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https://github.com/cc65/cc65.git
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Up to now static drivers were created via co65 from dynamic drivers. However there was an issue with that approach: The dynamic drivers are "o65 simple files" which obligates that they start with the 'code' segment. However dynamic drivers need to start with the module header - which is written to. For dynamic drivers this isn't more than a conceptual issue because they are always contain a 'data' segment and may therefore only be loaded into writable memory. However when dynamic drivers are converted to static drivers using co65 then that issue becomes a real problem as then the 'code' segment may end up in non-writable memory - and thus writing to the module header fails. Instead of changing the way dynamic drivers work I opted to rather make static driver creation totally independent from dynamic drivers. This allows to place the module header in the 'data' segment (see 'module.mac').
962 lines
24 KiB
ArmAsm
962 lines
24 KiB
ArmAsm
;
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; Graphics driver for the 320x200x2 mode on the C64.
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;
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; Based on Stephen L. Judds GRLIB code
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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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.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 _c64_hi_tgi
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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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.addr $0000 ; Library reference
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.word 320 ; X resolution
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.word 200 ; Y resolution
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.byte 2 ; Number of drawing colors
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.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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.word $00D4 ; Aspect ratio (based on 4/3 display)
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.byte 0 ; TGI driver flags
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; Next comes the jump table. With the exception of IRQ, all entries must be
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; valid 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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.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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TEXT := ptr3
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ROW := tmp2 ; Bitmap row...
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COL := tmp3 ; ...and column, both set by PLOT
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TEMP := tmp4
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TEMP2 := sreg
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POINT := regsave
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INRANGE := regsave+2 ; PLOT variable, $00 = coordinates in range
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CHUNK := X2 ; Used in the line routine
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OLDCHUNK := X2+1 ; Dito
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; Absolute variables used in the code
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.bss
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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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; INIT/DONE
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OLDD018: .res 1 ; Old register value
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; Line routine stuff
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DX: .res 2
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DY: .res 2
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; BAR variables
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X1SAVE: .res 2
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Y1SAVE: .res 2
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X2SAVE: .res 2
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Y2SAVE: .res 2
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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, $01 ; 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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BITCHUNK: .byte $FF,$7F,$3F,$1F,$0F,$07,$03,$01
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CHARROM := $D000 ; Character rom base address
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CBASE := $D000 ; Color memory base address
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VBASE := $E000 ; Video memory base address
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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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rts
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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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ldx #$FF
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stx BITMASK
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; Switch into graphics mode
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lda $DD02 ; Set the data direction regs
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ora #3
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sta $DD02
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lda $DD00
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and #$FC ; Switch to bank 3
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sta $DD00
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lda $D018
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sta OLDD018
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lda #$48 ; Set color map to $D000, screen to $E000
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sta $D018
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lda $D011 ; And turn on bitmap
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ora #$20
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DONE1: sta $D011
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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: lda $DD02 ; Set the data direction regs
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ora #3
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sta $DD02
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lda $DD00
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ora #$03 ; Bank 0
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sta $DD00
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lda OLDD018 ; Screen mem --> $0400
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sta $D018
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lda $D011
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and #<~$20
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sta $D011
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rts
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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: ldy #$00
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tya
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@L1: sta VBASE+$0000,y
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sta VBASE+$0100,y
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sta VBASE+$0200,y
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sta VBASE+$0300,y
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sta VBASE+$0400,y
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sta VBASE+$0500,y
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sta VBASE+$0600,y
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sta VBASE+$0700,y
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sta VBASE+$0800,y
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sta VBASE+$0900,y
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sta VBASE+$0A00,y
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sta VBASE+$0B00,y
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sta VBASE+$0C00,y
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sta VBASE+$0D00,y
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sta VBASE+$0E00,y
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sta VBASE+$0F00,y
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sta VBASE+$1000,y
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sta VBASE+$1100,y
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sta VBASE+$1200,y
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sta VBASE+$1300,y
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sta VBASE+$1400,y
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sta VBASE+$1500,y
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sta VBASE+$1600,y
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sta VBASE+$1700,y
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sta VBASE+$1800,y
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sta VBASE+$1900,y
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sta VBASE+$1A00,y
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sta VBASE+$1B00,y
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sta VBASE+$1C00,y
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sta VBASE+$1D00,y
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sta VBASE+$1E00,y
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sta VBASE+$1F00,y
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iny
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bne @L1
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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).
