/*
 * jpegsrc.c -- Source module for libjpeg
 * (C)Copyright 1998, 99 by Hiroshi Takekawa
 * This file is part of Enfle.
 *
 * Last Modified: Sun Mar  5 06:06:39 2000.
 * $Id: jpegsrc.c,v 1.2 2000/03/22 18:07:01 sian Exp $
 *
 * NOTE: This code needs libjpeg version 6 or later.
 *
 * This software is based in part on the work of the Independent JPEG Group
 *
 * Enfle 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.
 *
 * Enfle is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
 */

#include "archive.h"

#include <stdio.h>
#include <stdlib.h>

#include <jpeglib.h>
#include <jerror.h>
#include <setjmp.h>

#if BITS_IN_JSAMPLE != 8
#  error BITS_IN_JSAMPLE must be 8
#endif

typedef struct {
  struct jpeg_source_mgr pub;  /* public fields */

  Archive *ar;                 /* source archive */
  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 8192

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

  src->start_of_file = TRUE;
}

METHODDEF(boolean)
fill_input_buffer(j_decompress_ptr cinfo)
{
  my_src_ptr src = (my_src_ptr)cinfo->src;
  size_t nbytes;

  nbytes = archive_read(src->ar, src->buffer, INPUT_BUF_SIZE);

  if (nbytes <= 0) {
    if (src->start_of_file)
      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;
}

METHODDEF(void)
skip_input_data(j_decompress_ptr cinfo, long num_bytes)
{
  my_src_ptr src = (my_src_ptr)cinfo->src;

  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);
    }
    src->pub.next_input_byte += (size_t)num_bytes;
    src->pub.bytes_in_buffer -= (size_t)num_bytes;
  }
}

METHODDEF(void)
term_source(j_decompress_ptr cinfo)
{
}

GLOBAL(void)
jpeg_archive_src(j_decompress_ptr cinfo, Archive *ar)
{
  my_src_ptr src;

  if (cinfo->src == NULL) {
    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->ar = ar;
  src->pub.bytes_in_buffer = 0; /* forces fill_input_buffer on first read */
  src->pub.next_input_byte = NULL; /* until buffer loaded */
}