY2 but this would give only 14 of 16 colors available.
18 ; Register 25 ($19) is said to require different value for VDC v1, but I couldn't find what
21 .include "zeropage.inc"
23 .include "tgi-kernel.inc"
24 .include "tgi-mode.inc"
25 .include "tgi-error.inc"
30 ; ------------------------------------------------------------------------
33 VDC_ADDR_REG = $D600 ; VDC address
34 VDC_DATA_REG = $D601 ; VDC data
36 VDC_DSP_HI = 12 ; registers used
47 ; ------------------------------------------------------------------------
48 ; Header. Includes jump table and constants.
52 ; First part of the header is a structure that has a magic and defines the
53 ; capabilities of the driver
55 .byte $74, $67, $69 ; "tgi"
56 .byte $00 ; TGI version number
57 xres: .word 640 ; X resolution
58 yres: .word 200 ; Y resolution
59 .byte 2 ; Number of drawing colors
60 pages: .byte 1 ; Number of screens available
61 .byte 8 ; System font X size
62 .byte 8 ; System font Y size
63 .res 4, $00 ; Reserved for future extensions
65 ; Next comes the jump table. Currently all entries must be valid and may point
66 ; to an RTS for test versions (function not implemented). A future version may
67 ; allow for emulation: In this case the vector will be zero. Emulation means
68 ; that the graphics kernel will emulate the function by using lower level
69 ; primitives - for example ploting a line by using calls to SETPIXEL.
93 ; ------------------------------------------------------------------------
96 ; Variables mapped to the zero page segment variables. Some of these are
97 ; used for passing parameters to the driver.
105 ADDR = tmp1 ; (2) CALC
106 TEMP = tmp3 ; CALC icmp
109 TEMP4 = sreg+1 ; LINE
111 ; Line routine stuff (must be on zpage)
114 ERR = regsave ; (2) LINE
115 NX = regsave+2 ; (2) LINE
117 XX = ptr3 ; (2) CIRCLE
118 YY = ptr4 ; (2) CIRCLE
119 MaxO = sreg ; (overwritten by TEMP3+TEMP4, but restored from OG/OU anyway)
120 XS = regsave ; (2) CIRCLE
121 YS = regsave+2 ; (2) CIRCLE
123 ; Absolute variables used in the code
127 SCRBASE: .res 1 ; High byte of screen base
129 ERROR: .res 1 ; Error code
130 PALETTE: .res 2 ; The current palette
132 BITMASK: .res 1 ; $00 = clear, $FF = set pixels
134 OLDCOLOR: .res 1 ; colors before entering gfx mode
136 ; Line routine stuff (combined with CIRCLE to save space)
152 ; Constants and tables
156 DEFPALETTE: .byte $00, $0f ; White on black
157 PALETTESIZE = * - DEFPALETTE
159 BITTAB: .byte $80,$40,$20,$10,$08,$04,$02,$01
161 BITMASKL: .byte %11111111, %01111111, %00111111, %00011111
162 .byte %00001111, %00000111, %00000011, %00000001
164 BITMASKR: .byte %10000000, %11000000, %11100000, %11110000
165 .byte %11111000, %11111100, %11111110, %11111111
167 ; color translation table (indexed by VIC color)
168 COLTRANS: .byte $00, $0f, $08, $06, $0a, $04, $02, $0c
169 .byte $0d, $0b, $09, $01, $0e, $05, $03, $07
170 ; colors BROWN and GRAY3 are wrong
172 ; VDC initialization table (reg),(val),...,$ff
174 .byte VDC_DSP_HI, 0 ; viewpage 0 as default
176 .byte VDC_HSCROLL, $87
179 SCN80CLR: .byte 27,88,147,27,88,0
183 ; ------------------------------------------------------------------------
184 ; INSTALL routine. Is called after the driver is loaded into memory. May
185 ; initialize anything that has to be done just once. Is probably empty
188 ; Must set an error code: NO
192 ; check for VDC version and update register $19 value
194 ; check for VDC ram size and update number of available screens
196 ldx #VDC_CSET ; determine size of RAM...
