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636 lines
16 KiB
ArmAsm
636 lines
16 KiB
ArmAsm
;
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; Graphics driver for the 640 pixels across, 480 pixels down, 2 color mode
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; on the Commander X16
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;
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; 2024-06-11, Scott Hutter
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; Based on code by Greg King
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;
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.include "zeropage.inc"
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.include "tgi-kernel.inc"
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.include "tgi-error.inc"
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.include "cbm_kernal.inc"
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.include "cx16.inc"
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.macpack generic
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.macpack module
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; ------------------------------------------------------------------------
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; Header. Includes jump table and constants.
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module_header _cx640p1_tgi ; 640 pixels across, 1 pixel per bit
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; First part of the header is a structure that has a signature,
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; and defines the capabilities of the driver.
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.byte $74, $67, $69 ; ASCII "tgi"
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.byte TGI_API_VERSION ; TGI API version number
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.addr $0000 ; Library reference
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.word 640 ; X resolution
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.word 480 ; Y resolution
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.byte 2 ; Number of drawing colors
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.byte 0 ; 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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.word $0100 ; Aspect ratio (based on VGA display)
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.byte 0 ; TGI driver flags
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; Next, comes the jump table. Currently, all entries must be valid,
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; and may point 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 TEXTSTYLE
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.addr OUTTEXT
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; ------------------------------------------------------------------------
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; Constant
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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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ADDR = tmp1 ; ADDR+1,2,3
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TEMP = tmp3
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TEMP2 = tmp4 ; HORLINE
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TEMP3 = sreg ; HORLINE
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tempX:
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.byte $00, $00
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tempY:
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.byte $00, $00
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ERR2:
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.byte $00
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ERR:
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.byte $00
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SY:
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.byte $00
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SX:
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.byte $00
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DY:
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.byte $00
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DX:
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.byte $00
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CURRENT_Y:
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.byte $00, $00
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CURRENT_X:
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.byte $00, $00
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; Absolute variables used in the code
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.bss
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; The colors are indicies into a TGI palette. The TGI palette is indicies into
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; VERA's palette. Vera's palette is a table of Red, Green, and Blue levels.
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; The first 16 RGB elements mimic the Commodore 64's colors.
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SCRBASE: .res 1 ; High byte of screen base
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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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defpalette: .res $0100
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palette: .res $0100
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bcolor := palette + 0 ; Background color
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color: .res 1 ; Stroke and fill index
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text_mode: .res 1 ; Old text mode
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.data
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error: .byte TGI_ERR_OK ; Error code
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; Constants and tables
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.rodata
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; Bit masks for setting pixels
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bitMasks1:
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.byte %10000000, %01000000, %00100000, %00010000
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.byte %00001000, %00000100, %00000010, %00000001
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bitMasks2:
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.byte %01111111, %10111111, %11011111, %11101111
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.byte %11110111, %11111011, %11111101, %11111110
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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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INSTALL:
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; Create the default palette.
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ldx #$00
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: txa
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sta defpalette,x
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inx
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bnz :-
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; Fall through.
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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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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 called only once; so, any code that is needed
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; to initiate variables and so on must go here. Setting the palette is not
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; needed because that is called by the graphics kernel later.
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; The graphics kernel never will call INIT when a graphics mode already is
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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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INIT: stz error ; #TGI_ERR_OK
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; Save the current text mode.
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sec
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jsr SCREEN_MODE
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sta text_mode
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; Switch into (640 x 480 x 2) graphics mode.
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lda #%00000000 ; DCSEL = 0, VRAM port 1
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sta VERA::CTRL
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lda #%00100001 ; Disable sprites, layer 1 enable, VGA
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sta VERA::DISP::VIDEO
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lda #%00000100 ; Bitmap mode enable
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sta VERA::L1::CONFIG
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lda #%00000001 ; Tile width 640
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sta VERA::L1::TILE_BASE
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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 never will 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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DONE:
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jsr CINT
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lda text_mode
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clc
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jmp SCREEN_MODE
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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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lda error
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stz 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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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: Clear the screen.
