**
**  $Id: MovieDecode.a,v 1.1 93/05/24 14:33:22 chris Exp $
**  $Revision: 1.1 $
**
**  $Filename: MovieDecode/MovieDecode.a $
**  $Author: chris $
**  $Release: $
**  $Date: 93/05/24 14:33:22 $
**
**  Frame decoder for Sculpt/Animate MOVIE Format
**
**  Author: Christian A. Weber, Bruggerweg 2, CH-8037 Zürich, Switzerland
**  E-mail: chris@mighty.adsp.sub.org  -or-  weber@amiga.physik.unizh.ch
**
**  COPYRIGHT © 1990-1993 BY CHRISTIAN A. WEBER.  ALL RIGHTS RESERVED.
**  NO PART OF THIS SOFTWARE MAY BE COPIED, REPRODUCED, OR TRANSMITTED
**  IN ANY FORM OR BY ANY MEANS,  WITHOUT THE PRIOR WRITTEN PERMISSION
**  OF THE AUTHOR. NO WARRANTY. USE AT YOUR OWN RISK.
**
**  Note: I use the Devpac Assembler, but it should work with other
**        Assemblers too. The code is pure and reentrant. V37 or newer
**        is required.
**

		OPT	O+,OW-		; Devpac: Optimize without warnings

		IDNT	JDecode
		SECTION	text,CODE

		INCLUDE	"exec/types.i"
		INCLUDE	"exec/memory.i"
		INCLUDE	"exec/macros.i"
		INCLUDE	"graphics/gfx.i"

		XDEF	_InitJDecoder,_FreeJDecoder,_ModifyJFrame


* Memory used for the automatically generated player code

MEMSIZE		EQU	32000


* Structure of an entry of "MoveTable"

   STRUCTURE TabEntry,0
	APTR	dec_Template	; Pointer to template
	WORD	dec_TempSize	; Size of template
	LABEL	dec_SIZEOF


* For my ego :-)

	dc.b	"J-Type ANIM Decoder V2.0 by Christian A. Weber",10,0


******* MovieDecode/InitJDecoder ********************************************
*
*    NAME
*	InitJDecoder -- Initialize the player code for a given animation
*
*    SYNOPSIS
*	handle = InitJDecoder(animtype)
*	D0                    D0
*
*	APTR InitJDecoder(ULONG animtype);
*
*    FUNCTION
*	Initializes the movie player for a given animation type. This is
*	typically called once after loading the animation. After playing,
*	FreeJDecoder() should be called (with the handle this function
*	returns) to free any resources allocated by this function.
*
*    INPUTS
*	animtype - Bits 0 to 7: Number of bitplanes (1..6)
*	           Bit 16: mode 0 = "Move" (loop), 1 = "EOR" (ping-pong)
*
*    RESULT
*	Non-zero if everything was OK, NULL if no memory or bad animtype.
*
*    BUGS
*
*    SEE ALSO
*	FreeJDecoder()
*
*****************************************************************************

_InitJDecoder:	movem.l	d2-d7/a2-a6,-(SP)
		move.l	d0,d7			; D7: type & depth

	*** Allocate memory for the player code

		move.l	#MEMSIZE,d0
		moveq.l	#MEMF_ANY,d1
		movea.l	(4).W,a6
		JSRLIB	AllocVec
		tst.l	d0			; Memory OK ?
		beq	initerror		; no --->
		movea.l	d0,a2			; A2: Player code buffer

	*** Copy header of the player code into the allocated buffer

		movea.l	a2,a3			; Destination
		lea	Code(PC),a0		; Source
		moveq.l	#(CodeEnd-Code)/2-1,d0	; Size (words) - 1
1$:		move.w	(a0)+,(a3)+
		dbf	d0,1$

	*** Create jump table for the different anim operands

mktab:		movea.l	a3,a4
		moveq	#3,d0			; 4 types: Byte/Word/Long/Quad
		moveq	#Error-CodeEnd-2,d2	; D2 :  BRA to Error-Offset
1$:		moveq	#32,d1			; 33 entries per table
		move.l	#$4EFB1002,(a4)+	; JMP 02(PC,D1.W)
		subq.w	#4,d2			; correct offset (negative)
2$:		move.w	#$6000,(a4)+		; BRA.W
		move.w	d2,(a4)+
		subq.w	#4,d2			; correct offset (negative)
		dbf	d1,2$
		dbf	d0,1$