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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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rts
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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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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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lda PALETTE+1 ; Foreground color
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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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ora PALETTE ; Background color
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tax
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; Initialize the color map with the new color settings (it is below the
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; I/O area)
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ldy #$00
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sei
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lda $01 ; Get ROM config
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pha ; Save it
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and #%11111100 ; Clear bit 0 and 1
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sta $01
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txa ; Load color code
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@L2: sta CBASE+$0000,y
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sta CBASE+$0100,y
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sta CBASE+$0200,y
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sta CBASE+$0300,y
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iny
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bne @L2
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pla
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sta $01
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cli
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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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; 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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SETPIXEL:
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jsr CALC ; Calculate coordinates
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sei ; Get underneath ROM
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lda $01
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pha
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lda #$34
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sta $01
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lda (POINT),Y
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eor BITMASK
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and BITTAB,X
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eor (POINT),Y
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sta (POINT),Y
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pla
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sta $01
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cli
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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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sei ; Get underneath ROM
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lda $01
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pha
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lda #$34
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sta $01
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lda (POINT),Y
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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: pla
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sta $01
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cli
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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
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; X2/Y2 = ptr3/ptr4 using the current drawing color.
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;
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; To deal with off-screen coordinates, the current row
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; and column (40x25) is kept track of. These are set
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; negative when the point is off the screen, and made
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; positive when the point is within the visible screen.
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;
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; X1,X2 etc. are set up above (x2=LINNUM in particular)
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; Format is LINE x2,y2,x1,y1
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;
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; Must set an error code: NO
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;
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LINE:
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@CHECK: lda X2 ;Make sure x1<x2
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sec
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sbc X1
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tax
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lda X2+1
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sbc X1+1
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bpl @CONT
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lda Y2 ;If not, swap P1 and P2
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ldy Y1
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sta Y1
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sty Y2
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lda Y2+1
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ldy Y1+1
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sta Y1+1
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sty Y2+1
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lda X1
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ldy X2
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sty X1
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sta X2
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lda X2+1
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ldy X1+1
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sta X1+1
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sty X2+1
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bcc @CHECK
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@CONT: sta DX+1
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stx DX
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ldx #$C8 ;INY
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lda Y2 ;Calculate dy
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sec
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sbc Y1
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tay
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lda Y2+1
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sbc Y1+1
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bpl @DYPOS ;Is y2>=y1?
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lda Y1 ;Otherwise dy=y1-y2
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sec
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sbc Y2
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tay
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ldx #$88 ;DEY
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@DYPOS: sty DY ; 8-bit DY -- FIX ME?
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stx YINCDEC
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stx XINCDEC
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jsr CALC ; Set up .X,.Y,POINT, and INRANGE
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lda BITCHUNK,X
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sta OLDCHUNK
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sta CHUNK
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sei ; Get underneath ROM
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lda #$34
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sta $01
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ldx DY
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cpx DX ;Who's bigger: dy or dx?
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bcc STEPINX ;If dx, then...
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lda DX+1
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bne STEPINX
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;
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; Big steps in Y
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;
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; To simplify my life, just use PLOT to plot points.
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;
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; No more!
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; Added special plotting routine -- cool!
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;
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; X is now counter, Y is y-coordinate
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;
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; On entry, X=DY=number of loop iterations, and Y=
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; Y1 AND #$07
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STEPINY:
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lda #00
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sta OLDCHUNK ;So plotting routine will work right
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lda CHUNK
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lsr ;Strip the bit
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eor CHUNK
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sta CHUNK
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txa
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bne @CONT ;If dy=0 it's just a point
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inx
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@CONT: lsr ;Init counter to dy/2
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;
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; Main loop
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;
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YLOOP: sta TEMP
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lda INRANGE ;Range check
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bne @SKIP
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lda (POINT),y ;Otherwise plot
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eor BITMASK
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and CHUNK
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eor (POINT),y
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sta (POINT),y
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@SKIP:
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YINCDEC:
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iny ;Advance Y coordinate
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cpy #8
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bcc @CONT ;No prob if Y=0..7
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jsr FIXY
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@CONT: lda TEMP ;Restore A
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sec
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sbc DX
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bcc YFIXX
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YCONT: dex ;X is counter
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bne YLOOP
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YCONT2: lda (POINT),y ;Plot endpoint
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eor BITMASK
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and CHUNK
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eor (POINT),y
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sta (POINT),y
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YDONE: lda #$36
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sta $01
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cli
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rts
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YFIXX: ;x=x+1
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adc DY
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lsr CHUNK
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bne YCONT ;If we pass a column boundary...