200 jsr VDCWriteReg ; turn on 64k
202 jsr settestadr1 ; save original value of test byte
206 lda #$55 ; write $55 here
208 jsr test64k ; read it here and there
209 lda #$aa ; write $aa here
211 jsr test64k ; read it here and there
215 jsr VDCWriteByte ; restore original value of test byte
217 lda ptr1 ; do bytes match?
226 jsr VDCWriteReg ; restore 16/64k flag
227 jmp @endok ; and leave default values for 16k
234 sta SCRBASE ; draw page 0 as default
244 jsr VDCWriteByte ; write $55
246 jsr VDCReadByte ; read here
249 jsr VDCReadByte ; and there
258 ldy #$02 ; test page 2 (here)
261 ldy #$42 ; or page 64+2 (there)
265 ; ------------------------------------------------------------------------
266 ; UNINSTALL routine. Is called before the driver is removed from memory. May
267 ; clean up anything done by INSTALL but is probably empty most of the time.
269 ; Must set an error code: NO
276 ; ------------------------------------------------------------------------
277 ; INIT: Changes an already installed device from text mode to graphics
279 ; Note that INIT/DONE may be called multiple times while the driver
280 ; is loaded, while INSTALL is only called once, so any code that is needed
281 ; to initializes variables and so on must go here. Setting palette and
282 ; clearing the screen is not needed because this is called by the graphics
284 ; The graphics kernel will never call INIT when a graphics mode is already
285 ; active, so there is no need to protect against that.
287 ; Must set an error code: YES
292 ; Initialize variables
297 ; Remeber current color value
302 ; Switch into graphics mode (set view page 0)
305 @L2: ldx InitVDCTab,y
314 ; Done, reset the error code
320 ; ------------------------------------------------------------------------
321 ; DONE: Will be called to switch the graphics device back into text mode.
322 ; The graphics kernel will never call DONE when no graphics mode is active,
323 ; so there is no need to protect against that.
325 ; Must set an error code: YES
329 ; This part is C128-mode specific
330 jsr $e179 ; reload character set and setup VDC
332 lda $d7 ; in 80-columns?
336 jsr $ffd2 ; print \xe,clr,\xe
340 jsr $ffd2 ; print clr
341 @L1: lda #0 ; restore view page
346 jsr VDCWriteReg ; restore color (background)
349 jsr VDCWriteReg ; switch to text screen
350 ; fall through to GETERROR in order to clear ERROR status
352 ; ------------------------------------------------------------------------
353 ; GETERROR: Return the error code in A and clear it.
361 ; ------------------------------------------------------------------------
362 ; CONTROL: Platform/driver specific entry point.
364 ; Must set an error code: YES
368 lda #TGI_ERR_INV_FUNC
372 ; ------------------------------------------------------------------------
373 ; CLEAR: Clears the screen.
375 ; Must set an error code: NO
384 jsr VDCWriteReg ; set fill mode
386 jsr VDCWriteByte ; put 1rst byte (fill value)
394 jmp VDCWriteReg ; 1+62*256+127=16000=(640*256)/8
396 ; ------------------------------------------------------------------------
397 ; SETVIEWPAGE: Set the visible page. Called with the new page in A (0..n).
398 ; The page number is already checked to be valid by the graphics kernel.
400 ; Must set an error code: NO (will only be called if page ok)
411 ; ------------------------------------------------------------------------
412 ; SETDRAWPAGE: Set the drawable page. Called with the new page in A (0..n).
413 ; The page number is already checked to be valid by the graphics kernel.
415 ; Must set an error code: NO (will only be called if page ok)
426 ; ------------------------------------------------------------------------
427 ; SETCOLOR: Set the drawing color (in A). The new color is already checked
428 ; to be in a valid range (0..maxcolor-1).
