2 ; Graphics driver for the 640x200x2 mode on the C128 VDC
3 ; Maciej 'YTM/Elysium' Witkowiak <ytm@elysium.pl>
5 ; 2004-04-04, Greg King
8 ; For any smart monkey that will try to optimize this: PLEASE do tests on
9 ; real VDC, not only VICE.
11 ; Only DONE routine contains C128-mode specific stuff, everything else will
12 ; work in 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
17 ; could be replaced by equiv. of ORANGE and GRAY2 but this would give only
18 ; 14 of 16 colors available.
20 ; Register 25 ($19) is said to require different value for VDC v1, but I
21 ; couldn't find what it should be.
23 .include "zeropage.inc"
25 .include "tgi-kernel.inc"
26 .include "tgi-mode.inc"
27 .include "tgi-error.inc"
32 ; ------------------------------------------------------------------------
35 VDC_ADDR_REG = $D600 ; VDC address
36 VDC_DATA_REG = $D601 ; VDC data
38 VDC_DSP_HI = 12 ; registers used
49 ; ------------------------------------------------------------------------
50 ; Header. Includes jump table and constants.
54 ; First part of the header is a structure that has a magic and defines the
55 ; capabilities of the driver
57 .byte $74, $67, $69 ; "tgi"
58 .byte TGI_API_VERSION ; TGI API version number
59 xres: .word 640 ; X resolution
60 yres: .word 200 ; Y resolution
61 .byte 2 ; Number of drawing colors
62 pages: .byte 1 ; Number of screens available
63 .byte 8 ; System font X size
64 .byte 8 ; System font Y size
65 .word $100 ; Aspect ratio
67 ; Next comes the jump table. Currently all entries must be valid and may point
68 ; to an RTS for test versions (function not implemented).
89 .addr 0 ; IRQ entry is unused
91 ; ------------------------------------------------------------------------
94 ; Variables mapped to the zero page segment variables. Some of these are
95 ; used for passing parameters to the driver.
102 ADDR = tmp1 ; (2) CALC
103 TEMP = tmp3 ; CALC icmp
106 TEMP4 = sreg+1 ; LINE
108 ; Line routine stuff (must be on zpage)
111 ERR = regsave ; (2) LINE
112 NX = regsave+2 ; (2) LINE
114 ; Absolute variables used in the code
118 SCRBASE: .res 1 ; High byte of screen base
120 ERROR: .res 1 ; Error code
121 PALETTE: .res 2 ; The current palette
123 BITMASK: .res 1 ; $00 = clear, $FF = set pixels
125 OLDCOLOR: .res 1 ; colors before entering gfx mode
141 ; Constants and tables
145 DEFPALETTE: .byte $00, $0f ; White on black
146 PALETTESIZE = * - DEFPALETTE
148 BITTAB: .byte $80,$40,$20,$10,$08,$04,$02,$01
150 BITMASKL: .byte %11111111, %01111111, %00111111, %00011111
151 .byte %00001111, %00000111, %00000011, %00000001
153 BITMASKR: .byte %10000000, %11000000, %11100000, %11110000
154 .byte %11111000, %11111100, %11111110, %11111111
156 ; color translation table (indexed by VIC color)
157 COLTRANS: .byte $00, $0f, $08, $06, $0a, $04, $02, $0c
158 .byte $0d, $0b, $09, $01, $0e, $05, $03, $07
159 ; colors BROWN and GRAY3 are wrong
161 ; VDC initialization table (reg),(val),...,$ff
163 .byte VDC_DSP_HI, 0 ; viewpage 0 as default
165 .byte VDC_HSCROLL, $87
168 SCN80CLR: .byte 27,88,147,27,88,0
172 ; ------------------------------------------------------------------------
173 ; INSTALL routine. Is called after the driver is loaded into memory. May
174 ; initialize anything that has to be done just once. Is probably empty
177 ; Must set an error code: NO
181 ; check for VDC version and update register $19 value
183 ; check for VDC ram size and update number of available screens
185 ldx #VDC_CSET ; determine size of RAM...
189 jsr VDCWriteReg ; turn on 64k
191 jsr settestadr1 ; save original value of test byte
195 lda #$55 ; write $55 here
197 jsr test64k ; read it here and there
198 lda #$aa ; write $aa here
200 jsr test64k ; read it here and there
204 jsr VDCWriteByte ; restore original value of test byte
206 lda ptr1 ; do bytes match?
