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cc65/libsrc/apple2/tgi/a2.lo.s

348 lines
11 KiB
ArmAsm

;
; Graphics driver for the 40x48x16 mode on the Apple II
;
; Stefan Haubenthal <polluks@sdf.lonestar.org>
; Oliver Schmidt <ol.sc@web.de>
;
.include "zeropage.inc"
.include "tgi-kernel.inc"
.include "tgi-error.inc"
.include "apple2.inc"
; ------------------------------------------------------------------------
; Zero page stuff
H2 := $2C
COLOR := $30
; ROM entry points
TEXT := $F399
PLOT := $F800
HLINE := $F819
CLRSC2 := $F838
SETCOL := $F864
SCRN := $F871
SETGR := $FB40
HOME := $FC58
; Used for passing parameters to the driver
X1 := ptr1
Y1 := ptr2
X2 := ptr3
Y2 := ptr4
; ------------------------------------------------------------------------
.segment "JUMPTABLE"
; Header. Includes jump table and constants.
; First part of the header is a structure that has a magic and defines the
; capabilities of the driver
.byte $74, $67, $69 ; "tgi"
.byte TGI_API_VERSION ; TGI API version number
.word 40 ; X resolution
.word 48 ; Y resolution
.byte 16 ; Number of drawing colors
.byte 1 ; Number of screens available
.byte 8 ; System font X size
.byte 8 ; System font Y size
.word $0198 ; Aspect ratio (based on 4/3 display)
.byte 0 ; TGI driver flags
; Next comes the jump table. With the exception of IRQ, all entries must be
; valid and may point to an RTS for test versions (function not implemented).
.addr INSTALL
.addr UNINSTALL
.addr INIT
.addr DONE
.addr GETERROR
.addr CONTROL
.addr CLEAR
.addr SETVIEWPAGE
.addr SETDRAWPAGE
.addr SETCOLOR
.addr SETPALETTE
.addr GETPALETTE
.addr GETDEFPALETTE
.addr SETPIXEL
.addr GETPIXEL
.addr LINE
.addr BAR
.addr TEXTSTYLE
.addr OUTTEXT
.addr 0 ; IRQ entry is unused
; ------------------------------------------------------------------------
.bss
ERROR: .res 1 ; Error code
MIX: .res 1 ; 4 lines of text
; ------------------------------------------------------------------------
.rodata
DEFPALETTE: .byte $00, $01, $02, $03, $04, $05, $06, $07
.byte $08, $09, $0A, $0B, $0C, $0D, $0E, $0F
TGI2COL: .byte $00, $0C, $03, $0F, $01, $09, $06, $02
.byte $04, $05, $07, $08, $0A, $0B, $0D, $0E
COL2TGI: .byte $00, $04, $07, $02, $08, $09, $06, $0A
.byte $0B, $05, $0C, $0D, $01, $0E, $0F, $03
MAXY: .byte 47, 39
; ------------------------------------------------------------------------
.code
; INIT: Changes an already installed device from text mode to graphics mode.
; Note that INIT/DONE may be called multiple times while the driver
; is loaded, while INSTALL is only called once, so any code that is needed
; to initializes variables and so on must go here. Setting palette and
; clearing the screen is not needed because this is called by the graphics
; kernel later.
; The graphics kernel will never call INIT when a graphics mode is already
; active, so there is no need to protect against that.
; Must set an error code: YES
INIT:
; Switch into graphics mode
bit $C082 ; Switch in ROM
jsr SETGR
bit MIXCLR
bit $C080 ; Switch in LC bank 2 for R/O
; Done, reset the error code
lda #TGI_ERR_OK
sta ERROR
sta MIX
; Fall through
; INSTALL routine. Is called after the driver is loaded into memory. May
; initialize anything that has to be done just once. Is probably empty
; most of the time.
; Must set an error code: NO
INSTALL:
; Fall through
; UNINSTALL routine. Is called before the driver is removed from memory. May
; clean up anything done by INSTALL but is probably empty most of the time.
; Must set an error code: NO
UNINSTALL:
; Fall through
; SETVIEWPAGE: Set the visible page. Called with the new page in A (0..n).
; The page number is already checked to be valid by the graphics kernel.
; Must set an error code: NO (will only be called if page ok)
SETVIEWPAGE:
; Fall through
; SETDRAWPAGE: Set the drawable page. Called with the new page in A (0..n).
; The page number is already checked to be valid by the graphics kernel.
; Must set an error code: NO (will only be called if page ok)
SETDRAWPAGE:
; Fall through
; 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:
; Fall through
; OUTTEXT: Output text at X/Y = ptr1/ptr2 using the current color and the
; current text style. The text to output is given as a zero terminated
; string with address in ptr3.
; Must set an error code: NO
OUTTEXT:
rts
; DONE: Will be called to switch the graphics device back into text mode.
; The graphics kernel will never call DONE when no graphics mode is active,
; so there is no need to protect against that.
