mirror of
https://github.com/cc65/cc65.git
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1278 lines
23 KiB
ArmAsm
1278 lines
23 KiB
ArmAsm
;
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; Graphics driver for the 640x200x2 mode on the C128 VDC
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; Maciej 'YTM/Elysium' Witkowiak <ytm@elysium.pl>
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; 23.12.2002
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; 2004-04-04, Greg King
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;
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; NOTES:
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; For any smart monkey that will try to optimize this: PLEASE do tests on
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; real VDC, not only VICE.
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;
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; Only DONE routine contains C128-mode specific stuff, everything else will
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; work in C64-mode of C128 (C64 needs full VDC init then).
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;
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; With special initialization and CALC we can get 320x200 double-pixel mode.
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;
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; Color translation values for BROWN and GRAY3 are obviously wrong, they
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; could be replaced by equiv. of ORANGE and GRAY2 but this would give only
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; 14 of 16 colors available.
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;
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; Register 25 ($19) is said to require different value for VDC v1, but I
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; couldn't find what it should be.
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.include "zeropage.inc"
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.include "tgi-kernel.inc"
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.include "tgi-mode.inc"
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.include "tgi-error.inc"
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.macpack generic
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; ------------------------------------------------------------------------
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; Constants
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VDC_ADDR_REG = $D600 ; VDC address
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VDC_DATA_REG = $D601 ; VDC data
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VDC_DSP_HI = 12 ; registers used
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VDC_DSP_LO = 13
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VDC_DATA_HI = 18
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VDC_DATA_LO = 19
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VDC_VSCROLL = 24
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VDC_HSCROLL = 25
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VDC_COLORS = 26
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VDC_CSET = 28
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VDC_COUNT = 30
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VDC_DATA = 31
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; ------------------------------------------------------------------------
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; Header. Includes jump table and constants.
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.segment "JUMPTABLE"
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; First part of the header is a structure that has a magic and defines the
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; capabilities of the driver
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.byte $74, $67, $69 ; "tgi"
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.byte TGI_API_VERSION ; TGI API version number
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xres: .word 640 ; X resolution
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yres: .word 200 ; Y resolution
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.byte 2 ; Number of drawing colors
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pages: .byte 1 ; Number of screens available
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.byte 8 ; System font X size
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.byte 8 ; System font Y size
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.res 4, $00 ; Reserved for future extensions
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; Next comes the jump table. Currently all entries must be valid and may point
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; to an RTS for test versions (function not implemented).
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.addr INSTALL
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.addr UNINSTALL
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.addr INIT
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.addr DONE
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.addr GETERROR
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.addr CONTROL
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.addr CLEAR
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.addr SETVIEWPAGE
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.addr SETDRAWPAGE
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.addr SETCOLOR
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.addr SETPALETTE
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.addr GETPALETTE
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.addr GETDEFPALETTE
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.addr SETPIXEL
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.addr GETPIXEL
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.addr LINE
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.addr BAR
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.addr CIRCLE
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.addr TEXTSTYLE
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.addr OUTTEXT
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.addr 0 ; IRQ entry is unused
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; ------------------------------------------------------------------------
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; Data.
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; Variables mapped to the zero page segment variables. Some of these are
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; used for passing parameters to the driver.