	*** Create decoding routines for the different anim operands

mkroutines:	lea	MoveTable(PC),a1
		bclr	#16,d7			; EOR (reversible) mode ?
		beq.b	1$			; no --->
		lea	EORTable(PC),a1
1$:
		addq.l	#2,a3			; BRA offsets of the jump table
		moveq	#3,d0			; 4 types: Byte/Word/Long/Quad
.Loop1:		moveq	#0,d1			; 10 routines: 1-8,16,32 lines
		addq.l	#4+4,a3			; Skip JMP and first BRA

.Loop2:		move.w	d1,d2			; Number of repetitions-1
		cmpi.w	#8,d1
		bne.b	2$
		moveq	#16-1,d2
		lea	7*4(a3),a3		; Skip vectors for 9 to 15
2$:		cmpi.w	#9,d1
		bne.b	3$
		moveq	#32-1,d2
		lea	15*4(a3),a3		; Skip vectors for 17 to 31
3$:		move.w	d2,d3
		addq.w	#1,d3			; D3: number of repetitions

		movea.l	a4,a5			; A5: Start of actual routine
		move.w	#$3018,(a4)+		; MOVE.W (A0)+,D0
.Loop3:		movea.l	dec_Template(a1),a0	; Template
		move.w	dec_TempSize(a1),d4	; Size of template in WORDs
		mulu.w	d7,d4			; * number of bitplanes
		bra.b	.Dbf4			; For dbf
.Loop4:		move.w	(a0)+,(a4)+		; Copy the template
.Dbf4:		dbf	d4,.Loop4
		tst.w	d2			; Is this the last one ?
		beq.b	.NoAdd			; yes ---> don't generate ADD ins
		move.w	#$D047,(a4)+		; ADD.W D7,D0
.NoAdd:
		dbf	d2,.Loop3

	*** If we're in BYTE mode with an odd number of planes we have
	*** to insert an ADDQ.L #1,A0 instruction to word-align the
	*** delta data.

		cmpi.b	#3,d0			; BYTE mode ?
		bne.b	6$			; no ---> no ADD required
		btst	#0,d7			; Even number of bitplanes ?
		beq.b	6$			; yes ---> no ADD required
		btst	#0,d3			; Even number of repetitions ?
		beq.b	6$			; yes ---> no ADD required
		move.w	#$5288,(a4)+		; ADDQ.L #1,A0
6$:
	*** Insert the start of this routine into the BRA.W table

		move.l	a4,d4			; Jump Destination: before the DBF
		sub.l	a3,d4			; minus table offset
		move.w	d4,(a3)			; gives offset of BRA
		addq.w	#4,a3			; Pointer to next BRA

		move.w	#$51CE,(a4)+		; DBF D6,
		move.l	a5,d4			; Branch destination: Start of routine
		sub.l	a4,d4			; minus actual address
		move.w	d4,(a4)+		; gives offset

		move.w	#$6000,(a4)+		; BRA.W
		move.l	a2,d4			; Branch destination: MainLoop
		sub.l	a4,d4			; minus actual address
		move.w	d4,(a4)+		; gives offset

		addq.w	#1,d1			; increment number of repetitions
		cmpi.w	#10,d1
		blt.b	.Loop2

		addq.l	#dec_SIZEOF,a1		; Next template
		dbf	d0,.Loop1

	*** Since we created some code, we have to clear the I-cache

		JSRLIB	CacheClearU		; A6 is still holding ExecBase

		move.l	a2,d0			; Result: handle
initerror:
		movem.l	(SP)+,d2-d7/a2-a6
		rts


******* MovieDecode/FreeJDecoder ********************************************
*
*    NAME
*	FreeJDecoder -- Free the player code for an animation
*
*    SYNOPSIS
*	FreeJDecoder(handle)
*	D0           A0
*
*	VOID FreeJDecoder(APTR handle);
*
*    FUNCTION
*	Frees all resources which were allocated by InitJDecoder().
*	This is typically called once after playing an animation.
*
*    INPUTS
*	hande - result from InitJDecoder() ONLY!
*
*    RESULT
*	none
*
*    BUGS
*
*    SEE ALSO
*	InitJDecoder()
*
*****************************************************************************

_FreeJDecoder:	move.l	a6,-(SP)