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ror CHUNK ;then reset CHUNK to $80
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sta TEMP2
|
|
lda COL
|
|
bmi @C1 ;Skip if column is negative
|
|
cmp #39 ;End if move past end of screen
|
|
bcs YDONE
|
|
@C1: lda POINT ;And add 8 to POINT
|
|
adc #8
|
|
sta POINT
|
|
bcc @CONT
|
|
inc POINT+1
|
|
@CONT: inc COL ;Increment column
|
|
bne @C2
|
|
lda ROW ;Range check
|
|
cmp #25
|
|
bcs @C2
|
|
lda #00 ;Passed into col 0
|
|
sta INRANGE
|
|
@C2: lda TEMP2
|
|
dex
|
|
bne YLOOP
|
|
beq YCONT2
|
|
|
|
;
|
|
; Big steps in X direction
|
|
;
|
|
; On entry, X=DY=number of loop iterations, and Y=
|
|
; Y1 AND #$07
|
|
|
|
.bss
|
|
COUNTHI:
|
|
.byte $00 ;Temporary counter
|
|
;only used once
|
|
.code
|
|
STEPINX:
|
|
ldx DX
|
|
lda DX+1
|
|
sta COUNTHI
|
|
cmp #$80
|
|
ror ;Need bit for initialization
|
|
sta Y1 ;High byte of counter
|
|
txa
|
|
bne @CONT ;Could be $100
|
|
dec COUNTHI
|
|
@CONT: ror
|
|
;
|
|
; Main loop
|
|
;
|
|
XLOOP: lsr CHUNK
|
|
beq XFIXC ;If we pass a column boundary...
|
|
XCONT1: sbc DY
|
|
bcc XFIXY ;Time to step in Y?
|
|
XCONT2: dex
|
|
bne XLOOP
|
|
dec COUNTHI ;High bits set?
|
|
bpl XLOOP
|
|
|
|
XDONE: lsr CHUNK ;Advance to last point
|
|
jsr LINEPLOT ;Plot the last chunk
|
|
EXIT: lda #$36
|
|
sta $01
|
|
cli
|
|
rts
|
|
;
|
|
; CHUNK has passed a column, so plot and increment pointer
|
|
; and fix up CHUNK, OLDCHUNK.
|
|
;
|
|
XFIXC: sta TEMP
|
|
jsr LINEPLOT
|
|
lda #$FF
|
|
sta CHUNK
|
|
sta OLDCHUNK
|
|
lda COL
|
|
bmi @C1 ;Skip if column is negative
|
|
cmp #39 ;End if move past end of screen
|
|
bcs EXIT
|
|
@C1: lda POINT
|
|
adc #8
|
|
sta POINT
|
|
bcc @CONT
|
|
inc POINT+1
|
|
@CONT: inc COL
|
|
bne @C2
|
|
lda ROW
|
|
cmp #25
|
|
bcs @C2
|
|
lda #00
|
|
sta INRANGE
|
|
@C2: lda TEMP
|
|
sec
|
|
bcs XCONT1
|
|
;
|
|
; Check to make sure there isn't a high bit, plot chunk,
|
|
; and update Y-coordinate.
|
|
;
|
|
XFIXY: dec Y1 ;Maybe high bit set
|
|
bpl XCONT2
|
|
adc DX
|
|
sta TEMP
|
|
lda DX+1
|
|
adc #$FF ;Hi byte
|
|
sta Y1
|
|
|
|
jsr LINEPLOT ;Plot chunk
|
|
lda CHUNK
|
|
sta OLDCHUNK
|
|
|
|
lda TEMP
|
|
XINCDEC:
|
|
iny ;Y-coord
|
|
cpy #8 ;0..7 is ok
|
|
bcc XCONT2
|
|
sta TEMP
|
|
jsr FIXY
|
|
lda TEMP
|
|
jmp XCONT2
|
|
|
|
;
|
|
; Subroutine to plot chunks/points (to save a little
|
|
; room, gray hair, etc.)
|
|
;
|
|
LINEPLOT: ; Plot the line chunk
|
|
lda INRANGE
|
|
bne @SKIP
|
|
|
|
lda (POINT),Y ; Otherwise plot
|
|
eor BITMASK
|
|
ora CHUNK
|
|
and OLDCHUNK
|
|
eor CHUNK
|
|
eor (POINT),Y
|
|
sta (POINT),Y
|
|
@SKIP: rts
|
|
|
|
;
|
|
; Subroutine to fix up pointer when Y decreases through
|
|
; zero or increases through 7.
|
|
;
|
|
FIXY: cpy #255 ;Y=255 or Y=8
|
|
beq @DECPTR
|
|
@INCPTR: ;Add 320 to pointer
|
|
ldy #0 ;Y increased through 7
|
|
lda ROW
|
|
bmi @C1 ;If negative, then don't update
|
|
cmp #24
|
|
bcs @TOAST ;If at bottom of screen then quit
|
|
@C1: lda POINT
|
|
adc #<320
|
|
sta POINT
|
|
lda POINT+1
|
|
adc #>320
|
|
sta POINT+1
|
|
@CONT1: inc ROW
|
|
bne @DONE
|
|
lda COL
|
|
bpl @CLEAR
|
|
@DONE: rts
|
|
|
|
@DECPTR: ;Okay, subtract 320 then
|
|
ldy #7 ;Y decreased through 0
|
|
lda POINT
|
|
sec
|
|
sbc #<320
|
|
sta POINT
|
|
lda POINT+1
|
|
sbc #>320
|
|
sta POINT+1
|
|
@CONT2: dec ROW
|
|
bmi @TOAST
|
|
lda ROW
|
|
cmp #24
|
|
bne @DONE
|
|
lda COL
|
|
bmi @DONE
|
|
@CLEAR: lda #00
|
|
sta INRANGE
|
|
rts
|
|
|
|
@TOAST: pla ;Remove old return address
|
|
pla
|
|
jmp EXIT ;Restore interrupts, etc.