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X1 = ptr1
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Y1 = ptr2
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X2 = ptr3
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Y2 = ptr4
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RADIUS = tmp1
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ADDR = tmp1 ; (2) CALC
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TEMP = tmp3 ; CALC icmp
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TEMP2 = tmp4 ; icmp
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TEMP3 = sreg ; LINE
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TEMP4 = sreg+1 ; LINE
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; Line routine stuff (must be on zpage)
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PB = ptr3 ; (2) LINE
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UB = ptr4 ; (2) LINE
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ERR = regsave ; (2) LINE
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NX = regsave+2 ; (2) LINE
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; Circle stuff
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XX = ptr3 ; (2) CIRCLE
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YY = ptr4 ; (2) CIRCLE
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MaxO = sreg ; (overwritten by TEMP3+TEMP4, but restored from OG/OU anyway)
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XS = regsave ; (2) CIRCLE
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YS = regsave+2 ; (2) CIRCLE
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; Absolute variables used in the code
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.bss
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SCRBASE: .res 1 ; High byte of screen base
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ERROR: .res 1 ; Error code
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PALETTE: .res 2 ; The current palette
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BITMASK: .res 1 ; $00 = clear, $FF = set pixels
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OLDCOLOR: .res 1 ; colors before entering gfx mode
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; Line routine stuff (combined with CIRCLE to save space)
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OGora:
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COUNT: .res 2
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OUkos:
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NY: .res 2
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Y3:
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DX: .res 1
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DY: .res 1
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AX: .res 1
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AY: .res 1
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; Text output stuff
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TEXTMAGX: .res 1
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TEXTMAGY: .res 1
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TEXTDIR: .res 1
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; Constants and tables
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.rodata
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DEFPALETTE: .byte $00, $0f ; White on black
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PALETTESIZE = * - DEFPALETTE
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BITTAB: .byte $80,$40,$20,$10,$08,$04,$02,$01
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BITMASKL: .byte %11111111, %01111111, %00111111, %00011111
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.byte %00001111, %00000111, %00000011, %00000001
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BITMASKR: .byte %10000000, %11000000, %11100000, %11110000
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.byte %11111000, %11111100, %11111110, %11111111
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; color translation table (indexed by VIC color)
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COLTRANS: .byte $00, $0f, $08, $06, $0a, $04, $02, $0c
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.byte $0d, $0b, $09, $01, $0e, $05, $03, $07
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; colors BROWN and GRAY3 are wrong
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; VDC initialization table (reg),(val),...,$ff
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InitVDCTab:
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.byte VDC_DSP_HI, 0 ; viewpage 0 as default
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.byte VDC_DSP_LO, 0
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.byte VDC_HSCROLL, $87
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.byte $ff
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SCN80CLR: .byte 27,88,147,27,88,0
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.code
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; ------------------------------------------------------------------------
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; INSTALL routine. Is called after the driver is loaded into memory. May
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; initialize anything that has to be done just once. Is probably empty
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; most of the time.
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;
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; Must set an error code: NO
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;
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INSTALL:
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; check for VDC version and update register $19 value
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; check for VDC ram size and update number of available screens
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ldx #VDC_CSET ; determine size of RAM...
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jsr VDCReadReg
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sta tmp1
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ora #%00010000
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jsr VDCWriteReg ; turn on 64k
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jsr settestadr1 ; save original value of test byte
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jsr VDCReadByte
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sta tmp2
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lda #$55 ; write $55 here
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ldy #ptr1
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jsr test64k ; read it here and there
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lda #$aa ; write $aa here
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ldy #ptr2
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jsr test64k ; read it here and there
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jsr settestadr1
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lda tmp2
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jsr VDCWriteByte ; restore original value of test byte
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lda ptr1 ; do bytes match?
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cmp ptr1+1
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bne @have64k
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lda ptr2
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cmp ptr2+1
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bne @have64k
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ldx #VDC_CSET
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lda tmp1
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jsr VDCWriteReg ; restore 16/64k flag
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jmp @endok ; and leave default values for 16k
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@have64k:
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lda #4
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sta pages
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@endok:
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lda #0
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sta SCRBASE ; draw page 0 as default
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rts
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test64k:
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sta tmp1
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sty ptr3
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lda #0
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sta ptr3+1
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jsr settestadr1
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lda tmp1
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jsr VDCWriteByte ; write $55
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jsr settestadr1
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jsr VDCReadByte ; read here
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pha
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jsr settestadr2
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jsr VDCReadByte ; and there
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ldy #1
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sta (ptr3),y
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pla
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dey
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sta (ptr3),y
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rts
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settestadr1:
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ldy #$02 ; test page 2 (here)
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.byte $2c
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settestadr2:
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ldy #$42 ; or page 64+2 (there)
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lda #0
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jmp VDCSetSourceAddr
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; ------------------------------------------------------------------------
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; UNINSTALL routine. Is called before the driver is removed from memory. May
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; clean up anything done by INSTALL but is probably empty most of the time.
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;
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; Must set an error code: NO
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;
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UNINSTALL:
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rts
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; ------------------------------------------------------------------------
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; INIT: Changes an already installed device from text mode to graphics
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; mode.
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; Note that INIT/DONE may be called multiple times while the driver
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; is loaded, while INSTALL is only called once, so any code that is needed
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; to initializes variables and so on must go here. Setting palette and
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; clearing the screen is not needed because this is called by the graphics
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; kernel later.
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; The graphics kernel will never call INIT when a graphics mode is already
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; active, so there is no need to protect against that.