430 ; Must set an error code: NO (will only be called if color ok)
440 ; ------------------------------------------------------------------------
441 ; SETPALETTE: Set the palette (not available with all drivers/hardware).
442 ; A pointer to the palette is passed in ptr1. Must set an error if palettes
445 ; Must set an error code: YES
450 @L1: lda (ptr1),y ; Copy the palette
451 and #$0F ; Make a valid color
456 ; Get the color entries from the palette
458 ldy PALETTE+1 ; Foreground color
464 ldy PALETTE ; Background color
470 ; ------------------------------------------------------------------------
471 ; GETPALETTE: Return the current palette in A/X. Must return NULL and set an
472 ; error if palettes are not supported.
474 ; Must set an error code: YES
482 ; ------------------------------------------------------------------------
483 ; GETDEFPALETTE: Return the default palette for the driver in A/X. Must
484 ; return NULL and set an error of palettes are not supported.
486 ; Must set an error code: YES
494 ; ------------------------------------------------------------------------
495 ; SETPIXEL: Draw one pixel at X1/Y1 = ptr1/ptr2 with the current drawing
496 ; color. The coordinates passed to this function are never outside the
497 ; visible screen area, so there is no need for clipping inside this function.
499 ; Must set an error code: NO
514 jsr icmp ; if (xres<x1)
515 bcs @cont ; !(xres<x1)
524 jsr icmp ; if (yres<y1)
528 jsr CALC ; Calculate coordinates
550 ; ------------------------------------------------------------------------
551 ; GETPIXEL: Read the color value of a pixel and return it in A/X. The
552 ; coordinates passed to this function are never outside the visible screen
553 ; area, so there is no need for clipping inside this function.
557 jsr CALC ; Calculate coordinates
559 stx TEMP ; preserve X
571 @L1: tya ; Get color value into A
572 ldx #$00 ; Clear high byte
575 ; ------------------------------------------------------------------------
576 ; HORLINE: Draw a horizontal line from X1/Y to X2/Y, where X1 = ptr1,
577 ; Y = ptr2 and X2 = ptr3, using the current drawing color.
579 ; This is a special line drawing entry used when the line is know to be
580 ; horizontal, for example by the BAR emulation routine. If the driver does
581 ; not have special code for horizontal lines, it may just copy Y to Y2 and
582 ; proceed with the generic line drawing code.
584 ; Note: Line coordinates will always be sorted (Y1 <= X2) and clipped.
586 ; Must set an error code: NO
594 jsr CALC ; get data for LEFT
595 lda BITMASKL,x ; remember left address and bitmask
606 jsr CALC ; get data for RIGHT
610 pla ; recall data for LEFT
613 sta X1 ; put left address into X1
616 cmp #%11111111 ; if left bit <> 0
618 sta TEMP2 ; do left byte only...
633 inc X1 ; ... and proceed
637 ; do right byte (if Y2=0 ++ADDR and skip)
639 cmp #%11111111 ; if right bit <> 7
641 inc ADDR ; right bit = 7 - the next one is the last
646 @L11: lda ADDR ; do right byte only...
661 @L2: ; do the fill in the middle
662 lda ADDR ; calculate offset in full bytes
665 beq @L3 ; if equal - there are no more bytes
668 lda X1 ; setup for the left side
671 lda BITMASK ; get color
672 jsr VDCWriteByte ; put 1st value
675 beq @L3 ; 1 byte already written
677 stx ADDR ; if there are more bytes - fill them...
680 jsr VDCWriteReg ; setup for fill
683 jsr VDCWriteReg ; ... fill them NOW!
691 ; ------------------------------------------------------------------------
692 ; LINE: Draw a line from X1/Y1 to X2/Y2, where X1/Y1 = ptr1/ptr2 and
693 ; X2/Y2 = ptr3/ptr4 using the current drawing color.
