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60d4209383
git-svn-id: svn://svn.rockbox.org/rockbox/trunk@20836 a1c6a512-1295-4272-9138-f99709370657
97 lines
3.4 KiB
C
97 lines
3.4 KiB
C
/***************************************************************************
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* __________ __ ___.
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* Open \______ \ ____ ____ | | _\_ |__ _______ ___
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* Source | _// _ \_/ ___\| |/ /| __ \ / _ \ \/ /
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* Jukebox | | ( <_> ) \___| < | \_\ ( <_> > < <
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* Firmware |____|_ /\____/ \___ >__|_ \|___ /\____/__/\_ \
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* \/ \/ \/ \/ \/
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* $Id$
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*
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* JPEG image viewer
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* Common structs and defines for plugin and core JPEG decoders
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*
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* File scrolling addition (C) 2005 Alexander Spyridakis
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* Copyright (C) 2004 Jörg Hohensohn aka [IDC]Dragon
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* Heavily borrowed from the IJG implementation (C) Thomas G. Lane
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* Small & fast downscaling IDCT (C) 2002 by Guido Vollbeding JPEGclub.org
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version 2
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* of the License, or (at your option) any later version.
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*
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* This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
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* KIND, either express or implied.
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*
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****************************************************************************/
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#ifndef _JPEG_COMMON_H
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#define _JPEG_COMMON_H
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#define HUFF_LOOKAHEAD 8 /* # of bits of lookahead */
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#define JPEG_READ_BUF_SIZE 16
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struct derived_tbl
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{
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/* Basic tables: (element [0] of each array is unused) */
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long mincode[17]; /* smallest code of length k */
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long maxcode[18]; /* largest code of length k (-1 if none) */
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/* (maxcode[17] is a sentinel to ensure huff_DECODE terminates) */
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int valptr[17]; /* huffval[] index of 1st symbol of length k */
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/* Back link to public Huffman table (needed only in slow_DECODE) */
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int* pub;
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/* Lookahead tables: indexed by the next HUFF_LOOKAHEAD bits of
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the input data stream. If the next Huffman code is no more
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than HUFF_LOOKAHEAD bits long, we can obtain its length and
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the corresponding symbol directly from these tables. */
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int look_nbits[1<<HUFF_LOOKAHEAD]; /* # bits, or 0 if too long */
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unsigned char look_sym[1<<HUFF_LOOKAHEAD]; /* symbol, or unused */
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};
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#define QUANT_TABLE_LENGTH 64
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/* for type of Huffman table */
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#define DC_LEN 28
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#define AC_LEN 178
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struct huffman_table
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{ /* length and code according to JFIF format */
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int huffmancodes_dc[DC_LEN];
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int huffmancodes_ac[AC_LEN];
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};
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struct frame_component
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{
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int ID;
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int horizontal_sampling;
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int vertical_sampling;
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int quanttable_select;
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};
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struct scan_component
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{
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int ID;
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int DC_select;
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int AC_select;
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};
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struct bitstream
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{
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unsigned long get_buffer; /* current bit-extraction buffer */
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int bits_left; /* # of unused bits in it */
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unsigned char* next_input_byte;
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unsigned char* input_end; /* upper limit +1 */
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};
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/* possible return flags for process_markers() */
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#define HUFFTAB 0x0001 /* with huffman table */
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#define QUANTTAB 0x0002 /* with quantization table */
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#define APP0_JFIF 0x0004 /* with APP0 segment following JFIF standard */
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#define FILL_FF 0x0008 /* with 0xFF padding bytes at begin/end */
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#define SOF0 0x0010 /* with SOF0-Segment */
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#define DHT 0x0020 /* with Definition of huffman tables */
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#define SOS 0x0040 /* with Start-of-Scan segment */
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#define DQT 0x0080 /* with definition of quantization table */
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#endif /* _JPEG_COMMON_H */
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