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;
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; Must set an error code: YES
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;
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INIT:
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; Initialize variables
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@L1: ldx #$FF
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stx BITMASK
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; Remeber current color value
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ldx #VDC_COLORS
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jsr VDCReadReg
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sta OLDCOLOR
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; Switch into graphics mode (set view page 0)
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ldy #0
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@L2: ldx InitVDCTab,y
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bmi @L3
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iny
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lda InitVDCTab,y
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jsr VDCWriteReg
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iny
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bne @L2
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@L3:
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; Done, reset the error code
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lda #TGI_ERR_OK
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sta ERROR
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rts
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; ------------------------------------------------------------------------
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; DONE: Will be called to switch the graphics device back into text mode.
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; The graphics kernel will never call DONE when no graphics mode is active,
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; so there is no need to protect against that.
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;
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; Must set an error code: NO
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;
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DONE:
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; This part is C128-mode specific
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jsr $e179 ; reload character set and setup VDC
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jsr $ff62
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lda $d7 ; in 80-columns?
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bne @L01
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@L0: lda SCN80CLR,y
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beq @L1
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jsr $ffd2 ; print \xe,clr,\xe
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iny
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bne @L0
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@L01: lda #147
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jsr $ffd2 ; print clr
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@L1: lda #0 ; restore view page
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ldx #VDC_DSP_HI
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jsr VDCWriteReg
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lda OLDCOLOR
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ldx #VDC_COLORS
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jsr VDCWriteReg ; restore color (background)
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lda #$47
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ldx #VDC_HSCROLL
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jmp VDCWriteReg ; switch to text screen
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; ------------------------------------------------------------------------
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; GETERROR: Return the error code in A and clear it.
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GETERROR:
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ldx #TGI_ERR_OK
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lda ERROR
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stx ERROR
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rts
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; ------------------------------------------------------------------------
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; CONTROL: Platform/driver specific entry point.
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;
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; Must set an error code: YES
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;
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CONTROL:
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lda #TGI_ERR_INV_FUNC
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sta ERROR
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rts
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; ------------------------------------------------------------------------
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; CLEAR: Clears the screen.
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;
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; Must set an error code: NO
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;
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CLEAR:
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lda #0
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ldy SCRBASE
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jsr VDCSetSourceAddr
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lda #0
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ldx #VDC_VSCROLL
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jsr VDCWriteReg ; set fill mode
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lda #0
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jsr VDCWriteByte ; put 1rst byte (fill value)
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ldy #62 ; 62 times
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lda #0 ; 256 bytes
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ldx #VDC_COUNT
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@L1: jsr VDCWriteReg
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dey
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bne @L1
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lda #127
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jmp VDCWriteReg ; 1+62*256+127=16000=(640*256)/8
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; ------------------------------------------------------------------------
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; SETVIEWPAGE: Set the visible page. Called with the new page in A (0..n).
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; The page number is already checked to be valid by the graphics kernel.
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;
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; Must set an error code: NO (will only be called if page ok)
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;
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SETVIEWPAGE:
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clc
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ror
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ror
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ror
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ldx #VDC_DSP_HI
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jmp VDCWriteReg
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; ------------------------------------------------------------------------
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; SETDRAWPAGE: Set the drawable page. Called with the new page in A (0..n).
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; The page number is already checked to be valid by the graphics kernel.
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;
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; Must set an error code: NO (will only be called if page ok)
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;
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SETDRAWPAGE:
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clc
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ror
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ror
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ror
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sta SCRBASE
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rts
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; ------------------------------------------------------------------------
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; SETCOLOR: Set the drawing color (in A). The new color is already checked
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; to be in a valid range (0..maxcolor-1).
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;
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; Must set an error code: NO (will only be called if color ok)
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;
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SETCOLOR:
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tax
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beq @L1
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lda #$FF
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@L1: sta BITMASK
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rts
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; ------------------------------------------------------------------------
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; SETPALETTE: Set the palette (not available with all drivers/hardware).
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; A pointer to the palette is passed in ptr1. Must set an error if palettes
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; are not supported
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;
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; Must set an error code: YES
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;
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SETPALETTE:
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ldy #PALETTESIZE - 1
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@L1: lda (ptr1),y ; Copy the palette
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and #$0F ; Make a valid color
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sta PALETTE,y
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dey
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bpl @L1
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; Get the color entries from the palette
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ldy PALETTE+1 ; Foreground color
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lda COLTRANS,y
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asl a
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asl a
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asl a
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asl a
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ldy PALETTE ; Background color
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ora COLTRANS,y
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ldx #VDC_COLORS
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jsr VDCWriteReg ; Clear error code
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lda #TGI_ERR_OK
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sta ERROR
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rts
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; ------------------------------------------------------------------------
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; GETPALETTE: Return the current palette in A/X. Even drivers that cannot
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; set the palette should return the default palette here, so there's no
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; way for this function to fail.
