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/***************************************************************************
* __________ __ ___.
* Open \______ \ ____ ____ | | _\_ |__ _______ ___
* Source | _// _ \_/ ___\| |/ /| __ \ / _ \ \/ /
* Jukebox | | ( <_> ) \___| < | \_\ ( <_> > < <
* Firmware |____|_ /\____/ \___ >__|_ \|___ /\____/__/\_ \
* \/ \/ \/ \/ \/
* $Id$
*
* JPEG image viewer
* (This is a real mess if it has to be coded in one single C file)
*
* File scrolling addition (C) 2005 Alexander Spyridakis
* Copyright (C) 2004 Jörg Hohensohn aka [IDC]Dragon
* Heavily borrowed from the IJG implementation (C) Thomas G. Lane
* Small & fast downscaling IDCT (C) 2002 by Guido Vollbeding JPEGclub.org
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
*
* This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
* KIND, either express or implied.
*
****************************************************************************/
#ifndef _JPEG_JPEG_DECODER_H
#define _JPEG_JPEG_DECODER_H
#define HUFF_LOOKAHEAD 8 /* # of bits of lookahead */
struct derived_tbl
{
/* Basic tables: (element [0] of each array is unused) */
long mincode[17]; /* smallest code of length k */
long maxcode[18]; /* largest code of length k (-1 if none) */
/* (maxcode[17] is a sentinel to ensure huff_DECODE terminates) */
int valptr[17]; /* huffval[] index of 1st symbol of length k */
/* Back link to public Huffman table (needed only in slow_DECODE) */
int* pub;
/* Lookahead tables: indexed by the next HUFF_LOOKAHEAD bits of
the input data stream. If the next Huffman code is no more
than HUFF_LOOKAHEAD bits long, we can obtain its length and
the corresponding symbol directly from these tables. */
int look_nbits[1<<HUFF_LOOKAHEAD]; /* # bits, or 0 if too long */
unsigned char look_sym[1<<HUFF_LOOKAHEAD]; /* symbol, or unused */
};
#define QUANT_TABLE_LENGTH 64
/* for type of Huffman table */
#define DC_LEN 28
#define AC_LEN 178
struct huffman_table
{ /* length and code according to JFIF format */
int huffmancodes_dc[DC_LEN];
int huffmancodes_ac[AC_LEN];
};
struct frame_component
{
int ID;
int horizontal_sampling;
int vertical_sampling;
int quanttable_select;
};
struct scan_component
{
int ID;
int DC_select;
int AC_select;
};
struct bitstream
{
unsigned long get_buffer; /* current bit-extraction buffer */
int bits_left; /* # of unused bits in it */
unsigned char* next_input_byte;
unsigned char* input_end; /* upper limit +1 */
};
struct jpeg
{
int x_size, y_size; /* size of image (can be less than block boundary) */
int x_phys, y_phys; /* physical size, block aligned */
int x_mbl; /* x dimension of MBL */
int y_mbl; /* y dimension of MBL */
int blocks; /* blocks per MB */
int restart_interval; /* number of MCUs between RSTm markers */
int store_pos[4]; /* for Y block ordering */
unsigned char* p_entropy_data;
unsigned char* p_entropy_end;
int quanttable[4][QUANT_TABLE_LENGTH]; /* raw quantization tables 0-3 */
int qt_idct[2][QUANT_TABLE_LENGTH]; /* quantization tables for IDCT */
struct huffman_table hufftable[2]; /* Huffman tables */
struct derived_tbl dc_derived_tbls[2]; /* Huffman-LUTs */
struct derived_tbl ac_derived_tbls[2];
struct frame_component frameheader[3]; /* Component descriptor */
struct scan_component scanheader[3]; /* currently not used */
int mcu_membership[6]; /* info per block */
int tab_membership[6];
int subsample_x[3]; /* info per component */
int subsample_y[3];
};
/* possible return flags for process_markers() */
#define HUFFTAB 0x0001 /* with huffman table */
#define QUANTTAB 0x0002 /* with quantization table */
#define APP0_JFIF 0x0004 /* with APP0 segment following JFIF standard */
#define FILL_FF 0x0008 /* with 0xFF padding bytes at begin/end */
#define SOF0 0x0010 /* with SOF0-Segment */
#define DHT 0x0020 /* with Definition of huffman tables */
#define SOS 0x0040 /* with Start-of-Scan segment */
#define DQT 0x0080 /* with definition of quantization table */
/* various helper functions */
void default_huff_tbl(struct jpeg* p_jpeg);
void build_lut(struct jpeg* p_jpeg);
int process_markers(unsigned char* p_src, long size, struct jpeg* p_jpeg);
/* the main decode function */
#ifdef HAVE_LCD_COLOR
int jpeg_decode(struct jpeg* p_jpeg, unsigned char* p_pixel[3],
int downscale, void (*pf_progress)(int current, int total));
#else
int jpeg_decode(struct jpeg* p_jpeg, unsigned char* p_pixel[1], int downscale,
void (*pf_progress)(int current, int total));
#endif
#endif /* _JPEG_JPEG_DECODER_H */
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