	*** Free the memory we allocated in InitJDecoder()

		movea.l	a0,a1
		movea.l	(4).W,a6
		JSRLIB	FreeVec

		movea.l	(SP)+,a6
		rts


******* MovieDecode/ModifyJFrame ********************************************
*
*    NAME
*	ModifyJFrame -- Apply delta data on an animation frame
*
*    SYNOPSIS
*	success = ModifyJFrame( deltas, bitmap, handle )
*	D0		        A0      A1      A2
*
*	BOOL ModifyJFrame( APTR, struct BitMap *, APTR );
*
*    FUNCTION
*	Generates a new animation frame by changing the frame before the
*	currently displayed frame (for double-buffering, as usual).
*
*    INPUTS
*	deltas - pointer to the actual DLTA chunk data
*	bitmap - BitMap to render into
*	handle - player handle, from InitJDecoder()
*
*    RESULT
*	Non-zero if everything was OK, FALSE if an error occurred.
*
*    BUGS
*
*    SEE ALSO
*	InitJDecoder(), FreeJDecoder()
*
*****************************************************************************

_ModifyJFrame:	movem.l	d2-d7/a2-a6,-(SP)

		move.w	bm_BytesPerRow(a1),d7	; d7 :  BytesPerRow
		move.l	a2,-(SP)		; Push address of player code
		movem.l	bm_Planes(a1),a1-a6	; A1-A6: plane pointers
		moveq.l	#0,d0			; Clear bitplane index pointer
		rts				; ---> Do the code

	*** The following code fragment will be copied to the beginning
	*** of the player code. It will be followed by the decoder
	*** routines for the particular mode and bitplane depth.

Code:
MainLoop:	move.w	(a0)+,d0		; Number of bytes per entry
		addq.l	#2,a0			; Skip type: 0=Move, 1=EOR
		move.w	(a0)+,d1		; Number of rows of this width
		cmpi.w	#32,d1			; More than 32 ?
		bhi.b	End			; yes ---> we can't handle this
		lsl.w	#2,d1			; Adjust for table index
		subq.w	#1,d0			; CODE 1:  1 Byte ?
		beq.b	DoBytes			; yep --->
		subq.w	#1,d0			; CODE 2: >1 Byte ?
		bne.b	End			; no ---> finished

		move.w	(a0)+,d0		; Number of bytes per entry
		move.w	(a0)+,d6		; Number of n-rows entries
		subq.w	#4,d0
		beq	DoBytes+68*4+2		; 4 Bytes --->
		bcc	DoBytes+102*4+2		; 6 Bytes ---> (bcc == bhs)
		bra	DoBytes+34*4+2		; 2 Bytes --->

Error:		moveq	#0,d0			; Result: Error
		bra.b	Exit
End:		moveq	#1,d0			; Result: Success
Exit:		movem.l	(SP)+,d2-d7/a2-a6
		rts

DoBytes:	move.w	(a0)+,d6		; Number of n-rows-entries
CodeEnd:

	*** Here are the templates for the various operations.
	*** No code is generated for unused bitplanes.

MoveByteTemplate:
		move.b	(a0)+,0(a1,d0.L)
		move.b	(a0)+,0(a2,d0.L)
		move.b	(a0)+,0(a3,d0.L)
		move.b	(a0)+,0(a4,d0.L)
		move.b	(a0)+,0(a5,d0.L)
		move.b	(a0)+,0(a6,d0.L)
MoveByteTemplateEnd:

MoveWordTemplate:
		move.w	(a0)+,0(a1,d0.L)
		move.w	(a0)+,0(a2,d0.L)
		move.w	(a0)+,0(a3,d0.L)
		move.w	(a0)+,0(a4,d0.L)
		move.w	(a0)+,0(a5,d0.L)
		move.w	(a0)+,0(a6,d0.L)
MoveWordTemplateEnd:

MoveLongTemplate:
		move.l	(a0)+,0(a1,d0.L)
		move.l	(a0)+,0(a2,d0.L)
		move.l	(a0)+,0(a3,d0.L)
		move.l	(a0)+,0(a4,d0.L)
		move.l	(a0)+,0(a5,d0.L)
		move.l	(a0)+,0(a6,d0.L)
MoveLongTemplateEnd:

