From 36c824864c02f0a3f62c8a1d365d1670835c8c96 Mon Sep 17 00:00:00 2001
From: "Christian A. Weber" <chris@gna.ch>
Date: Tue, 12 May 1992 22:26:12 +0000
Subject: Initial revision

---
 Source/DecompressBlock.S | 107 +++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 107 insertions(+)
 create mode 100644 Source/DecompressBlock.S

(limited to 'Source/DecompressBlock.S')

diff --git a/Source/DecompressBlock.S b/Source/DecompressBlock.S
new file mode 100644
index 0000000..f6c8ec5
--- /dev/null
+++ b/Source/DecompressBlock.S
@@ -0,0 +1,107 @@
+**
+**	$Id: $
+**	$Revision: $
+**
+**	$Filename: DecompressBlock.S $
+**	$Author: Christian A. Weber $
+**	$Release: $
+**	$Date: 92/05/12 22:26:30 $
+**
+**	iff.library/IFFLib_DecompressBlock
+**
+**	COPYRIGHT (C) 1987-1992 BY CHRISTIAN A. WEBER, BRUGGERWEG 2,
+**	CH-8037 ZUERICH, SWITZERLAND.  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 PER-
+**	MISSION OF THE AUTHOR. USE AT YOUR OWN RISK.
+**
+
+
+		IDNT	IFFLib_DecompressBlock
+		SECTION	text,CODE
+
+		INCLUDE	"IffLib.i"
+
+		XREF	ClearError
+		XDEF	DecompressBlockFunc
+
+
+******* iff.library/IFFLib_DecompressBlock ************************************
+*
+*    NAME
+*	IFFLib_DecompressBlock -- Decompress a memory block
+*
+*    SYNOPSIS
+*	result = IFFLib_DecompressBlock( source, destination, size, mode )
+*	                                 A0      A1           D0    D1
+*
+*	ULONG IFFLib_DecompressBlock( APTR, APTR, ULONG, ULONG )
+*
+*    FUNCTION
+*	Decompress the memory block using the appropriate Decompression mode.
+*	If the Decompressed data would become longer than the unDecompressed,
+*	an error is returned.
+*
+*    INPUTS
+*	source      - Pointer to data to decompress
+*	destination - Target address for decompression
+*	size        - Number of data bytes to decompress
+*	mode        - Compression mode. Currently, the following modes
+*	              are supported:
+*	              $$$
+*
+*    RESULTS
+*	Length of uncompressed data or 0 if an error occurred.
+*
+*    SEE ALSO
+*	IFFLib_CompressBlock()
+*
+*****************************************************************************
+
+DecompressBlockFunc:
+		tst.l	d1		; Modus == 0 ?
+		beq.b	Mode_Copy
+		subq.l	#1,d1		; Modus == 1 ?
+		beq.b	Mode_CmpByteRun1
+		moveq.l	#0,d0
+		rts
+
+*****************************************************************************
+**	Kopiermodus
+
+Mode_Copy:	movem.l	d0/a6,-(SP)
+		movea.l	ib_SysBase(a6),a6
+		JSRLIB	CopyMem
+		movem.l	(SP)+,d0/a6
+		rts
+
+*****************************************************************************
+**	CmpByteRun1 dekomprimieren
+
+Mode_CmpByteRun1:
+		move.l	d2,-(SP)
+
+1$:		moveq.l	#0,d1
+		move.b	(a0)+,d1	; D1 :  nächstes Kommando-Byte
+		bmi.b	2$		; crunched --->
+
+.CopyLoop:	move.b	(a0)+,(a1)+	; D1+1 Bytes normal kopieren
+		subq.l	#1,d0		; DEC length counter
+		dble	d1,.CopyLoop
+		bra.b	3$		; --->
+2$:
+		neg.b	d1
+		bmi.b	3$		; ~$80 (== $80) ist 'NOP'
+		move.b	(a0)+,d2	; Zu repetierender Wert
+.RepLoop:	move.b	d2,(a1)+
+		subq.l	#1,d0		; DEC ColumnCounter
+		dble	d1,.RepLoop
+3$:
+		tst.l	d0		; Linie fertig ? (Braucht's das tst??)
+		bgt.b	1$		; noch nicht ---> Loop
+
+		move.l	(SP)+,d2
+		rts
+
+		END
+
-- 
cgit v1.2.3