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;
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; Must set an error code: NO
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CLEAR:
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.scope inner
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; set up DCSEL=2
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lda #(2 << 1)
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sta VERA::CTRL
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; set cache writes
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lda #$40
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tsb $9f29 ;VERA_FX_CTRL
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; set FX cache to all zeroes
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lda #(6 << 1)
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sta VERA::CTRL
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lda #$00 ; color
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; $00=black, $01=white
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beq ahead
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lda #$ff
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ahead:
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sta VERA::DISP::VIDEO
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sta VERA::DISP::HSCALE ;$9f2a
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sta VERA::DISP::VSCALE ;$9f2b
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sta VERA::DISP::FRAME ;$9f2c
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stz VERA::CTRL
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; set address and increment for bitmap area
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stz VERA::ADDR
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stz VERA::ADDR + 1
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lda #$30 ; increment +4
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sta VERA::ADDR + 2
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ldy #240 ; number of rows
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blank_outer:
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ldx #10 ; 10 iterations of 32 = one line of 640
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blank_loop:
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.repeat 8
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stz VERA::DATA0 ; $9f23 each `stz` writes four zeroes to VRAM (cache contents) for a total of 32 pixels when repeated 8x
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.endrep
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dex
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bne blank_loop
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dey
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bne blank_outer
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; set up DCSEL=2
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lda #(2 << 1)
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sta VERA::CTRL ; $9f25
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; set FX off (cache write bit 1 -> 0)
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stz $9f29 ;VERA_FX_CTRL
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stz VERA::CTRL
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.endscope
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rts
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; ------------------------------------------------------------------------
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; SETVIEWPAGE: Set the visible page. Called with the new page in .A (0..n-1).
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; The page number already is checked to be valid by the graphics kernel.
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;
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; Must set an error code: NO (will be called only if page OK)
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SETVIEWPAGE:
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; Fall through.
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; ------------------------------------------------------------------------
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; SETDRAWPAGE: Set the drawable page. Called with the new page in .A (0..n-1).
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; The page number already is checked to be valid by the graphics kernel.
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;
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; Must set an error code: NO (will be called only if page OK)
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SETDRAWPAGE:
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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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SETPALETTE:
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stz error ; #TGI_ERR_OK
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ldy #$00
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: lda (ptr1),y
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sta palette,y
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iny
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bnz :-
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lda color ; Get stroke and fill index
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; Fall through.
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; ------------------------------------------------------------------------
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; SETCOLOR: Set the drawing color (in .A). The new color already is checked
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; to be in a valid range (0..maxcolor).
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;
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; Must set an error code: NO (will be called only if color OK)
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SETCOLOR:
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tax
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beq @L1
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lda #$FF
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@L1: sta BITMASK
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rts
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; ------------------------------------------------------------------------
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; GETPALETTE: Return the current palette in .XA. 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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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 .XA. 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 changable) 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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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 co-ordinates passed to this function never are 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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SETPIXEL:
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jsr CALC
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stx TEMP
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lda ADDR
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ldy ADDR+1
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ldx #$00
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sta VERA::ADDR
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sty VERA::ADDR + 1
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stx VERA::ADDR + 2
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ldx TEMP
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lda BITMASK
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beq @ahead
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; if COLOR = 1, white is line color
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; Set the bit in the byte at VERA_DATA0
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lda VERA::DATA0 ; Load the byte at memory address
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ora bitMasks1,X ; OR with the bit mask
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sta VERA::DATA0 ; Store back the modified byte
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rts
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@ahead:
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; if COLOR = 0, black is line color
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lda VERA::DATA0 ; Load the byte at memory address
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and bitMasks2,X ; OR with the bit mask
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sta VERA::DATA0 ; Store back the modified byte
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rts
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; ------------------------------------------------------------------------
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; GETPIXEL: Read the color value of a pixel, and return it in .XA. The
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; co-ordinates passed to this function never are 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
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stx TEMP
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lda ADDR
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ldy ADDR+1
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ldx #$00
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sta VERA::ADDR
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sty VERA::ADDR + 1
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stx VERA::ADDR + 2
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ldx TEMP
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lda VERA::DATA0 ; Load the byte at memory address
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and bitMasks1,X
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bne @ahead
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ldx #$00
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lda #$00
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rts
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@ahead:
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ldx #$00
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lda #$01
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rts
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; ------------------------------------------------------------------------
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; BAR: Draw a filled rectangle with the corners X1/Y1, X2/Y2, where
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; X1/Y1 = ptr1/ptr2 and X2/Y2 = ptr3/ptr4, using the current drawing color.
