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/* $Xorg: dpackbits.c,v 1.4 2000/08/17 19:46:40 cpqbld Exp $ */
/*
* Copyright (c) 1988, 1989, 1990, 1991, 1992 Sam Leffler
* Copyright (c) 1991, 1992 Silicon Graphics, Inc.
*
* Permission to use, copy, modify, distribute, and sell this software and
* its documentation for any purpose is hereby granted without fee, provided
* that (i) the above copyright notices and this permission notice appear in
* all copies of the software and related documentation, and (ii) the names of
* Sam Leffler and Silicon Graphics may not be used in any advertising or
* publicity relating to the software without the specific, prior written
* permission of Sam Leffler and Silicon Graphics.
*
* THE SOFTWARE IS PROVIDED "AS-IS" AND WITHOUT WARRANTY OF ANY KIND,
* EXPRESS, IMPLIED OR OTHERWISE, INCLUDING WITHOUT LIMITATION, ANY
* WARRANTY OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
*
* IN NO EVENT SHALL SAM LEFFLER OR SILICON GRAPHICS BE LIABLE FOR
* ANY SPECIAL, INCIDENTAL, INDIRECT OR CONSEQUENTIAL DAMAGES OF ANY KIND,
* OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS,
* WHETHER OR NOT ADVISED OF THE POSSIBILITY OF DAMAGE, AND ON ANY THEORY OF
* LIABILITY, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE
* OF THIS SOFTWARE.
*/
/* $XFree86: xc/lib/lbxutil/image/dpackbits.c,v 1.4 2001/01/17 19:43:35 dawes Exp $ */
#include <X11/Xos.h>
#include <X11/Xfuncproto.h>
#include "lbximage.h"
/*
* -------------------------------------------------------------------------
* PackBits decoding for 8 bit color images
* -------------------------------------------------------------------------
*/
static void
DecodePackBits (char **inbuf,
int numPixels,
char *outbuf)
{
register char *inptr = *inbuf;
register int n, b;
while (numPixels > 0)
{
n = (int) *inptr++;
/* Watch out for compilers that don't sign extend chars... */
if (n >= 128)
n -= 256;
if (n < 0)
{
/* replicate next byte -n+1 times */
if (n == -128) /* nop */
continue;
n = -n + 1;
numPixels -= n;
for (b = *inptr++; n-- > 0;)
*outbuf++ = b;
}
else
{
/* copy next n+1 bytes literally */
memcpy (outbuf, inptr, ++n);
outbuf += n; numPixels -= n;
inptr += n;
}
}
*inbuf = inptr;
}
int
LbxImageDecodePackBits (char *inbuf,
char *outbuf,
int num_scan_lines,
int scan_line_size)
{
char *outbuf_start = outbuf;
int padded_scan_line_size = (scan_line_size % 4) ?
scan_line_size + (4 - scan_line_size % 4) : scan_line_size;
while (num_scan_lines > 0)
{
DecodePackBits (&inbuf, scan_line_size, outbuf);
outbuf += padded_scan_line_size;
num_scan_lines--;
}
return (outbuf - outbuf_start);
}
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