Re-factor and re-license under the libjpeg BSD-style license. Justification: the accelerated Huffman decoding optimizations in libjpeg-turbo were all developed by me as an independent developer. The structure of the inline Huffman decoding macros was originally borrowed from similar routines in the TurboJPEG/mediaLib codec, which is part of VirtualGL and TurboVNC. Thus, although the code for these macros was not copied verbatim, they were still thought to be a derivative work of TurboJPEG/mediaLib, and I assigned the copyright and license from TurboJPEG/mediaLib to them. I have re-written these routines from first principles by breaking down the libjpeg out-of-line routines. Although the new code bears algorithmic similarities to the TurboJPEG/mediaLib macros, it can now clearly be shown to be derived from the out-of-line routines and thus, in my opinion, it can no longer be considered a derivative of TurboJPEG/mediaLib. -- DRC
This commit is contained in:
DRC
122
jdhuff.c
122
jdhuff.c
@@ -2,7 +2,7 @@
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* jdhuff.c
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*
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* Copyright (C) 1991-1997, Thomas G. Lane.
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* Copyright (C) 2010, D. R. Commander.
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* Copyright (C) 2009-2011, D. R. Commander.
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* This file is part of the Independent JPEG Group's software.
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* For conditions of distribution and use, see the accompanying README file.
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*
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@@ -15,21 +15,6 @@
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* storage only upon successful completion of an MCU.
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*/
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/* Performance enhancements:
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* Copyright (C)2007 Sun Microsystems, Inc.
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* Copyright (C)2009-2010 D. R. Commander
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*
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* This library is free software and may be redistributed and/or modified under
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* the terms of the wxWindows Library License, Version 3.1 or (at your option)
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* any later version. The full license is in the LICENSE.txt file included
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* with this distribution.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* wxWindows Library License for more details.
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*/
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#define JPEG_INTERNALS
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#include "jinclude.h"
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#include "jpeglib.h"
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@@ -407,6 +392,50 @@ jpeg_fill_bit_buffer (bitread_working_state * state,
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}
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/* Macro version of the above, which performs much better but does not
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handle markers. We have to hand off any blocks with markers to the
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slower routines. */
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#define GET_BYTE \
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{ \
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register int c0, c1; \
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c0 = GETJOCTET(*buffer++); \
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c1 = GETJOCTET(*buffer); \
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/* Pre-execute most common case */ \
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get_buffer = (get_buffer << 8) | c0; \
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bits_left += 8; \
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if (c0 == 0xFF) { \
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/* Pre-execute case of FF/00, which represents an FF data byte */ \
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buffer++; \
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if (c1 != 0) { \
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/* Oops, it's actually a marker indicating end of compressed data. */ \
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cinfo->unread_marker = c1; \
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/* Back out pre-execution and fill the buffer with zero bits */ \
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buffer -= 2; \
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get_buffer &= ~0xFF; \
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} \
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} \
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}
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#if __WORDSIZE == 64 || defined(_WIN64)
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/* Pre-fetch 48 bytes, because the holding register is 64-bit */
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#define FILL_BIT_BUFFER_FAST \
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if (bits_left < 16) { \
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GET_BYTE GET_BYTE GET_BYTE GET_BYTE GET_BYTE GET_BYTE \
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}
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#else
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/* Pre-fetch 16 bytes, because the holding register is 32-bit */
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#define FILL_BIT_BUFFER_FAST \
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if (bits_left < 16) { \
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GET_BYTE GET_BYTE \
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}
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#endif
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/*
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* Out-of-line code for Huffman code decoding.
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* See jdhuff.h for info about usage.
