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