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;
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; Must set an error code: NO
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;
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GETPALETTE:
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lda #<PALETTE
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ldx #>PALETTE
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rts
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; ------------------------------------------------------------------------
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; GETDEFPALETTE: Return the default palette for the driver in A/X. All
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; drivers should return something reasonable here, even drivers that don't
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; support palettes, otherwise the caller has no way to determine the colors
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; of the (not changeable) palette.
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;
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; Must set an error code: NO (all drivers must have a default palette)
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;
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GETDEFPALETTE:
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lda #<DEFPALETTE
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ldx #>DEFPALETTE
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rts
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; ------------------------------------------------------------------------
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; SETPIXEL: Draw one pixel at X1/Y1 = ptr1/ptr2 with the current drawing
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; color. The coordinates passed to this function are never outside the
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; visible screen area, so there is no need for clipping inside this function.
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;
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; Must set an error code: NO
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;
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SETPIXELCLIP:
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lda Y1+1
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bmi @finito ; y<0
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lda X1+1
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bmi @finito ; x<0
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lda X1
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ldx X1+1
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sta ADDR
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stx ADDR+1
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ldx #ADDR
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lda xres
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ldy xres+1
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jsr icmp ; ( x < xres ) ...
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bcs @finito
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lda Y1
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ldx Y1+1
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sta ADDR
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stx ADDR+1
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ldx #ADDR
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lda yres
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ldy yres+1
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jsr icmp ; ... && ( y < yres )
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bcc SETPIXEL
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@finito:rts
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SETPIXEL:
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jsr CALC ; Calculate coordinates
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stx TEMP
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lda ADDR
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ldy ADDR+1
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jsr VDCSetSourceAddr
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jsr VDCReadByte
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ldx TEMP
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sta TEMP
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eor BITMASK
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and BITTAB,X
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eor TEMP
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pha
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lda ADDR
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ldy ADDR+1
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jsr VDCSetSourceAddr
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pla
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jsr VDCWriteByte
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@L9: rts
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; ------------------------------------------------------------------------
