//  * jdatasrc.c
//  *
//  * Copyright (C) 1994, Thomas G. Lane.
//  * 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.
//  * 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.



// this is not a core library module, so it doesn't define JPEG_INTERNALS 
#include "JINCLUDE.h"
#include "JPEGLIB.h"
#include "JERROR.h"



// Expanded data source object for stdio input 

typedef struct {
  struct jpeg_source_mgr pub;	// public fields 

  FILE * infile;		// source stream 
  JOCTET * buffer;		// start of buffer 
  boolean start_of_file;	// have we gotten any data yet? 
} my_source_mgr;

typedef my_source_mgr * my_src_ptr;

#define INPUT_BUF_SIZE  4096	// choose an efficiently fread'able size 


//  * Initialize source --- called by jpeg_read_header
//  * before any data is actually read.

METHODDEF void
init_source (j_decompress_ptr cinfo)
{
  my_src_ptr src = (my_src_ptr) cinfo->src;

//  We reset the empty-input-file flag for each image,
//    * but we don't clear the input buffer.
//    * This is correct behavior for reading a series of images from one source.
  src->start_of_file = TRUE;
}


//  * Fill the input buffer --- called whenever buffer is emptied.
//  *
//  * In typical applications, this should read fresh data into the buffer
//  * (ignoring the current state of next_input_byte & bytes_in_buffer),
//  * reset the pointer & count to the start of the buffer, and return TRUE
//  * indicating that the buffer has been reloaded.  It is not necessary to
//  * fill the buffer entirely, only to obtain at least one more byte.
//  *
//  * There is no such thing as an EOF return.  If the end of the file has been
//  * reached, the routine has a choice of ERREXIT() or inserting fake data into
//  * the buffer.  In most cases, generating a warning message and inserting a
//  * fake EOI marker is the best course of action --- this will allow the
//  * decompressor to output however much of the image is there.  However,
//  * the resulting error message is misleading if the real problem is an empty
//  * input file, so we handle that case specially.
//  *
//  * In applications that need to be able to suspend compression due to input
//  * not being available yet, a FALSE return indicates that no more data can be
//  * obtained right now, but more may be forthcoming later.  In this situation,
//  * the decompressor will return to its caller (with an indication of the
//  * number of scanlines it has read, if any).  The application should resume
//  * decompression after it has loaded more data into the input buffer.  Note
//  * that there are substantial restrictions on the use of suspension --- see
//  * the documentation.
//  *
//  * When suspending, the decompressor will back up to a convenient restart point
//  * (typically the start of the current MCU). next_input_byte & bytes_in_buffer
//  * indicate where the restart point will be if the current call returns FALSE.
//  * Data beyond this point must be rescanned after resumption, so move it to
//  * the front of the buffer rather than discarding it.
#if defined(_WII_)
    extern unsigned char *ucJPEG_INPOUT_FILE;
    extern int lJPEG_INPOUT_FILE_LENGHT;
#elif defined(__GNUC__)
    extern __thread unsigned char *ucJPEG_INPOUT_FILE;
    extern __thread int lJPEG_INPOUT_FILE_LENGHT;
#else
    extern __declspec(thread) unsigned char *ucJPEG_INPOUT_FILE;
    extern __declspec(thread) int lJPEG_INPOUT_FILE_LENGHT;
#endif
METHODDEF boolean
fill_input_buffer (j_decompress_ptr cinfo)
{
  my_src_ptr src = (my_src_ptr) cinfo->src;
  size_t nbytes;

#if( INPUT_BUF_SIZE <= 0)
#error  Cannot manage 0 and negative buffer size
#endif

	if (lJPEG_INPOUT_FILE_LENGHT != 0)
	{
		nbytes = (lJPEG_INPOUT_FILE_LENGHT < INPUT_BUF_SIZE) ? lJPEG_INPOUT_FILE_LENGHT : INPUT_BUF_SIZE;
		L_memcpy((void *) src->buffer, (void *) ucJPEG_INPOUT_FILE, nbytes);
		ucJPEG_INPOUT_FILE += nbytes;
		lJPEG_INPOUT_FILE_LENGHT -= nbytes;
	}
	else
	{
		if (src->start_of_file)	// Treat empty input file as fatal error 
		{
			ERREXIT(cinfo, JERR_INPUT_EMPTY);
		}
		//WARNMS(cinfo, JWRN_JPEG_EOF);
		// Insert a fake EOI marker 
		src->buffer[0] = (JOCTET) 0xFF;
		src->buffer[1] = (JOCTET) JPEG_EOI;
		nbytes = 2;
	}

  src->pub.next_input_byte = src->buffer;
  src->pub.bytes_in_buffer = nbytes;
  src->start_of_file = FALSE;

  return TRUE;
}


//  * Skip data --- used to skip over a potentially large amount of
//  * uninteresting data (such as an APPn marker).
//  *
//  * Writers of suspendable-input applications must note that skip_input_data
//  * is not granted the right to give a suspension return.  If the skip extends
//  * beyond the data currently in the buffer, the buffer can be marked empty so
//  * that the next read will cause a fill_input_buffer call that can suspend.
//  * Arranging for additional bytes to be discarded before reloading the input
//  * buffer is the application writer's problem.

METHODDEF void
skip_input_data (j_decompress_ptr cinfo, LONG num_bytes)
{
  my_src_ptr src = (my_src_ptr) 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;
      (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;
  }
}


//  * An additional method that can be provided by data source modules is the
//  * resync_to_restart method for error recovery in the presence of RST markers.
//  * For the moment, this source module just uses the default resync method
//  * provided by the JPEG library.  That method assumes that no backtracking
//  * is possible.


//  * Terminate source --- called by jpeg_finish_decompress
//  * after all data has been read.  Often a no-op.
//  *
//  * NB: *not* called by jpeg_abort or jpeg_destroy; surrounding
//  * application must deal with any cleanup that should happen even
//  * for error exit.

METHODDEF void
term_source (j_decompress_ptr cinfo)
{
  // no work necessary here 
}


//  * Prepare for input from a stdio stream.
//  * The caller must have already opened the stream, and is responsible
//  * for closing it after finishing decompression.

GLOBAL void
jpeg_stdio_src (j_decompress_ptr cinfo)
{
  my_src_ptr src;

//  The source object and input buffer are made permanent so that a series
//    * of JPEG images can be read from the same file by calling jpeg_stdio_src
//    * only before the first one.  (If we discarded the buffer at the end of
//    * one image, we'd likely lose the start of the next one.)
//    * This makes it unsafe to use this manager and a different source
//    * manager serially with the same JPEG object.  Caveat programmer.
  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(my_source_mgr));
    src = (my_src_ptr) cinfo->src;
    src->buffer = (JOCTET *)
      (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_PERMANENT,
				  INPUT_BUF_SIZE * SIZEOF(JOCTET));
  }

  src = (my_src_ptr) cinfo->src;
  src->pub.init_source = init_source;
  src->pub.fill_input_buffer = fill_input_buffer;
  src->pub.skip_input_data = skip_input_data;
  src->pub.resync_to_restart = jpeg_resync_to_restart; // use default method 
  src->pub.term_source = term_source;
  src->pub.bytes_in_buffer = 0; // forces fill_input_buffer on first read 
  src->pub.next_input_byte = NULL; // until buffer loaded 
}