From 76596deaf1c90f107d43542bf60c9bad1a7ffd68 Mon Sep 17 00:00:00 2001
From: Dave Chapman <dave@dchapman.com>
Date: Tue, 21 Oct 2008 16:05:46 +0000
Subject: Move the monolithic jpeg viewer into its own subdirectory and split
 it into three (for now - maybe it should be split further) files - jpeg.c
 (the main plugin/viewer parts), jpeg_decoder.c (the actual decoder) and. for
 colour targets only, yuv2rgb.c.  The intention of this commit is as a first
 step towards abstracting this viewer into a reusable jpeg decoder and a
 multi-format image viewer.

git-svn-id: svn://svn.rockbox.org/rockbox/trunk@18853 a1c6a512-1295-4272-9138-f99709370657
---
 apps/plugins/jpeg/jpeg_decoder.h | 142 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 142 insertions(+)
 create mode 100644 apps/plugins/jpeg/jpeg_decoder.h

(limited to 'apps/plugins/jpeg/jpeg_decoder.h')

diff --git a/apps/plugins/jpeg/jpeg_decoder.h b/apps/plugins/jpeg/jpeg_decoder.h
new file mode 100644
index 0000000..f4dbeaa
--- /dev/null
+++ b/apps/plugins/jpeg/jpeg_decoder.h
@@ -0,0 +1,142 @@
+/***************************************************************************
+*             __________               __   ___.
+*   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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