215 jsr VDCWriteReg ; restore 16/64k flag
216 jmp @endok ; and leave default values for 16k
223 sta SCRBASE ; draw page 0 as default
233 jsr VDCWriteByte ; write $55
235 jsr VDCReadByte ; read here
238 jsr VDCReadByte ; and there
247 ldy #$02 ; test page 2 (here)
250 ldy #$42 ; or page 64+2 (there)
254 ; ------------------------------------------------------------------------
255 ; UNINSTALL routine. Is called before the driver is removed from memory. May
256 ; clean up anything done by INSTALL but is probably empty most of the time.
258 ; Must set an error code: NO
265 ; ------------------------------------------------------------------------
266 ; INIT: Changes an already installed device from text mode to graphics
268 ; Note that INIT/DONE may be called multiple times while the driver
269 ; is loaded, while INSTALL is only called once, so any code that is needed
270 ; to initializes variables and so on must go here. Setting palette and
271 ; clearing the screen is not needed because this is called by the graphics
273 ; The graphics kernel will never call INIT when a graphics mode is already
274 ; active, so there is no need to protect against that.
276 ; Must set an error code: YES
281 ; Initialize variables
286 ; Remeber current color value
291 ; Switch into graphics mode (set view page 0)
294 @L2: ldx InitVDCTab,y
303 ; Done, reset the error code
309 ; ------------------------------------------------------------------------
310 ; DONE: Will be called to switch the graphics device back into text mode.
311 ; The graphics kernel will never call DONE when no graphics mode is active,
312 ; so there is no need to protect against that.
314 ; Must set an error code: NO
318 ; This part is C128-mode specific
319 jsr $e179 ; reload character set and setup VDC
321 lda $d7 ; in 80-columns?
325 jsr $ffd2 ; print \xe,clr,\xe
329 jsr $ffd2 ; print clr
330 @L1: lda #0 ; restore view page
335 jsr VDCWriteReg ; restore color (background)
338 jmp VDCWriteReg ; switch to text screen
340 ; ------------------------------------------------------------------------
341 ; GETERROR: Return the error code in A and clear it.
349 ; ------------------------------------------------------------------------
350 ; CONTROL: Platform/driver specific entry point.
352 ; Must set an error code: YES
356 lda #TGI_ERR_INV_FUNC
360 ; ------------------------------------------------------------------------
361 ; CLEAR: Clears the screen.
363 ; Must set an error code: NO
372 jsr VDCWriteReg ; set fill mode
374 jsr VDCWriteByte ; put 1rst byte (fill value)
382 jmp VDCWriteReg ; 1+62*256+127=16000=(640*256)/8
384 ; ------------------------------------------------------------------------
385 ; SETVIEWPAGE: Set the visible page. Called with the new page in A (0..n).
386 ; The page number is already checked to be valid by the graphics kernel.
388 ; Must set an error code: NO (will only be called if page ok)
399 ; ------------------------------------------------------------------------
400 ; SETDRAWPAGE: Set the drawable page. Called with the new page in A (0..n).
401 ; The page number is already checked to be valid by the graphics kernel.
403 ; Must set an error code: NO (will only be called if page ok)
414 ; ------------------------------------------------------------------------
415 ; SETCOLOR: Set the drawing color (in A). The new color is already checked
416 ; to be in a valid range (0..maxcolor-1).
418 ; Must set an error code: NO (will only be called if color ok)
428 ; ------------------------------------------------------------------------
429 ; SETPALETTE: Set the palette (not available with all drivers/hardware).
430 ; A pointer to the palette is passed in ptr1. Must set an error if palettes
433 ; Must set an error code: YES
438 @L1: lda (ptr1),y ; Copy the palette
439 and #$0F ; Make a valid color
444 ; Get the color entries from the palette
446 ldy PALETTE+1 ; Foreground color
452 ldy PALETTE ; Background color
456 jsr VDCWriteReg ; Clear error code
461 ; ------------------------------------------------------------------------
462 ; GETPALETTE: Return the current palette in A/X. Even drivers that cannot
463 ; set the palette should return the default palette here, so there's no
464 ; way for this function to fail.
466 ; Must set an error code: NO
474 ; ------------------------------------------------------------------------
475 ; GETDEFPALETTE: Return the default palette for the driver in A/X. All
476 ; drivers should return something reasonable here, even drivers that don't
477 ; support palettes, otherwise the caller has no way to determine the colors
478 ; of the (not changeable) palette.