695 ; Must set an error code: NO
715 @L0137: ; if (y2>y1) {
722 jmp HORLINE ; x1/x2 are sorted, y1==y2 - do faster horizontal line draw
765 ; dx = dy = 0; ax = ay = 1 }
770 ; else { dx = dy = 1; ax = ay = 0 }
780 ; for (count=nx;count>0;--count) {
785 @L0166: lda COUNT ; count>0
790 @L0167: jsr SETPIXELCLIP
824 ; if (abs(pb)<abs(ub)) {
840 ; } else { x1 = x1 + ay
873 ; ------------------------------------------------------------------------
874 ; BAR: Draw a filled rectangle with the corners X1/Y1, X2/Y2, where
875 ; X1/Y1 = ptr1/ptr2 and X2/Y2 = ptr3/ptr4 using the current drawing color.
876 ; Contrary to most other functions, the graphics kernel will sort and clip
877 ; the coordinates before calling the driver, so on entry the following
878 ; conditions are valid:
881 ; (X1 >= 0) && (X1 < XRES)
882 ; (X2 >= 0) && (X2 < XRES)
883 ; (Y1 >= 0) && (Y1 < YRES)
884 ; (Y2 >= 0) && (Y2 < YRES)
886 ; Must set an error code: NO
905 ; ------------------------------------------------------------------------
906 ; CIRCLE: Draw a circle around the center X1/Y1 (= ptr1/ptr2) with the
907 ; radius in tmp1 and the current drawing color.
909 ; Must set an error code: NO
915 jmp SETPIXELCLIP ; Plot as a point
933 stx YS+1 ; XS/YS to remember the center
942 @L12: ; plot points in 8 slices...
957 sta Y1+1 ; (stack)=ys+y, y1=(stack)
959 jsr SETPIXELCLIP ; plot(xs+x,ys+y)
967 sta Y1+1 ; y3 = y1 = ys-y
969 jsr SETPIXELCLIP ; plot(xs+x,ys-y)
981 jsr SETPIXELCLIP ; plot (xs-x,ys+y)
986 jsr SETPIXELCLIP ; plot (xs-x,ys-y)
1002 sta Y1+1 ; (stack)=ys+x, y1=(stack)
1004 jsr SETPIXELCLIP ; plot(xs+y,ys+x)
1012 sta Y1+1 ; y3 = y1 = ys-x
1014 jsr SETPIXELCLIP ; plot(xs+y,ys-x)
1018 sta Y1 ; y1 = ys+x(stack)
1026 jsr SETPIXELCLIP ; plot (xs-y,ys+x)
1031 jsr SETPIXELCLIP ; plot (xs-y,ys-x)
1081 @L0148: ; if (abs(ou)<abs(og))
1100 @L014E: ; mo = ou; }
1112 ; ------------------------------------------------------------------------
1113 ; TEXTSTYLE: Set the style used when calling OUTTEXT. Text scaling in X and Y
1114 ; direction is passend in X/Y, the text direction is passed in A.
1116 ; Must set an error code: NO
1126 ; ------------------------------------------------------------------------
1127 ; OUTTEXT: Output text at X/Y = ptr1/ptr2 using the current color and the
1128 ; current text style. The text to output is given as a zero terminated
1129 ; string with address in ptr3.
1131 ; Must set an error code: NO
1137 ; ------------------------------------------------------------------------
1138 ; Calculate all variables to plot the pixel at X1/Y1.
1139 ;------------------------
1141 ;> ADDR - address of card
1142 ;> X - bit number (X1 & 7)
1156 sta ADDR+1 ; Y*4+Y=Y*5
1166 sta ADDR ; Y*5*16=Y*80
1179 lda ADDR+1 ; ADDR = Y*80+x/8
1191 ; copies of some runtime routines
1211 ; compare a/y to zp,x
1212 sta TEMP ; TEMP/TEMP2 - arg2
1220 tya ; x/a - arg1 (a=high)
1251 @L0: bit VDC_ADDR_REG
1260 @L0: bit VDC_ADDR_REG