;
; Graphics driver for the 240x200x2 mode on the Atmos
;
; Stefan Haubenthal <polluks@sdf.lonestar.org>
;

	.include	"zeropage.inc"

	.include	"tgi-kernel.inc"
	.include	"tgi-mode.inc"
	.include	"tgi-error.inc"
	.include	"atmos.inc"

	.macpack	generic

; ------------------------------------------------------------------------
; Header. Includes jump table and constants.

.segment	"JUMPTABLE"

; 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	240			; X resolution
	.word	200			; Y resolution
	.byte	2			; Number of drawing colors
	.byte	1			; Number of screens available
xsize:	.byte	6			; System font X size
	.byte	8			; System font Y size
	.res	4, $00			; Reserved for future extensions

; Next comes the jump table. Currently 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   _CIRCLE
       	.addr   TEXTSTYLE
       	.addr   OUTTEXT
        .addr   0                       ; IRQ entry is unused

; ------------------------------------------------------------------------
; Data.

; Variables mapped to the zero page segment variables. Some of these are
; used for passing parameters to the driver.

X1		= ptr1
Y1		= ptr2
X2		= ptr3
Y2		= ptr4
RADIUS		= tmp1

; Absolute variables used in the code

.bss

ERROR:		.res	1	; Error code
MODE:		.res	1	; Graphics mode

; Constants and tables
PARAM1		= $2E1
PARAM2		= $2E3
PARAM3		= $2E5
TEXT		= $EC21
HIRES		= $EC33
CURSET		= $F0C8
CURMOV		= $F0FD
DRAW		= $F110
CHAR		= $F12D
POINT		= $F1C8
PAPER		= $F204
INK		= $F210
CIRCLE		= $F37F

.rodata

DEFPALETTE:	.byte	$00, $07

.code

; ------------------------------------------------------------------------
; 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:

; ------------------------------------------------------------------------
; 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:
	rts

; ------------------------------------------------------------------------
; 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

	jsr	HIRES

; Done, reset the error code

	lda	#TGI_ERR_OK
	sta	ERROR
	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		= TEXT

; ------------------------------------------------------------------------
; GETERROR: Return the error code in A and clear it.

GETERROR:
	ldx	#TGI_ERR_OK
	lda	ERROR
	stx	ERROR
	rts

; ------------------------------------------------------------------------
; CONTROL: Platform/driver specific entry point.
;
; Must set an error code: YES
;

CONTROL:
	sta	$213
	lda	#TGI_ERR_OK
	sta	ERROR
	rts

; ------------------------------------------------------------------------
; CLEAR: Clears the screen.
;
; Must set an error code: NO
;

CLEAR		= HIRES

; ------------------------------------------------------------------------
; 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:

; ------------------------------------------------------------------------
; 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:
	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:
	sta	MODE
	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:
	ldy	#0
	lda	(ptr1),y
	sta	PARAM1
	jsr	PAPER
	ldy	#1
	lda	(ptr1),y
	sta	PARAM1
	jsr	INK
	lda	#TGI_ERR_OK
	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:

; ------------------------------------------------------------------------
; 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:
	lda	MODE
mymode:	sta	PARAM3
	lda	X1
	sta	PARAM1
	lda	Y1
	sta	PARAM2
	lda	#0
	sta	PARAM1+1
	sta	PARAM2+1
	jmp	CURSET

; ------------------------------------------------------------------------
; 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:
	lda	X1
	sta	PARAM1
	lda	Y1
	sta	PARAM2
	lda	#0
	sta	PARAM1+1
	sta	PARAM2+1
	jsr	POINT
	lda	PARAM1
	and	#%00000001
	ldx	#0
	rts

; ------------------------------------------------------------------------
; LINE: Draw a line from X1/Y1 to X2/Y2, where X1/Y1 = ptr1/ptr2 and
; X2/Y2 = ptr3/ptr4 using the current drawing color.
;
; Must set an error code: NO
;

LINE:
	jsr	SETPIXEL
	lda	X2
	sub	X1
	sta	PARAM1
	lda	X2+1
	sbc	X1+1
	sta	PARAM1+1
	lda	Y2
	sub	Y1
	sta	PARAM2
	lda	Y2+1
	sbc	Y1+1
	sta	PARAM2+1
	lda	MODE
	sta	PARAM3
	jmp	DRAW

; ------------------------------------------------------------------------
; BAR: Draw a filled rectangle with the corners X1/Y1, X2/Y2, where
; X1/Y1 = ptr1/ptr2 and X2/Y2 = ptr3/ptr4 using the current drawing color.
; Contrary to most other functions, the graphics kernel will sort and clip
; the coordinates before calling the driver, so on entry the following
; conditions are valid:
;	X1 <= X2
;	Y1 <= Y2
;	(X1 >= 0) && (X1 < XRES)
;	(X2 >= 0) && (X2 < XRES)
;	(Y1 >= 0) && (Y1 < YRES)
;	(Y2 >= 0) && (Y2 < YRES)
;
; Must set an error code: NO
;

BAR:
	inc	Y2
@L1:	lda	Y2
	pha
  	lda	Y1
	sta	Y2
	jsr	LINE
	pla
	sta	Y2
	inc	Y1
	cmp	Y1
	bne	@L1
	rts

; ------------------------------------------------------------------------
; CIRCLE: Draw a circle around the center X1/Y1 (= ptr1/ptr2) with the
; radius in tmp1 and the current drawing color.
;
; Must set an error code: NO
;

_CIRCLE:
	lda	#3
	jsr	mymode
	lda	RADIUS
	sta	PARAM1
	lda	MODE
	sta	PARAM2
	jmp	CIRCLE

; ------------------------------------------------------------------------
; 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:
	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:
	lda	X1
	sta	PARAM1
	lda	Y1
	sta	PARAM2
	lda	#3
	sta	PARAM3
	jsr	CURSET

	ldy	#0
@next:	lda	(ptr3),y
	beq	@end
	sta	PARAM1
	lda	#0
	sta	PARAM2
	lda	MODE
	sta	PARAM3
	tya
	pha
	jsr	CHAR
	lda	xsize
	sta	PARAM1
	lda	#0
	sta	PARAM2
	lda	#3
	sta	PARAM3
	jsr	CURMOV
	pla
	tay
	iny
	bne	@next
@end:	rts
