1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/media/libjpeg/jdatasrc.c Wed Dec 31 06:09:35 2014 +0100
1.3 @@ -0,0 +1,283 @@
1.4 +/*
1.5 + * jdatasrc.c
1.6 + *
1.7 + * This file was part of the Independent JPEG Group's software:
1.8 + * Copyright (C) 1994-1996, Thomas G. Lane.
1.9 + * Modified 2009-2011 by Guido Vollbeding.
1.10 + * libjpeg-turbo Modifications:
1.11 + * Copyright (C) 2013, D. R. Commander.
1.12 + * For conditions of distribution and use, see the accompanying README file.
1.13 + *
1.14 + * This file contains decompression data source routines for the case of
1.15 + * reading JPEG data from memory or from a file (or any stdio stream).
1.16 + * While these routines are sufficient for most applications,
1.17 + * some will want to use a different source manager.
1.18 + * IMPORTANT: we assume that fread() will correctly transcribe an array of
1.19 + * JOCTETs from 8-bit-wide elements on external storage. If char is wider
1.20 + * than 8 bits on your machine, you may need to do some tweaking.
1.21 + */
1.22 +
1.23 +/* this is not a core library module, so it doesn't define JPEG_INTERNALS */
1.24 +#include "jinclude.h"
1.25 +#include "jpeglib.h"
1.26 +#include "jerror.h"
1.27 +
1.28 +
1.29 +/* Expanded data source object for stdio input */
1.30 +
1.31 +typedef struct {
1.32 + struct jpeg_source_mgr pub; /* public fields */
1.33 +
1.34 + FILE * infile; /* source stream */
1.35 + JOCTET * buffer; /* start of buffer */
1.36 + boolean start_of_file; /* have we gotten any data yet? */
1.37 +} my_source_mgr;
1.38 +
1.39 +typedef my_source_mgr * my_src_ptr;
1.40 +
1.41 +#define INPUT_BUF_SIZE 4096 /* choose an efficiently fread'able size */
1.42 +
1.43 +
1.44 +/*
1.45 + * Initialize source --- called by jpeg_read_header
1.46 + * before any data is actually read.
1.47 + */
1.48 +
1.49 +METHODDEF(void)
1.50 +init_source (j_decompress_ptr cinfo)
1.51 +{
1.52 + my_src_ptr src = (my_src_ptr) cinfo->src;
1.53 +
1.54 + /* We reset the empty-input-file flag for each image,
1.55 + * but we don't clear the input buffer.
1.56 + * This is correct behavior for reading a series of images from one source.
1.57 + */
1.58 + src->start_of_file = TRUE;
1.59 +}
1.60 +
1.61 +#if JPEG_LIB_VERSION >= 80 || defined(MEM_SRCDST_SUPPORTED)
1.62 +METHODDEF(void)
1.63 +init_mem_source (j_decompress_ptr cinfo)
1.64 +{
1.65 + /* no work necessary here */
1.66 +}
1.67 +#endif
1.68 +
1.69 +
1.70 +/*
1.71 + * Fill the input buffer --- called whenever buffer is emptied.
1.72 + *
1.73 + * In typical applications, this should read fresh data into the buffer
1.74 + * (ignoring the current state of next_input_byte & bytes_in_buffer),
1.75 + * reset the pointer & count to the start of the buffer, and return TRUE
1.76 + * indicating that the buffer has been reloaded. It is not necessary to
1.77 + * fill the buffer entirely, only to obtain at least one more byte.
1.78 + *
1.79 + * There is no such thing as an EOF return. If the end of the file has been
1.80 + * reached, the routine has a choice of ERREXIT() or inserting fake data into
1.81 + * the buffer. In most cases, generating a warning message and inserting a
1.82 + * fake EOI marker is the best course of action --- this will allow the
1.83 + * decompressor to output however much of the image is there. However,
1.84 + * the resulting error message is misleading if the real problem is an empty
1.85 + * input file, so we handle that case specially.
1.86 + *
1.87 + * In applications that need to be able to suspend compression due to input
1.88 + * not being available yet, a FALSE return indicates that no more data can be
1.89 + * obtained right now, but more may be forthcoming later. In this situation,
1.90 + * the decompressor will return to its caller (with an indication of the
1.91 + * number of scanlines it has read, if any). The application should resume
1.92 + * decompression after it has loaded more data into the input buffer. Note
1.93 + * that there are substantial restrictions on the use of suspension --- see
1.94 + * the documentation.
