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https://github.com/cc65/cc65.git
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626 lines
11 KiB
ArmAsm
626 lines
11 KiB
ArmAsm
;
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; Graphics driver for the 40x48x16 mode on the Apple II
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;
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; Stefan Haubenthal <polluks@sdf.lonestar.org>
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; Oliver Schmidt <ol.sc@web.de>
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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-mode.inc"
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.include "tgi-error.inc"
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.include "apple2.inc"
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; ------------------------------------------------------------------------
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; Zero page stuff
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H2 := $2C
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COLOR := $30
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; ROM entry points
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TEXT := $F399
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PLOT := $F800
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HLINE := $F819
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CLRSC2 := $F838
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SETCOL := $F864
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SCRN := $F871
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SETGR := $FB40
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HOME := $FC58
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; ------------------------------------------------------------------------
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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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TEMP := tmp3
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TEMP2 := tmp4
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TEMP3 := sreg
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TEMP4 := sreg+1
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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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; ------------------------------------------------------------------------
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.segment "JUMPTABLE"
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; Header. Includes jump table and constants.
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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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.word 40 ; X resolution
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.word 48 ; Y resolution
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.byte 16 ; 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 $100 ; Aspect ratio
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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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.bss
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; Absolute variables used in the code
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ERROR: .res 1 ; Error code
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MIX: .res 1 ; 4 lines of text
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; Line routine stuff
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COUNT: .res 2
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NY: .res 2
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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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; ------------------------------------------------------------------------
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.rodata
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; Constants and tables
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DEFPALETTE: .byte $00, $01, $02, $03, $04, $05, $06, $07
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.byte $08, $09, $0A, $0B, $0C, $0D, $0E, $0F
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MAXY: .byte 47, 39
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; ------------------------------------------------------------------------
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.code
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; INIT: Changes an already installed device from text mode to graphics 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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; Must set an error code: YES
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INIT:
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; Switch into graphics mode
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bit $C082 ; Switch in ROM
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jsr SETGR
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bit MIXCLR
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bit $C080 ; Switch in LC bank 2 for R/O
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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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sta MIX
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; Fall through
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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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; Must set an error code: NO
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INSTALL:
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; Fall through
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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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; Must set an error code: NO
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UNINSTALL:
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; Fall through
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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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; Must set an error code: NO (will only be called if page ok)
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SETVIEWPAGE:
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; Fall through
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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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; Must set an error code: NO (will only be called if page ok)
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SETDRAWPAGE:
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; Fall through
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; TEXTSTYLE: Set the style used when calling OUTTEXT. Text scaling in X and Y
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; direction is passend in X/Y, the text direction is passed in A.
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; Must set an error code: NO
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TEXTSTYLE:
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; Fall through
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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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; Must set an error code: NO
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OUTTEXT:
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rts
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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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; Must set an error code: NO
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DONE:
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bit $C082 ; Switch in ROM
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jsr TEXT
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jsr HOME
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bit $C080 ; Switch in LC bank 2 for R/O
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rts
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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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ldx #TGI_ERR_OK
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stx ERROR
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rts
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; CLEAR: Clears the screen.
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; Must set an error code: NO
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CLEAR:
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bit $C082 ; Switch in ROM
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lda COLOR ; Save current drawing color
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pha
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ldx MIX
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ldy MAXY,x ; Max Y depends on 4 lines of text
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jsr CLRSC2
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pla
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sta COLOR ; Save current drawing color
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bit $C080 ; Switch in LC bank 2 for R/O
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rts
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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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; Must set an error code: NO (will only be called if color ok)
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SETCOLOR:
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bit $C082 ; Switch in ROM
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jsr SETCOL
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bit $C080 ; Switch in LC bank 2 for R/O
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rts
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; CONTROL: Platform/driver specific entry point.
