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93 lines
1.5 KiB
C
93 lines
1.5 KiB
C
/*
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* The Python Imaging Library.
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* $Id$
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*
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* decoder for PackBits image data.
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*
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* history:
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* 96-04-19 fl Created
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*
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* Copyright (c) Fredrik Lundh 1996.
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* Copyright (c) Secret Labs AB 1997.
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*
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* See the README file for information on usage and redistribution.
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*/
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#include "Imaging.h"
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int
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ImagingPackbitsDecode(Imaging im, ImagingCodecState state,
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UINT8* buf, int bytes)
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{
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UINT8 n;
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UINT8* ptr;
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int i;
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ptr = buf;
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for (;;) {
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if (bytes < 1)
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return ptr - buf;
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if (ptr[0] & 0x80) {
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if (ptr[0] == 0x80) {
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/* Nop */
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ptr++; bytes--;
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continue;
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}
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/* Run */
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if (bytes < 2)
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return ptr - buf;
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for (n = 257 - ptr[0]; n > 0; n--) {
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if (state->x >= state->bytes) {
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/* state->errcode = IMAGING_CODEC_OVERRUN; */
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break;
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}
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state->buffer[state->x++] = ptr[1];
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}
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ptr += 2; bytes -= 2;
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} else {
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/* Literal */
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n = ptr[0]+2;
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if (bytes < n)
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return ptr - buf;
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for (i = 1; i < n; i++) {
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if (state->x >= state->bytes) {
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/* state->errcode = IMAGING_CODEC_OVERRUN; */
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break;
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}
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state->buffer[state->x++] = ptr[i];
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}
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ptr += n; bytes -= n;
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}
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if (state->x >= state->bytes) {
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/* Got a full line, unpack it */
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state->shuffle((UINT8*) im->image[state->y + state->yoff] +
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state->xoff * im->pixelsize, state->buffer,
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state->xsize);
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state->x = 0;
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if (++state->y >= state->ysize) {
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/* End of file (errcode = 0) */
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return -1;
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}
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}
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}
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}
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