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; GETPIXEL: Read the color value of a pixel and return it in A/X. The
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; coordinates passed to this function are never outside the visible screen
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; area, so there is no need for clipping inside this function.
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GETPIXEL:
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jsr CALC ; Calculate coordinates
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stx TEMP ; preserve X
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lda ADDR
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ldy ADDR+1
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jsr VDCSetSourceAddr
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jsr VDCReadByte
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ldx TEMP
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ldy #$00
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and BITTAB,X
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beq @L1
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iny
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@L1: tya ; Get color value into A
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ldx #$00 ; Clear high byte
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rts
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; ------------------------------------------------------------------------
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; LINE: Draw a line from X1/Y1 to X2/Y2, where X1/Y1 = ptr1/ptr2 and
|
|
; X2/Y2 = ptr3/ptr4 using the current drawing color.
|
|
;
|
|
; Must set an error code: NO
|
|
;
|
|
|
|
LINE:
|
|
; nx = abs(x2 - x1)
|
|
lda X2
|
|
sec
|
|
sbc X1
|
|
sta NX
|
|
lda X2+1
|
|
sbc X1+1
|
|
tay
|
|
lda NX
|
|
jsr abs
|
|
sta NX
|
|
sty NX+1
|
|
; ny = abs(y2 - y1)
|
|
lda Y2
|
|
sec
|
|
sbc Y1
|
|
sta NY
|
|
lda Y2+1
|
|
sbc Y1+1
|
|
tay
|
|
lda NY
|
|
jsr abs
|
|
sta NY
|
|
sty NY+1
|
|
; if (x2>=x1)
|
|
ldx #X2
|
|
lda X1
|
|
ldy X1+1
|
|
jsr icmp
|
|
bcc @L0243
|
|
; dx = 1;
|
|
lda #1
|
|
bne @L0244
|
|
; else
|
|
; dx = -1;
|
|
@L0243: lda #$ff
|
|
@L0244: sta DX
|
|
; if (y2>=y1)
|
|
ldx #Y2
|
|
lda Y1
|
|
ldy Y1+1
|
|
jsr icmp
|
|
bcc @L024A
|
|
; dy = 1;
|
|
lda #1
|
|
bne @L024B
|
|
; else
|
|
; dy = -1;
|
|
@L024A: lda #$ff
|
|
@L024B: sta DY
|
|
; err = ax = ay = 0;
|
|
lda #0
|
|
sta ERR
|
|
sta ERR+1
|
|
sta AX
|
|
sta AY
|
|
|
|
; if (nx<ny) {
|
|
ldx #NX
|
|
lda NY
|
|
ldy NY+1
|
|
jsr icmp
|
|
bcs @L0255
|
|
; nx <-> ny
|
|
lda NX
|
|
ldx NY
|
|
sta NY
|
|
stx NX
|
|
lda NX+1
|
|
ldx NY+1
|
|
sta NY+1
|
|
stx NX+1
|
|
; ax = dx
|
|
lda DX
|
|
sta AX
|
|
; ay = dy
|
|
lda DY
|
|
sta AY
|
|
; dx = dy = 0;
|
|
lda #0
|
|
sta DX
|
|
sta DY
|
|
; ny = - ny;
|
|
@L0255: lda NY
|
|
ldy NY+1
|
|
jsr neg
|
|
sta NY
|
|
sty NY+1
|
|
; for (count=nx;count>0;--count) {
|
|
lda NX
|
|
ldx NX+1
|
|
sta COUNT
|
|
stx COUNT+1
|
|
@L0166: lda COUNT ; count>0
|
|
ora COUNT+1
|
|
bne @L0167
|
|
rts
|
|
; setpixel(X1,Y1)
|
|
@L0167: jsr SETPIXELCLIP
|
|
; pb = err + ny
|
|
lda ERR
|
|
clc
|
|
adc NY
|
|
sta PB
|
|
lda ERR+1
|
|
adc NY+1
|
|
sta PB+1
|
|
tax
|
|
; ub = pb + nx
|
|
lda PB
|
|
clc
|
|
adc NX
|
|
sta UB
|
|
txa
|
|
adc NX+1
|
|
sta UB+1
|
|
; x1 = x1 + dx
|
|
ldx #0
|
|
lda DX
|
|
bpl @L027B
|
|
dex
|
|
@L027B: clc
|
|
adc X1
|
|
sta X1
|
|
txa
|
|
adc X1+1
|
|
sta X1+1
|
|
; y1 = y1 + ay
|
|
ldx #0
|
|
lda AY
|
|
bpl @L027E
|
|
dex
|
|
@L027E: clc
|
|
adc Y1
|
|
sta Y1
|
|
txa
|
|
adc Y1+1
|
|
sta Y1+1
|
|
; if (abs(pb)<abs(ub)) {
|
|
lda PB
|
|
ldy PB+1
|
|
jsr abs
|
|
sta TEMP3
|
|
sty TEMP4
|
|
lda UB
|
|
ldy UB+1
|
|
jsr abs
|
|
ldx #TEMP3
|
|
jsr icmp
|
|
bpl @L027F
|
|
; err = pb
|
|
lda PB
|
|
ldx PB+1
|
|
jmp @L0312
|
|
; } else { x1 = x1 + ax
|
|
@L027F:
|
|
ldx #0
|
|
lda AX
|
|
bpl @L0288
|
|
dex
|
|
@L0288: clc
|
|
adc X1
|
|
sta X1
|
|
txa
|
|
adc X1+1
|
|
sta X1+1
|
|
; y1 = y1 + dy
|
|
ldx #0
|
|
lda DY
|
|
bpl @L028B
|
|
dex
|
|
@L028B: clc
|
|
adc Y1
|
|
sta Y1
|
|
txa
|
|
adc Y1+1
|
|
sta Y1+1
|
|
; err = ub }
|
|
lda UB
|
|
ldx UB+1
|
|
@L0312:
|
|
sta ERR
|
|
stx ERR+1
|
|
; } (--count)
|
|
sec
|
|
lda COUNT
|
|
sbc #1
|
|
sta COUNT
|
|
bcc @L0260
|
|
jmp @L0166
|
|
@L0260: dec COUNT+1
|
|
jmp @L0166
|
|
|
|
; ------------------------------------------------------------------------
|
|
; 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 coordinates 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
|
|
;
|
|
|
|
BAR:
|
|
inc Y2
|
|
bne HORLINE
|
|
inc Y2+1
|
|
|
|
; Original code for a horizontal line
|
|
|
|
HORLINE:
|
|
lda X1
|
|
pha
|
|
lda X1+1
|
|
pha
|
|
jsr CALC ; get data for LEFT
|
|
lda BITMASKL,x ; remember left address and bitmask
|
|
pha
|
|
lda ADDR
|
|
pha
|
|
lda ADDR+1
|
|
pha
|
|
|
|
lda X2
|
|
sta X1
|
|
lda X2+1
|
|
sta X1+1
|
|
jsr CALC ; get data for RIGHT
|
|
lda BITMASKR,x
|
|
sta TEMP3
|
|
|
|
pla ; recall data for LEFT
|
|
sta X1+1
|
|
pla
|
|
sta X1 ; put left address into X1
|
|
pla
|
|
|
|
cmp #%11111111 ; if left bit <> 0
|
|
beq @L1
|
|
sta TEMP2 ; do left byte only...