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@@ -612,61 +641,6 @@ decode_mcu_slow (j_decompress_ptr cinfo, JBLOCKROW *MCU_data)
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}
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/***************************************************************/
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#define ADD_BYTE { \
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int val0 = *(buffer++); \
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int val1 = *(buffer); \
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\
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bits_left += 8; \
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get_buffer = (get_buffer << 8) | (val0); \
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if (val0 == 0xFF) { \
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buffer++; \
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if (val1 != 0) { \
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cinfo->unread_marker = val1; \
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buffer -= 2; \
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get_buffer &= ~0xFF; \
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} \
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} \
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}
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/***************************************************************/
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#if __WORDSIZE == 64 || defined(_WIN64)
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#define ENSURE_SHORT \
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if (bits_left < 16) { \
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ADD_BYTE ADD_BYTE ADD_BYTE ADD_BYTE ADD_BYTE ADD_BYTE \
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}
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#else
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#define ENSURE_SHORT if (bits_left < 16) { ADD_BYTE ADD_BYTE }
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#endif
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/***************************************************************/
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#define HUFF_DECODE_FAST(symbol, size, htbl) { \
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ENSURE_SHORT \
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symbol = PEEK_BITS(HUFF_LOOKAHEAD); \
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symbol = htbl->lookup[symbol]; \
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size = symbol >> 8; \
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bits_left -= size; \
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symbol = symbol & ((1 << HUFF_LOOKAHEAD) - 1); \
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if (size == HUFF_LOOKAHEAD + 1) { \
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symbol = (get_buffer >> bits_left) & ((1 << (size)) - 1); \
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while (symbol > htbl->maxcode[size]) { \
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symbol <<= 1; \
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symbol |= GET_BITS(1); \
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size++; \
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} \
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symbol = htbl->pub->huffval[ (int) (symbol + htbl->valoffset[size]) & 0xFF ]; \
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} \
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}
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/***************************************************************/
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LOCAL(boolean)
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decode_mcu_fast (j_decompress_ptr cinfo, JBLOCKROW *MCU_data)
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{
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@@ -690,7 +664,7 @@ decode_mcu_fast (j_decompress_ptr cinfo, JBLOCKROW *MCU_data)
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HUFF_DECODE_FAST(s, l, dctbl);
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if (s) {
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ENSURE_SHORT
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FILL_BIT_BUFFER_FAST
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r = GET_BITS(s);
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s = HUFF_EXTEND(r, s);
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}
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@@ -711,7 +685,7 @@ decode_mcu_fast (j_decompress_ptr cinfo, JBLOCKROW *MCU_data)
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if (s) {
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k += r;
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ENSURE_SHORT
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FILL_BIT_BUFFER_FAST
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r = GET_BITS(s);
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s = HUFF_EXTEND(r, s);
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(*block)[jpeg_natural_order[k]] = (JCOEF) s;
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@@ -730,7 +704,7 @@ decode_mcu_fast (j_decompress_ptr cinfo, JBLOCKROW *MCU_data)
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if (s) {
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k += r;
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ENSURE_SHORT
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FILL_BIT_BUFFER_FAST
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DROP_BITS(s);
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} else {
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if (r != 15) break;
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22
jdhuff.h
22
jdhuff.h
@@ -2,7 +2,7 @@
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* jdhuff.h
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*
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* Copyright (C) 1991-1997, Thomas G. Lane.
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* Copyright (C) 2010, D. R. Commander.
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* Copyright (C) 2010-2011, D. R. Commander.
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* This file is part of the Independent JPEG Group's software.
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* For conditions of distribution and use, see the accompanying README file.
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*
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@@ -208,6 +208,26 @@ slowlabel: \
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} \
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}
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#define HUFF_DECODE_FAST(s,nb,htbl) \
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FILL_BIT_BUFFER_FAST; \
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s = PEEK_BITS(HUFF_LOOKAHEAD); \
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s = htbl->lookup[s]; \
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nb = s >> HUFF_LOOKAHEAD; \
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/* Pre-execute the common case of nb <= HUFF_LOOKAHEAD */ \
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DROP_BITS(nb); \
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s = s & ((1 << HUFF_LOOKAHEAD) - 1); \
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if (nb > HUFF_LOOKAHEAD) { \
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/* Equivalent of jpeg_huff_decode() */ \
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/* Don't use GET_BITS() here because we don't want to modify bits_left */ \
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s = (get_buffer >> bits_left) & ((1 << (nb)) - 1); \
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while (s > htbl->maxcode[nb]) { \
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s <<= 1; \
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s |= GET_BITS(1); \
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nb++; \
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} \
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s = htbl->pub->huffval[ (int) (s + htbl->valoffset[nb]) & 0xFF ]; \
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}
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/* Out-of-line case for Huffman code fetching */
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EXTERN(int) jpeg_huff_decode
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JPP((bitread_working_state * state, register bit_buf_type get_buffer,
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