1.95 + *
1.96 + * When suspending, the decompressor will back up to a convenient restart point
1.97 + * (typically the start of the current MCU). next_input_byte & bytes_in_buffer
1.98 + * indicate where the restart point will be if the current call returns FALSE.
1.99 + * Data beyond this point must be rescanned after resumption, so move it to
1.100 + * the front of the buffer rather than discarding it.
1.101 + */
1.102 +
1.103 +METHODDEF(boolean)
1.104 +fill_input_buffer (j_decompress_ptr cinfo)
1.105 +{
1.106 + my_src_ptr src = (my_src_ptr) cinfo->src;
1.107 + size_t nbytes;
1.108 +
1.109 + nbytes = JFREAD(src->infile, src->buffer, INPUT_BUF_SIZE);
1.110 +
1.111 + if (nbytes <= 0) {
1.112 + if (src->start_of_file) /* Treat empty input file as fatal error */
1.113 + ERREXIT(cinfo, JERR_INPUT_EMPTY);
1.114 + WARNMS(cinfo, JWRN_JPEG_EOF);
1.115 + /* Insert a fake EOI marker */
1.116 + src->buffer[0] = (JOCTET) 0xFF;
1.117 + src->buffer[1] = (JOCTET) JPEG_EOI;
1.118 + nbytes = 2;
1.119 + }
1.120 +
1.121 + src->pub.next_input_byte = src->buffer;
1.122 + src->pub.bytes_in_buffer = nbytes;
1.123 + src->start_of_file = FALSE;
1.124 +
1.125 + return TRUE;
1.126 +}
1.127 +
1.128 +#if JPEG_LIB_VERSION >= 80 || defined(MEM_SRCDST_SUPPORTED)
1.129 +METHODDEF(boolean)
1.130 +fill_mem_input_buffer (j_decompress_ptr cinfo)
1.131 +{
1.132 + static const JOCTET mybuffer[4] = {
1.133 + (JOCTET) 0xFF, (JOCTET) JPEG_EOI, 0, 0
1.134 + };
1.135 +
1.136 + /* The whole JPEG data is expected to reside in the supplied memory
1.137 + * buffer, so any request for more data beyond the given buffer size
1.138 + * is treated as an error.
1.139 + */
1.140 + WARNMS(cinfo, JWRN_JPEG_EOF);
1.141 +
1.142 + /* Insert a fake EOI marker */
1.143 +
1.144 + cinfo->src->next_input_byte = mybuffer;
1.145 + cinfo->src->bytes_in_buffer = 2;
1.146 +
1.147 + return TRUE;
1.148 +}
1.149 +#endif
1.150 +
1.151 +
1.152 +/*
1.153 + * Skip data --- used to skip over a potentially large amount of
1.154 + * uninteresting data (such as an APPn marker).
1.155 + *
1.156 + * Writers of suspendable-input applications must note that skip_input_data
1.157 + * is not granted the right to give a suspension return. If the skip extends
1.158 + * beyond the data currently in the buffer, the buffer can be marked empty so
1.159 + * that the next read will cause a fill_input_buffer call that can suspend.
1.160 + * Arranging for additional bytes to be discarded before reloading the input
1.161 + * buffer is the application writer's problem.
1.162 + */
1.163 +
1.164 +METHODDEF(void)
1.165 +skip_input_data (j_decompress_ptr cinfo, long num_bytes)
1.166 +{
1.167 + struct jpeg_source_mgr * src = cinfo->src;
1.168 +
1.169 + /* Just a dumb implementation for now. Could use fseek() except
1.170 + * it doesn't work on pipes. Not clear that being smart is worth
1.171 + * any trouble anyway --- large skips are infrequent.
1.172 + */
1.173 + if (num_bytes > 0) {
1.174 + while (num_bytes > (long) src->bytes_in_buffer) {
1.175 + num_bytes -= (long) src->bytes_in_buffer;
1.176 + (void) (*src->fill_input_buffer) (cinfo);
1.177 + /* note we assume that fill_input_buffer will never return FALSE,
1.178 + * so suspension need not be handled.
1.179 + */
1.180 + }
1.181 + src->next_input_byte += (size_t) num_bytes;
1.182 + src->bytes_in_buffer -= (size_t) num_bytes;
1.183 + }
1.184 +}
1.185 +
1.186 +
1.187 +/*
1.188 + * An additional method that can be provided by data source modules is the
1.189 + * resync_to_restart method for error recovery in the presence of RST markers.