|
|
lda X1
|
|
ldy X1+1
|
|
jsr VDCSetSourceAddr
|
|
jsr VDCReadByte
|
|
sta TEMP
|
|
eor BITMASK
|
|
and TEMP2
|
|
eor TEMP
|
|
pha
|
|
lda X1
|
|
ldy X1+1
|
|
jsr VDCSetSourceAddr
|
|
pla
|
|
jsr VDCWriteByte
|
|
inc X1 ; ... and proceed
|
|
bne @L1
|
|
inc X1+1
|
|
|
|
; do right byte (if Y2=0 ++ADDR and skip)
|
|
@L1: lda TEMP3
|
|
cmp #%11111111 ; if right bit <> 7
|
|
bne @L11
|
|
inc ADDR ; right bit = 7 - the next one is the last
|
|
bne @L10
|
|
inc ADDR+1
|
|
@L10: bne @L2
|
|
|
|
@L11: lda ADDR ; do right byte only...
|
|
ldy ADDR+1
|
|
jsr VDCSetSourceAddr
|
|
jsr VDCReadByte
|
|
sta TEMP
|
|
eor BITMASK
|
|
and TEMP3
|
|
eor TEMP
|
|
pha
|
|
lda ADDR
|
|
ldy ADDR+1
|
|
jsr VDCSetSourceAddr
|
|
pla
|
|
jsr VDCWriteByte
|
|
|
|
@L2: ; do the fill in the middle
|
|
lda ADDR ; calculate offset in full bytes
|
|
sec
|
|
sbc X1
|
|
beq @L3 ; if equal - there are no more bytes
|
|
sta ADDR
|
|
|
|
lda X1 ; setup for the left side
|
|
ldy X1+1
|
|
jsr VDCSetSourceAddr
|
|
lda BITMASK ; get color
|
|
jsr VDCWriteByte ; put 1st value
|
|
ldx ADDR
|
|
dex
|
|
beq @L3 ; 1 byte already written
|
|
|
|
stx ADDR ; if there are more bytes - fill them...
|
|
ldx #VDC_VSCROLL
|
|
lda #0
|
|
jsr VDCWriteReg ; setup for fill
|
|
ldx #VDC_COUNT
|
|
lda ADDR
|
|
jsr VDCWriteReg ; ... fill them NOW!
|
|
|
|
@L3: pla
|
|
sta X1+1
|
|
pla
|
|
sta X1
|
|
|
|
; End of horizontal line code
|
|
|
|
inc Y1
|
|
bne @L4
|
|
inc Y1+1
|
|
@L4: lda Y1
|
|
cmp Y2
|
|
bne @L5
|
|
lda Y1+1
|
|
cmp Y2+1
|
|
bne @L5
|
|
rts
|
|
|
|
@L5: jmp HORLINE
|
|
|
|
; ------------------------------------------------------------------------
|
|
; CIRCLE: Draw a circle around the center X1/Y1 (= ptr1/ptr2) with the
|
|
; radius in tmp1 and the current drawing color.
|
|
;
|
|
; Must set an error code: NO
|
|
;
|
|
|
|
CIRCLE:
|
|
lda RADIUS
|
|
bne @L1
|
|
jmp SETPIXELCLIP ; Plot as a point
|
|
|
|
@L1: sta XX
|
|
; x = r;
|
|
lda #0
|
|
sta XX+1
|
|
sta YY
|
|
sta YY+1
|
|
sta MaxO
|
|
sta MaxO+1
|
|
; y =0; mo=0;
|
|
lda X1
|
|
ldx X1+1
|
|
sta XS
|
|
stx XS+1
|
|
lda Y1
|
|
ldx Y1+1
|
|
sta YS
|
|
stx YS+1 ; XS/YS to remember the center
|
|
|
|
; while (y<x) {
|
|
@L013B: ldx #YY
|
|
lda XX
|
|
ldy XX+1
|
|
jsr icmp
|
|
bcc @L12
|
|
rts
|
|
@L12: ; plot points in 8 slices...