MoveQuadTemplate:
		move.l	(a0)+,0(a1,d0.L)
		move.w	(a0)+,4(a1,d0.L)
		move.l	(a0)+,0(a2,d0.L)
		move.w	(a0)+,4(a2,d0.L)
		move.l	(a0)+,0(a3,d0.L)
		move.w	(a0)+,4(a3,d0.L)
		move.l	(a0)+,0(a4,d0.L)
		move.w	(a0)+,4(a4,d0.L)
		move.l	(a0)+,0(a5,d0.L)
		move.w	(a0)+,4(a5,d0.L)
		move.l	(a0)+,0(a6,d0.L)
		move.w	(a0)+,4(a6,d0.L)
MoveQuadTemplateEnd:

EORByteTemplate:
		move.b	(a0)+,d1
		eor.b	d1,0(a1,d0.L)
		move.b	(a0)+,d1
		eor.b	d1,0(a2,d0.L)
		move.b	(a0)+,d1
		eor.b	d1,0(a3,d0.L)
		move.b	(a0)+,d1
		eor.b	d1,0(a4,d0.L)
		move.b	(a0)+,d1
		eor.b	d1,0(a5,d0.L)
		move.b	(a0)+,d1
		eor.b	d1,0(a6,d0.L)
EORByteTemplateEnd:

EORWordTemplate:
		move.w	(a0)+,d1
		eor.w	d1,0(a1,d0.L)
		move.w	(a0)+,d1
		eor.w	d1,0(a2,d0.L)
		move.w	(a0)+,d1
		eor.w	d1,0(a3,d0.L)
		move.w	(a0)+,d1
		eor.w	d1,0(a4,d0.L)
		move.w	(a0)+,d1
		eor.w	d1,0(a5,d0.L)
		move.w	(a0)+,d1
		eor.w	d1,0(a6,d0.L)
EORWordTemplateEnd:

EORLongTemplate:
		move.l	(a0)+,d1
		eor.l	d1,0(a1,d0.L)
		move.l	(a0)+,d1
		eor.l	d1,0(a2,d0.L)
		move.l	(a0)+,d1
		eor.l	d1,0(a3,d0.L)
		move.l	(a0)+,d1
		eor.l	d1,0(a4,d0.L)
		move.l	(a0)+,d1
		eor.l	d1,0(a5,d0.L)
		move.l	(a0)+,d1
		eor.l	d1,0(a6,d0.L)
EORLongTemplateEnd:

EORQuadTemplate:
		move.l	(a0)+,d1
		eor.l	d1,0(a1,d0.L)
		move.w	(a0)+,d1
		eor.w	d1,4(a1,d0.L)
		move.l	(a0)+,d1
		eor.l	d1,0(a2,d0.L)
		move.w	(a0)+,d1
		eor.w	d1,4(a2,d0.L)
		move.l	(a0)+,d1
		eor.l	d1,0(a3,d0.L)
		move.w	(a0)+,d1
		eor.w	d1,4(a3,d0.L)
		move.l	(a0)+,d1
		eor.l	d1,0(a4,d0.L)
		move.w	(a0)+,d1
		eor.w	d1,4(a4,d0.L)
		move.l	(a0)+,d1
		eor.l	d1,0(a5,d0.L)
		move.w	(a0)+,d1
		eor.w	d1,4(a5,d0.L)
		move.l	(a0)+,d1
		eor.l	d1,0(a6,d0.L)
		move.w	(a0)+,d1
		eor.w	d1,4(a6,d0.L)
EORQuadTemplateEnd:

MoveTable:	dc.l	MoveByteTemplate
		dc.w	(MoveByteTemplateEnd-MoveByteTemplate)/2/6
		dc.l	MoveWordTemplate
		dc.w	(MoveWordTemplateEnd-MoveWordTemplate)/2/6
		dc.l	MoveLongTemplate
		dc.w	(MoveLongTemplateEnd-MoveLongTemplate)/2/6
		dc.l	MoveQuadTemplate
		dc.w	(MoveQuadTemplateEnd-MoveQuadTemplate)/2/6
		dc.l	$43485721
EORTable:	dc.l	EORByteTemplate
		dc.w	(EORByteTemplateEnd-EORByteTemplate)/2/6
		dc.l	EORWordTemplate
		dc.w	(EORWordTemplateEnd-EORWordTemplate)/2/6
		dc.l	EORLongTemplate
		dc.w	(EORLongTemplateEnd-EORLongTemplate)/2/6
		dc.l	EORQuadTemplate
		dc.w	(EORQuadTemplateEnd-EORQuadTemplate)/2/6


	*** That's all folks!


		END