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; Contrary to most other functions, the graphics kernel will sort and clip
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; the co-ordinates before calling the driver; so on entry, the following
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; conditions are valid:
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; X1 <= X2
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; Y1 <= Y2
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; (X1 >= 0) && (X1 < XRES)
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; (X2 >= 0) && (X2 < XRES)
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; (Y1 >= 0) && (Y1 < YRES)
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; (Y2 >= 0) && (Y2 < YRES)
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;
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; Must set an error code: NO
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BAR:
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; Initialize tempY with Y1
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lda Y1
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sta tempY
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lda Y1+1
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sta tempY+1
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@outer_loop:
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; Compare tempY with Y2
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lda tempY+1
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cmp Y2+1
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bcc @outer_continue ; If tempY high byte < Y2 high byte, continue
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bne @outer_end ; If tempY high byte > Y2 high byte, end
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lda tempY
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cmp Y2
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bcc @outer_continue ; If tempY low byte < Y2 low byte, continue
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beq @outer_end ; If tempY low byte = Y2 low byte, end
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@outer_continue:
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; Initialize tempX with X1
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lda X1
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sta tempX
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lda X1+1
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sta tempX+1
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@inner_loop:
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; Compare tempX with X2
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lda tempX+1
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cmp X2+1
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bcc @inner_continue ; If tempX high byte < X2 high byte, continue
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bne @inner_end ; If tempX high byte > X2 high byte, end
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lda tempX
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cmp X2
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bcc @inner_continue ; If tempX low byte < X2 low byte, continue
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@inner_end:
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; Increment tempY
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inc tempY
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bne @outer_loop ; If no overflow, continue outer loop
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inc tempY+1 ; If overflow, increment high byte
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@inner_continue:
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; Call setpixel(tempX, tempY)
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lda X1
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pha
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lda X1+1
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pha
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lda Y1
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pha
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lda Y1+1
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pha
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lda tempX
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ldx tempX+1
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sta X1
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stx X1+1
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lda tempY
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ldx tempY+1
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sta Y1
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stx Y1+1
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jsr SETPIXEL
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pla
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sta Y1+1
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pla
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sta Y1
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pla
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sta X1+1
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pla
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sta X1
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; Increment tempX
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inc tempX
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bne @inner_loop_check ; If no overflow, continue
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inc tempX+1 ; If overflow, increment high byte
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@inner_loop_check:
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; Compare tempX with X2 again after increment
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lda tempX+1
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cmp X2+1
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bcc @inner_continue ; If tempX high byte < X2 high byte, continue
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bne @outer_increment ; If tempX high byte > X2 high byte, increment tempY
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lda tempX
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cmp X2
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bcc @inner_continue ; If tempX low byte < X2 low byte, continue
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@outer_increment:
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; Increment tempY
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inc tempY
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bne @outer_loop ; If no overflow, continue outer loop
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inc tempY+1 ; If overflow, increment high byte
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@outer_end:
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jmp @done
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@done:
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rts
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; ------------------------------------------------------------------------
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; TEXTSTYLE: Set the style used when calling OUTTEXT. Text scaling in X and Y
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; directions are passed in .X and .Y, the text direction is passed in .A.
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;
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; Must set an error code: NO
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TEXTSTYLE:
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rts
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; ------------------------------------------------------------------------
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; OUTTEXT: Output text at X/Y = ptr1/ptr2 using the current color and the
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; current text style. The text to output is given as a zero-terminated
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; string with address in ptr3.
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;
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; Must set an error code: NO
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OUTTEXT:
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rts
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; ------------------------------------------------------------------------
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; Calculate all variables to plot the pixel at X1/Y1.
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;------------------------
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;< X1,Y1 - pixel
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;> ADDR - address of card
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;> X - bit number (X1 & 7)
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CALC:
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lda Y1+1
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sta ADDR+1
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lda Y1
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asl
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rol ADDR+1
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asl
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rol ADDR+1 ; Y*4
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clc
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|
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
|
|
lda X1
|
|
and #7
|
|
tax
|
|
rts
|
|
|
|
|
|
.include "../../tgi/tgidrv_line.inc"
|