|
|
lda XS
|
|
clc
|
|
adc XX
|
|
sta X1
|
|
lda XS+1
|
|
adc XX+1
|
|
sta X1+1 ; x1 = xs+x
|
|
lda YS
|
|
clc
|
|
adc YY
|
|
sta Y1
|
|
pha
|
|
lda YS+1
|
|
adc YY+1
|
|
sta Y1+1 ; (stack)=ys+y, y1=(stack)
|
|
pha
|
|
jsr SETPIXELCLIP ; plot(xs+x,ys+y)
|
|
lda YS
|
|
sec
|
|
sbc YY
|
|
sta Y1
|
|
sta Y3
|
|
lda YS+1
|
|
sbc YY+1
|
|
sta Y1+1 ; y3 = y1 = ys-y
|
|
sta Y3+1
|
|
jsr SETPIXELCLIP ; plot(xs+x,ys-y)
|
|
pla
|
|
sta Y1+1
|
|
pla
|
|
sta Y1 ; y1 = ys+y
|
|
lda XS
|
|
sec
|
|
sbc XX
|
|
sta X1
|
|
lda XS+1
|
|
sbc XX+1
|
|
sta X1+1
|
|
jsr SETPIXELCLIP ; plot (xs-x,ys+y)
|
|
lda Y3
|
|
sta Y1
|
|
lda Y3+1
|
|
sta Y1+1
|
|
jsr SETPIXELCLIP ; plot (xs-x,ys-y)
|
|
|
|
lda XS
|
|
clc
|
|
adc YY
|
|
sta X1
|
|
lda XS+1
|
|
adc YY+1
|
|
sta X1+1 ; x1 = xs+y
|
|
lda YS
|
|
clc
|
|
adc XX
|
|
sta Y1
|
|
pha
|
|
lda YS+1
|
|
adc XX+1
|
|
sta Y1+1 ; (stack)=ys+x, y1=(stack)
|
|
pha
|
|
jsr SETPIXELCLIP ; plot(xs+y,ys+x)
|
|
lda YS
|
|
sec
|
|
sbc XX
|
|
sta Y1
|
|
sta Y3
|
|
lda YS+1
|
|
sbc XX+1
|
|
sta Y1+1 ; y3 = y1 = ys-x
|
|
sta Y3+1
|
|
jsr SETPIXELCLIP ; plot(xs+y,ys-x)
|
|
pla
|
|
sta Y1+1
|
|
pla
|
|
sta Y1 ; y1 = ys+x(stack)
|
|
lda XS
|
|
sec
|
|
sbc YY
|
|
sta X1
|
|
lda XS+1
|
|
sbc YY+1
|
|
sta X1+1
|
|
jsr SETPIXELCLIP ; plot (xs-y,ys+x)
|
|
lda Y3
|
|
sta Y1
|
|
lda Y3+1
|
|
sta Y1+1
|
|
jsr SETPIXELCLIP ; plot (xs-y,ys-x)
|
|
|
|
; og = mo+y+y+1
|
|
lda MaxO
|
|
ldx MaxO+1
|
|
clc
|
|
adc YY
|
|
tay
|
|
txa
|
|
adc YY+1
|
|
tax
|
|
tya
|
|
clc
|
|
adc YY
|
|
tay
|
|
txa
|
|
adc YY+1
|
|
tax
|
|
tya
|
|
clc
|
|
adc #1
|
|
bcc @L0143
|
|
inx
|
|
@L0143: sta OGora
|
|
stx OGora+1
|
|
; ou = og-x-x+1
|
|
sec
|
|
sbc XX
|
|
tay
|
|
txa
|
|
sbc XX+1
|
|
tax
|
|
tya
|
|
sec
|
|
sbc XX
|
|
tay
|
|
txa
|
|
sbc XX+1
|
|
tax
|
|
tya
|
|
clc
|
|
adc #1
|
|
bcc @L0146
|
|
inx
|
|
@L0146: sta OUkos
|
|
stx OUkos+1
|
|
; ++y
|
|
inc YY
|
|
bne @L0148
|
|
inc YY+1
|
|
@L0148: ; if (abs(ou)<abs(og))
|
|
lda OUkos
|
|
ldy OUkos+1
|
|
jsr abs
|
|
sta TEMP3
|
|
sty TEMP4
|
|
lda OGora
|
|
ldy OGora+1
|
|
jsr abs
|
|
ldx #TEMP3
|
|
jsr icmp
|
|
bpl @L0149
|
|
; { --x;
|
|
sec
|
|
lda XX
|
|
sbc #1
|
|
sta XX
|
|
bcs @L014E
|
|
dec XX+1
|
|
@L014E: ; mo = ou; }
|
|
lda OUkos
|
|
ldx OUkos+1
|
|
jmp @L014G
|
|
; else { mo = og }
|
|
@L0149: lda OGora
|
|
ldx OGora+1
|
|
@L014G: sta MaxO
|
|
stx MaxO+1
|
|
; }
|
|
jmp @L013B
|
|
|
|
; ------------------------------------------------------------------------
|
|
; TEXTSTYLE: Set the style used when calling OUTTEXT. Text scaling in X and Y
|
|
; direction is passend in X/Y, the text direction is passed in A.