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; Must set an error code: YES
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CONTROL:
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; Check data msb and code to be 0
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ora ptr1+1
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bne err
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; Check data lsb to be [0..1]
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lda ptr1
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cmp #1+1
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bcs err
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bit $C082 ; Switch in ROM
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; Switch 4 lines of text
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tax
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.assert MIXCLR + 1 = MIXSET, error
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lda MIXCLR,x ; No BIT absolute,X available
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; Save current switch setting
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txa
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sta MIX
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bne text
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; Clear 8 lines of graphics
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lda COLOR ; Save current drawing color
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pha
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lda #39 ; Rightmost column
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sta H2
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ldx #40 ; First line
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: txa
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ldy #$00 ; Leftmost column
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sty COLOR ; Black
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jsr HLINE ; Preserves X
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inx
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cpx #47+1 ; Last line
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bcc :-
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pla
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sta COLOR ; Save current drawing color
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bcs :+ ; Branch always
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; Clear 4 lines of text
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text: jsr HOME
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: bit $C080 ; Switch in LC bank 2 for R/O
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; Done, reset the error code
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lda #TGI_ERR_OK
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beq :+ ; Branch always
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; Done, set the error code
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err: lda #TGI_ERR_INV_ARG
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: sta ERROR
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rts
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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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; Must set an error code: YES
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SETPALETTE:
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lda #TGI_ERR_INV_FUNC
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sta ERROR
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rts
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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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; Must set an error code: NO
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GETPALETTE:
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; Fall through
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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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; 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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; 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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; Must set an error code: NO
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SETPIXEL:
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bit $C082 ; Switch in ROM
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ldy X1
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lda Y1
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jsr PLOT
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bit $C080 ; Switch in LC bank 2 for R/O
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rts
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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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bit $C082 ; Switch in ROM
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ldy X1
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lda Y1
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jsr SCRN
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ldx #$00
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bit $C080 ; Switch in LC bank 2 for R/O
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rts
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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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; Must set an error code: NO
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LINE:
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; nx = abs (x2 - x1)
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sec
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lda X2
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sbc X1
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sta NX
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lda X2+1
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sbc X1+1
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tay
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lda NX
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jsr abs
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sta NX
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sty NX+1
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; ny = abs (y2 - y1)
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sec
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lda Y2
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sbc Y1
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sta NY
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lda Y2+1
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sbc Y1+1
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tay
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lda NY
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jsr abs
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sta NY
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sty NY+1
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; if (x2 >= x1)
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ldx #X2
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lda X1
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ldy X1+1
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jsr icmp
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bcc :+
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; dx = 1
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lda #$01
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bne :++
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; else
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; dx = -1
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: lda #$FF
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: sta DX
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; if (y2 >= y1)
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ldx #Y2
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lda Y1
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ldy Y1+1
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jsr icmp
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bcc :+
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; dy = 1
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lda #$01
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bne :++
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; else
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; dy = -1
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: lda #$FF
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: sta DY
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; err = ax = ay = 0
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lda #$00
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sta ERR
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sta ERR+1
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sta AX
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sta AY
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; if (nx < ny) {
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ldx #NX
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lda NY
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ldy NY+1
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jsr icmp
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bcs :+
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; nx <-> ny
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lda NX
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ldx NY
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sta NY
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stx NX
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lda NX+1
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ldx NY+1
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sta NY+1
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stx NX+1
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; ax = dx
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lda DX
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sta AX
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; ay = dy
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lda DY
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sta AY
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; dx = dy = 0 }
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lda #$00
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sta DX
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sta DY
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; ny = - ny
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: lda NY
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ldy NY+1
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jsr neg
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sta NY
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sty NY+1
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; for (count = nx; count > 0; --count) {
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lda NX
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ldx NX+1
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sta COUNT
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stx COUNT+1
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for: lda COUNT ; count > 0
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ora COUNT+1
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bne :+
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rts
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; setpixel (X1, Y1)
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: jsr SETPIXEL
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; pb = err + ny
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clc
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lda ERR
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adc NY
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sta PB
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lda ERR+1
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adc NY+1
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sta PB+1
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tax
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; ub = pb + nx
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clc
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lda PB
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adc NX
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sta UB
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txa
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adc NX+1
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sta UB+1
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; x1 = x1 + dx
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ldx #$00
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lda DX
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bpl :+
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dex
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: clc
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adc X1
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sta X1
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txa
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adc X1+1
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sta X1+1
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; y1 = y1 + ay
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ldx #$00
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lda AY
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bpl :+
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dex
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: clc
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adc Y1
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sta Y1
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txa
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adc Y1+1
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sta Y1+1
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; if (abs (pb) < abs (ub)) {
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lda PB
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ldy PB+1
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jsr abs
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sta TEMP3
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sty TEMP4
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lda UB
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ldy UB+1
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jsr abs
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ldx #TEMP3
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jsr icmp
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bpl :+
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; err = pb }
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lda PB
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ldx PB+1
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jmp next
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; else { x1 = x1 + ax
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: ldx #$00
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lda AX
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bpl :+
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dex
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: clc
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adc X1
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sta X1
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txa
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adc X1+1
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sta X1+1
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; y1 = y1 + dy
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ldx #$00
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lda DY
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bpl :+
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dex
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: clc
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adc Y1
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sta Y1
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txa
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adc Y1+1
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sta Y1+1
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; err = ub }
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lda UB
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ldx UB+1
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next: sta ERR
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stx ERR+1
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; } (--count)
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lda COUNT
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sec
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sbc #$01
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sta COUNT
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bcc :+
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jmp for
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: dec COUNT+1
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jmp for
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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 coordinates 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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; Must set an error code: NO
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BAR:
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bit $C082 ; Switch in ROM
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lda X2
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sta H2
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inc Y2
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ldx Y1
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: txa
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ldy X1
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jsr HLINE ; Preserves X
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inx
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cpx Y2
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bcc :-
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bit $C080 ; Switch in LC bank 2 for R/O
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rts
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; Copies of some runtime routines
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abs:
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; A/Y := abs (A/Y)
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cpy #$00
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bpl :+
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; A/Y := neg (A/Y)
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neg: clc
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eor #$FF
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adc #$01
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pha
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tya
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eor #$FF
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adc #$00
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tay
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pla
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: rts
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icmp:
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; Compare A/Y to zp,X
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sta TEMP ; TEMP/TEMP2 - arg2
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sty TEMP2
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lda $00,x
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pha
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lda $01,x
|
|
tay
|
|
pla
|
|
tax
|
|
tya ; X/A - arg1 (a = high)
|
|
|
|
sec
|
|
sbc TEMP2
|
|
bne :++
|
|
cpx TEMP
|
|
beq :+
|
|
adc #$FF
|
|
ora #$01
|
|
: rts
|
|
: bvc :+
|
|
eor #$FF
|
|
ora #$01
|
|
: rts
|