480 ; Must set an error code: NO (all drivers must have a default palette)
488 ; ------------------------------------------------------------------------
489 ; SETPIXEL: Draw one pixel at X1/Y1 = ptr1/ptr2 with the current drawing
490 ; color. The coordinates passed to this function are never outside the
491 ; visible screen area, so there is no need for clipping inside this function.
493 ; Must set an error code: NO
497 jsr CALC ; Calculate coordinates
519 ; ------------------------------------------------------------------------
520 ; GETPIXEL: Read the color value of a pixel and return it in A/X. The
521 ; coordinates passed to this function are never outside the visible screen
522 ; area, so there is no need for clipping inside this function.
526 jsr CALC ; Calculate coordinates
528 stx TEMP ; preserve X
540 @L1: tya ; Get color value into A
541 ldx #$00 ; Clear high byte
544 ; ------------------------------------------------------------------------
545 ; LINE: Draw a line from X1/Y1 to X2/Y2, where X1/Y1 = ptr1/ptr2 and
546 ; X2/Y2 = ptr3/ptr4 using the current drawing color.
548 ; Must set an error code: NO
640 ; for (count=nx;count>0;--count) {
645 @L0166: lda COUNT ; count>0
690 ; if (abs(pb)<abs(ub)) {
706 ; } else { x1 = x1 + ax
745 ; ------------------------------------------------------------------------
746 ; BAR: Draw a filled rectangle with the corners X1/Y1, X2/Y2, where
747 ; X1/Y1 = ptr1/ptr2 and X2/Y2 = ptr3/ptr4 using the current drawing color.
748 ; Contrary to most other functions, the graphics kernel will sort and clip
749 ; the coordinates before calling the driver, so on entry the following
750 ; conditions are valid:
753 ; (X1 >= 0) && (X1 < XRES)
754 ; (X2 >= 0) && (X2 < XRES)
755 ; (Y1 >= 0) && (Y1 < YRES)
756 ; (Y2 >= 0) && (Y2 < YRES)
758 ; Must set an error code: NO
766 ; Original code for a horizontal line
773 jsr CALC ; get data for LEFT
774 lda BITMASKL,x ; remember left address and bitmask
785 jsr CALC ; get data for RIGHT
789 pla ; recall data for LEFT
792 sta X1 ; put left address into X1
795 cmp #%11111111 ; if left bit <> 0
797 sta TEMP2 ; do left byte only...
812 inc X1 ; ... and proceed
816 ; do right byte (if Y2=0 ++ADDR and skip)
818 cmp #%11111111 ; if right bit <> 7
820 inc ADDR ; right bit = 7 - the next one is the last
825 @L11: lda ADDR ; do right byte only...
840 @L2: ; do the fill in the middle
841 lda ADDR ; calculate offset in full bytes
844 beq @L3 ; if equal - there are no more bytes
847 lda X1 ; setup for the left side
850 lda BITMASK ; get color
851 jsr VDCWriteByte ; put 1st value
854 beq @L3 ; 1 byte already written
856 stx ADDR ; if there are more bytes - fill them...
859 jsr VDCWriteReg ; setup for fill
862 jsr VDCWriteReg ; ... fill them NOW!
869 ; End of horizontal line code
884 ; ------------------------------------------------------------------------
885 ; TEXTSTYLE: Set the style used when calling OUTTEXT. Text scaling in X and Y
886 ; direction is passend in X/Y, the text direction is passed in A.
888 ; Must set an error code: NO
898 ; ------------------------------------------------------------------------
899 ; OUTTEXT: Output text at X/Y = ptr1/ptr2 using the current color and the
900 ; current text style. The text to output is given as a zero terminated
901 ; string with address in ptr3.
903 ; Must set an error code: NO
909 ; ------------------------------------------------------------------------
910 ; Calculate all variables to plot the pixel at X1/Y1.
911 ;------------------------
913 ;> ADDR - address of card
914 ;> X - bit number (X1 & 7)
928 sta ADDR+1 ; Y*4+Y=Y*5
938 sta ADDR ; Y*5*16=Y*80
951 lda ADDR+1 ; ADDR = Y*80+x/8
963 ; copies of some runtime routines
981 ; compare a/y to zp,x
982 sta TEMP ; TEMP/TEMP2 - arg2
990 tya ; x/a - arg1 (a=high)
1021 @L0: bit VDC_ADDR_REG
1030 @L0: bit VDC_ADDR_REG