|
|
;
|
|
; Must set an error code: NO
|
|
;
|
|
|
|
TEXTSTYLE:
|
|
stx TEXTMAGX
|
|
sty TEXTMAGY
|
|
sta TEXTDIR
|
|
rts
|
|
|
|
|
|
; ------------------------------------------------------------------------
|
|
; 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
|
|
;
|
|
|
|
OUTTEXT:
|
|
rts
|
|
|
|
; ------------------------------------------------------------------------
|
|
; Calculate all variables to plot the pixel at X1/Y1.
|
|
;------------------------
|
|
;< X1,Y1 - pixel
|
|
;> ADDR - address of card
|
|
;> X - bit number (X1 & 7)
|
|
CALC:
|
|
lda Y1+1
|
|
sta ADDR+1
|
|
lda Y1
|
|
asl
|
|
rol ADDR+1
|
|
asl
|
|
rol ADDR+1 ; Y*4
|
|
clc
|
|
adc Y1
|
|
sta ADDR
|
|
lda Y1+1
|
|
adc ADDR+1
|
|
sta ADDR+1 ; Y*4+Y=Y*5
|
|
lda ADDR
|
|
asl
|
|
rol ADDR+1
|
|
asl
|
|
rol ADDR+1
|
|
asl
|
|
rol ADDR+1
|
|
asl
|
|
rol ADDR+1
|
|
sta ADDR ; Y*5*16=Y*80
|
|
lda X1+1
|
|
sta TEMP
|
|
lda X1
|
|
lsr TEMP
|
|
ror
|
|
lsr TEMP
|
|
ror
|
|
lsr TEMP
|
|
ror
|
|
clc
|
|
adc ADDR
|
|
sta ADDR
|
|
lda ADDR+1 ; ADDR = Y*80+x/8
|
|
adc TEMP
|
|
sta ADDR+1
|
|
lda ADDR+1
|
|
adc SCRBASE
|
|
sta ADDR+1
|
|
lda X1
|
|
and #7
|
|
tax
|
|
rts
|
|
|
|
;-------------
|
|
; copies of some runtime routines
|
|
|
|
abs:
|
|
; a/y := abs(a/y)
|
|
cpy #$00
|
|
bpl absend
|
|
; negay
|
|
neg: eor #$ff
|
|
add #1
|
|
pha
|
|
tya
|
|
eor #$ff
|
|
adc #0
|
|
tay
|
|
pla
|
|
absend: rts
|
|
|
|
icmp:
|
|
; compare a/y to zp,x
|
|
sta TEMP ; TEMP/TEMP2 - arg2
|
|
sty TEMP2
|
|
lda $0,x
|
|
pha
|
|
lda $1,x
|
|
tay
|
|
pla
|
|
tax
|
|
tya ; x/a - arg1 (a=high)
|
|
|
|
sec
|
|
sbc TEMP2
|
|
bne @L4
|
|
cpx TEMP
|
|
beq @L3
|
|
adc #$ff
|
|
ora #$01
|
|
@L3: rts
|
|
@L4: bvc @L3
|
|
eor #$ff
|
|
ora #$01
|
|
rts
|
|
|
|
;-------------
|
|
; VDC helpers
|
|
|
|
VDCSetSourceAddr:
|
|
pha
|
|
tya
|
|
ldx #VDC_DATA_HI
|
|
jsr VDCWriteReg
|
|
pla
|
|
ldx #VDC_DATA_LO
|
|
bne VDCWriteReg
|
|
|
|
VDCReadByte:
|
|
ldx #VDC_DATA
|
|
VDCReadReg:
|
|
stx VDC_ADDR_REG
|
|
@L0: bit VDC_ADDR_REG
|
|
bpl @L0
|
|
lda VDC_DATA_REG
|
|
rts
|
|
|
|
VDCWriteByte:
|
|
ldx #VDC_DATA
|
|
VDCWriteReg:
|
|
stx VDC_ADDR_REG
|
|
@L0: bit VDC_ADDR_REG
|
|
bpl @L0
|
|
sta VDC_DATA_REG
|
|
rts
|
|
|