; Must set an error code: NO
DONE:
bit $C082 ; Switch in ROM
jsr TEXT
jsr HOME
bit $C080 ; Switch in LC bank 2 for R/O
rts
; GETERROR: Return the error code in A and clear it.
GETERROR:
lda ERROR
ldx #TGI_ERR_OK
stx ERROR
rts
; CLEAR: Clears the screen.
; Must set an error code: NO
CLEAR:
bit $C082 ; Switch in ROM
lda COLOR ; Save current drawing color
pha
ldx MIX
ldy MAXY,x ; Max Y depends on 4 lines of text
jsr CLRSC2
pla
sta COLOR ; Restore current drawing color
bit $C080 ; Switch in LC bank 2 for R/O
rts
; SETCOLOR: Set the drawing color (in A). The new color is already checked
; to be in a valid range (0..maxcolor-1).
; Must set an error code: NO (will only be called if color ok)
SETCOLOR:
bit $C082 ; Switch in ROM
tax
lda TGI2COL,x
jsr SETCOL
bit $C080 ; Switch in LC bank 2 for R/O
rts
; CONTROL: Platform/driver specific entry point.
; Must set an error code: YES
CONTROL:
; Check data msb and code to be 0
ora ptr1+1
bne err
; Check data lsb to be [0..1]
lda ptr1
cmp #1+1
bcs err
bit $C082 ; Switch in ROM
; Switch 4 lines of text
tax
.assert MIXCLR + 1 = MIXSET, error
lda MIXCLR,x ; No BIT absolute,X available
; Save current switch setting
txa
sta MIX
bne text
; Clear 8 lines of graphics
lda COLOR ; Save current drawing color
pha
lda #39 ; Rightmost column
sta H2
ldx #40 ; First line
: txa
ldy #$00 ; Leftmost column
sty COLOR ; Black
jsr HLINE ; Preserves X
inx
cpx #47+1 ; Last line
bcc :-
pla
sta COLOR ; Restore current drawing color
bcs :+ ; Branch always
; Clear 4 lines of text
text: jsr HOME
: bit $C080 ; Switch in LC bank 2 for R/O
; Done, reset the error code
lda #TGI_ERR_OK
beq :+ ; Branch always
; Done, set the error code
err: lda #TGI_ERR_INV_ARG
: sta ERROR
rts
; SETPALETTE: Set the palette (not available with all drivers/hardware).
; A pointer to the palette is passed in ptr1. Must set an error if palettes
; are not supported
; Must set an error code: YES
SETPALETTE:
lda #TGI_ERR_INV_FUNC
sta ERROR
rts
; GETPALETTE: Return the current palette in A/X. Even drivers that cannot
; set the palette should return the default palette here, so there's no
; way for this function to fail.
; Must set an error code: NO
GETPALETTE:
; Fall through
; GETDEFPALETTE: Return the default palette for the driver in A/X. All
; drivers should return something reasonable here, even drivers that don't
; support palettes, otherwise the caller has no way to determine the colors
; of the (not changeable) palette.
; Must set an error code: NO (all drivers must have a default palette)
GETDEFPALETTE:
lda #<DEFPALETTE
ldx #>DEFPALETTE
rts
; SETPIXEL: Draw one pixel at X1/Y1 = ptr1/ptr2 with the current drawing
; color. The coordinates passed to this function are never outside the
; visible screen area, so there is no need for clipping inside this function.
; Must set an error code: NO
SETPIXEL:
bit $C082 ; Switch in ROM
ldy X1
lda Y1
jsr PLOT
bit $C080 ; Switch in LC bank 2 for R/O
rts
; GETPIXEL: Read the color value of a pixel and return it in A/X. The
; coordinates passed to this function are never outside the visible screen
; area, so there is no need for clipping inside this function.
GETPIXEL:
bit $C082 ; Switch in ROM
ldy X1
lda Y1
jsr SCRN
tax
lda COL2TGI,x
ldx #$00
bit $C080 ; Switch in LC bank 2 for R/O
rts
; BAR: Draw a filled rectangle with the corners X1/Y1, X2/Y2, where
; X1/Y1 = ptr1/ptr2 and X2/Y2 = ptr3/ptr4 using the current drawing color.
; Contrary to most other functions, the graphics kernel will sort and clip
; the coordinates before calling the driver, so on entry the following
; conditions are valid:
; X1 <= X2
; Y1 <= Y2
; (X1 >= 0) && (X1 < XRES)
; (X2 >= 0) && (X2 < XRES)
; (Y1 >= 0) && (Y1 < YRES)
; (Y2 >= 0) && (Y2 < YRES)
; Must set an error code: NO
BAR:
bit $C082 ; Switch in ROM
lda X2
sta H2
inc Y2
ldx Y1
: txa
ldy X1
jsr HLINE ; Preserves X
inx
cpx Y2
bcc :-
bit $C080 ; Switch in LC bank 2 for R/O
rts
; ------------------------------------------------------------------------
.include "../../tgi/tgidrv_line.inc"