1.190 + * For the moment, this source module just uses the default resync method
1.191 + * provided by the JPEG library. That method assumes that no backtracking
1.192 + * is possible.
1.193 + */
1.194 +
1.195 +
1.196 +/*
1.197 + * Terminate source --- called by jpeg_finish_decompress
1.198 + * after all data has been read. Often a no-op.
1.199 + *
1.200 + * NB: *not* called by jpeg_abort or jpeg_destroy; surrounding
1.201 + * application must deal with any cleanup that should happen even
1.202 + * for error exit.
1.203 + */
1.204 +
1.205 +METHODDEF(void)
1.206 +term_source (j_decompress_ptr cinfo)
1.207 +{
1.208 + /* no work necessary here */
1.209 +}
1.210 +
1.211 +
1.212 +/*
1.213 + * Prepare for input from a stdio stream.
1.214 + * The caller must have already opened the stream, and is responsible
1.215 + * for closing it after finishing decompression.
1.216 + */
1.217 +
1.218 +GLOBAL(void)
1.219 +jpeg_stdio_src (j_decompress_ptr cinfo, FILE * infile)
1.220 +{
1.221 + my_src_ptr src;
1.222 +
1.223 + /* The source object and input buffer are made permanent so that a series
1.224 + * of JPEG images can be read from the same file by calling jpeg_stdio_src
1.225 + * only before the first one. (If we discarded the buffer at the end of
1.226 + * one image, we'd likely lose the start of the next one.)
1.227 + * This makes it unsafe to use this manager and a different source
1.228 + * manager serially with the same JPEG object. Caveat programmer.
1.229 + */
1.230 + if (cinfo->src == NULL) { /* first time for this JPEG object? */
1.231 + cinfo->src = (struct jpeg_source_mgr *)
1.232 + (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_PERMANENT,
1.233 + SIZEOF(my_source_mgr));
1.234 + src = (my_src_ptr) cinfo->src;
1.235 + src->buffer = (JOCTET *)
1.236 + (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_PERMANENT,
1.237 + INPUT_BUF_SIZE * SIZEOF(JOCTET));
1.238 + }
1.239 +
1.240 + src = (my_src_ptr) cinfo->src;
1.241 + src->pub.init_source = init_source;
1.242 + src->pub.fill_input_buffer = fill_input_buffer;
1.243 + src->pub.skip_input_data = skip_input_data;
1.244 + src->pub.resync_to_restart = jpeg_resync_to_restart; /* use default method */
1.245 + src->pub.term_source = term_source;
1.246 + src->infile = infile;
1.247 + src->pub.bytes_in_buffer = 0; /* forces fill_input_buffer on first read */
1.248 + src->pub.next_input_byte = NULL; /* until buffer loaded */
1.249 +}
1.250 +
1.251 +
1.252 +#if JPEG_LIB_VERSION >= 80 || defined(MEM_SRCDST_SUPPORTED)
1.253 +/*
1.254 + * Prepare for input from a supplied memory buffer.
1.255 + * The buffer must contain the whole JPEG data.
1.256 + */
1.257 +
1.258 +GLOBAL(void)
1.259 +jpeg_mem_src (j_decompress_ptr cinfo,
1.260 + unsigned char * inbuffer, unsigned long insize)
1.261 +{
1.262 + struct jpeg_source_mgr * src;
1.263 +
1.264 + if (inbuffer == NULL || insize == 0) /* Treat empty input as fatal error */
1.265 + ERREXIT(cinfo, JERR_INPUT_EMPTY);
1.266 +
1.267 + /* The source object is made permanent so that a series of JPEG images
1.268 + * can be read from the same buffer by calling jpeg_mem_src only before
1.269 + * the first one.
1.270 + */
1.271 + if (cinfo->src == NULL) { /* first time for this JPEG object? */
1.272 + cinfo->src = (struct jpeg_source_mgr *)
1.273 + (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_PERMANENT,
1.274 + SIZEOF(struct jpeg_source_mgr));
1.275 + }
1.276 +
1.277 + src = cinfo->src;
1.278 + src->init_source = init_mem_source;
1.279 + src->fill_input_buffer = fill_mem_input_buffer;
1.280 + src->skip_input_data = skip_input_data;
1.281 + src->resync_to_restart = jpeg_resync_to_restart; /* use default method */
1.282 + src->term_source = term_source;
1.283 + src->bytes_in_buffer = (size_t) insize;
1.284 + src->next_input_byte = (JOCTET *) inbuffer;
1.285 +}
1.286 +#endif