|
|
|
|
; ------------------------------------------------------------------------
|
|
; 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
|
|
;
|
|
|
|
; Note: This function needs optimization. It's just a cheap translation of
|
|
; the original C wrapper and could be written much smaller (besides that,
|
|
; calling LINE is not a good idea either).
|
|
|
|
BAR: lda Y2
|
|
sta Y2SAVE
|
|
lda Y2+1
|
|
sta Y2SAVE+1
|
|
|
|
lda X2
|
|
sta X2SAVE
|
|
lda X2+1
|
|
sta X2SAVE+1
|
|
|
|
lda Y1
|
|
sta Y1SAVE
|
|
lda Y1+1
|
|
sta Y1SAVE+1
|
|
|
|
lda X1
|
|
sta X1SAVE
|
|
lda X1+1
|
|
sta X1SAVE+1
|
|
|
|
@L1: lda Y1
|
|
sta Y2
|
|
lda Y1+1
|
|
sta Y2+1
|
|
jsr LINE
|
|
|
|
lda Y1SAVE
|
|
cmp Y2SAVE
|
|
bne @L2
|
|
lda Y1SAVE
|
|
cmp Y2SAVE
|
|
beq @L4
|
|
|
|
@L2: inc Y1SAVE
|
|
bne @L3
|
|
inc Y1SAVE+1
|
|
|
|
@L3: lda Y1SAVE
|
|
sta Y1
|
|
lda Y1SAVE+1
|
|
sta Y1+1
|
|
|
|
lda X1SAVE
|
|
sta X1
|
|
lda X1SAVE+1
|
|
sta X1+1
|
|
|
|
lda X2SAVE
|
|
sta X2
|
|
lda X2SAVE+1
|
|
sta X2+1
|
|
jmp @L1
|
|
|
|
@L4: rts
|
|
|
|
|
|
; ------------------------------------------------------------------------
|
|
; 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:
|
|
|
|
; Calculate a pointer to the representation of the character in the
|
|
; character ROM
|
|
|
|
ldx #((>(CHARROM + $0800)) >> 3)
|
|
ldy #0
|
|
lda (TEXT),y
|
|
bmi @L1
|
|
ldx #((>(CHARROM + $0000)) >> 3)
|
|
@L1: stx ptr4+1
|
|
asl a
|
|
rol ptr4+1
|
|
asl a
|
|
rol ptr4+1
|
|
asl a
|
|
rol ptr4+1
|
|
sta ptr4
|
|
|
|
|
|
|
|
|
|
|
|
rts
|
|
|
|
; ------------------------------------------------------------------------
|
|
; Calculate all variables to plot the pixel at X1/Y1. If the point is out
|
|
; of range, a carry is returned and INRANGE is set to a value !0 zero. If
|
|
; the coordinates are valid, INRANGE is zero and the carry clear.
|
|
|
|
CALC: lda Y1
|
|
sta ROW
|
|
and #7
|
|
tay
|
|
lda Y1+1
|
|
lsr ; Neg is possible
|
|
ror ROW
|
|
lsr
|
|
ror ROW
|
|
lsr
|
|
ror ROW
|
|
|
|
lda #00
|
|
sta POINT
|
|
lda ROW
|
|
cmp #$80
|
|
ror
|
|
ror POINT
|
|
cmp #$80
|
|
ror
|
|
ror POINT ; row*64
|
|
adc ROW ; +row*256
|
|
clc
|
|
adc #>VBASE ; +bitmap base
|
|
sta POINT+1
|
|
|
|
lda X1
|
|
tax
|
|
sta COL
|
|
lda X1+1
|
|
lsr
|
|
ror COL
|
|
lsr
|
|
ror COL
|
|
lsr
|
|
ror COL
|
|
|
|
txa
|
|
and #$F8
|
|
clc
|
|
adc POINT ; +(X AND #$F8)
|
|
sta POINT
|
|
lda X1+1
|
|
adc POINT+1
|
|
sta POINT+1
|
|
txa
|
|
and #7
|
|
tax
|
|
|
|
lda ROW
|
|
cmp #25
|
|
bcs @L9
|
|
lda COL
|
|
cmp #40
|
|
bcs @L9
|
|
lda #00
|
|
@L9: sta INRANGE
|
|
rts
|
|
|
|
|