The Independent JPEG Group's JPEG software v8
diff --git a/jdatasrc.c b/jdatasrc.c
index edc752b..d3136db 100644
--- a/jdatasrc.c
+++ b/jdatasrc.c
@@ -2,13 +2,14 @@
* jdatasrc.c
*
* Copyright (C) 1994-1996, Thomas G. Lane.
+ * Modified 2009 by Guido Vollbeding.
* This file is part of the Independent JPEG Group's software.
* For conditions of distribution and use, see the accompanying README file.
*
* This file contains decompression data source routines for the case of
- * reading JPEG data from a file (or any stdio stream). While these routines
- * are sufficient for most applications, some will want to use a different
- * source manager.
+ * reading JPEG data from memory or from a file (or any stdio stream).
+ * While these routines are sufficient for most applications,
+ * some will want to use a different source manager.
* IMPORTANT: we assume that fread() will correctly transcribe an array of
* JOCTETs from 8-bit-wide elements on external storage. If char is wider
* than 8 bits on your machine, you may need to do some tweaking.
@@ -52,6 +53,12 @@
src->start_of_file = TRUE;
}
+METHODDEF(void)
+init_mem_source (j_decompress_ptr cinfo)
+{
+ /* no work necessary here */
+}
+
/*
* Fill the input buffer --- called whenever buffer is emptied.
@@ -111,6 +118,26 @@
return TRUE;
}
+METHODDEF(boolean)
+fill_mem_input_buffer (j_decompress_ptr cinfo)
+{
+ static JOCTET mybuffer[4];
+
+ /* The whole JPEG data is expected to reside in the supplied memory
+ * buffer, so any request for more data beyond the given buffer size
+ * is treated as an error.
+ */
+ WARNMS(cinfo, JWRN_JPEG_EOF);
+ /* Insert a fake EOI marker */
+ mybuffer[0] = (JOCTET) 0xFF;
+ mybuffer[1] = (JOCTET) JPEG_EOI;
+
+ cinfo->src->next_input_byte = mybuffer;
+ cinfo->src->bytes_in_buffer = 2;
+
+ return TRUE;
+}
+
/*
* Skip data --- used to skip over a potentially large amount of
@@ -127,22 +154,22 @@
METHODDEF(void)
skip_input_data (j_decompress_ptr cinfo, long num_bytes)
{
- my_src_ptr src = (my_src_ptr) cinfo->src;
+ struct jpeg_source_mgr * src = cinfo->src;
/* Just a dumb implementation for now. Could use fseek() except
* it doesn't work on pipes. Not clear that being smart is worth
* any trouble anyway --- large skips are infrequent.
*/
if (num_bytes > 0) {
- while (num_bytes > (long) src->pub.bytes_in_buffer) {
- num_bytes -= (long) src->pub.bytes_in_buffer;
+ while (num_bytes > (long) src->bytes_in_buffer) {
+ num_bytes -= (long) src->bytes_in_buffer;
(void) fill_input_buffer(cinfo);
/* note we assume that fill_input_buffer will never return FALSE,
* so suspension need not be handled.
*/
}
- src->pub.next_input_byte += (size_t) num_bytes;
- src->pub.bytes_in_buffer -= (size_t) num_bytes;
+ src->next_input_byte += (size_t) num_bytes;
+ src->bytes_in_buffer -= (size_t) num_bytes;
}
}
@@ -210,3 +237,38 @@
src->pub.bytes_in_buffer = 0; /* forces fill_input_buffer on first read */
src->pub.next_input_byte = NULL; /* until buffer loaded */
}
+
+
+/*
+ * Prepare for input from a supplied memory buffer.
+ * The buffer must contain the whole JPEG data.
+ */
+
+GLOBAL(void)
+jpeg_mem_src (j_decompress_ptr cinfo,
+ unsigned char * inbuffer, unsigned long insize)
+{
+ struct jpeg_source_mgr * src;
+
+ if (inbuffer == NULL || insize == 0) /* Treat empty input as fatal error */
+ ERREXIT(cinfo, JERR_INPUT_EMPTY);
+
+ /* The source object is made permanent so that a series of JPEG images
+ * can be read from the same buffer by calling jpeg_mem_src only before
+ * the first one.
+ */
+ if (cinfo->src == NULL) { /* first time for this JPEG object? */
+ cinfo->src = (struct jpeg_source_mgr *)
+ (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_PERMANENT,
+ SIZEOF(struct jpeg_source_mgr));
+ }
+
+ src = cinfo->src;
+ src->init_source = init_mem_source;
+ src->fill_input_buffer = fill_mem_input_buffer;
+ src->skip_input_data = skip_input_data;
+ src->resync_to_restart = jpeg_resync_to_restart; /* use default method */
+ src->term_source = term_source;
+ src->bytes_in_buffer = (size_t) insize;
+ src->next_input_byte = (JOCTET *) inbuffer;
+}