//  * jdapimin.c
//  *
//  * Copyright (C) 1994-1995, 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 application interface code for the decompression half
//  * of the JPEG library.  These are the "minimum" API routines that may be
//  * needed in either the normal full-decompression case or the
//  * transcoding-only case.
//  *
//  * Most of the routines intended to be called directly by an application
//  * are in this file or in jdapistd.c.  But also see jcomapi.c for routines
//  * shared by compression and decompression, and jdtrans.c for the transcoding
//  * case.



#ifdef _MSC_VER
    #pragma warning(push)
    #pragma warning(disable: 4127)
#endif


#define JPEG_INTERNALS
#include "JINCLUDE.h"
#include "JPEGLIB.h"


//  * Initialization of a JPEG decompression object.
//  * The error manager must already be set up (in case memory manager fails).

GLOBAL void
jpeg_create_decompress (j_decompress_ptr cinfo)
{
  int i;

//  For debugging purposes, zero the whole master structure.
//    * But error manager pointer is already there, so save and restore it.
  {
    struct jpeg_error_mgr * err = cinfo->err;
    MEMZERO(cinfo, SIZEOF(struct jpeg_decompress_struct));
    cinfo->err = err;
  }
  cinfo->is_decompressor = TRUE;

  // Initialize a memory manager instance for this object 
  jinit_memory_mgr((j_common_ptr) cinfo);

  // Zero out pointers to permanent structures. 
  cinfo->progress = NULL;
  cinfo->src = NULL;

  for (i = 0; i < NUM_QUANT_TBLS; i++)
    cinfo->quant_tbl_ptrs[i] = NULL;

  for (i = 0; i < NUM_HUFF_TBLS; i++) {
    cinfo->dc_huff_tbl_ptrs[i] = NULL;
    cinfo->ac_huff_tbl_ptrs[i] = NULL;
  }

//  Initialize marker processor so application can override methods
//    * for COM, APPn markers before calling jpeg_read_header.
  jinit_marker_reader(cinfo);

  // And initialize the overall input controller. 
  jinit_input_controller(cinfo);

  // OK, I'm ready 
  cinfo->global_state = DSTATE_START;
}


//  * Destruction of a JPEG decompression object

GLOBAL void
jpeg_destroy_decompress (j_decompress_ptr cinfo)
{
  jpeg_destroy((j_common_ptr) cinfo); // use common routine 
}


//  * Abort processing of a JPEG decompression operation,
//  * but don't destroy the object itself.

GLOBAL void
jpeg_abort_decompress (j_decompress_ptr cinfo)
{
  jpeg_abort((j_common_ptr) cinfo); // use common routine 
}


//  * Install a special processing method for COM or APPn markers.

GLOBAL void
jpeg_set_marker_processor (j_decompress_ptr cinfo, int marker_code,
			   jpeg_marker_parser_method routine)
{
  if (marker_code == JPEG_COM)
    cinfo->marker->process_COM = routine;
  else if (marker_code >= JPEG_APP0 && marker_code <= JPEG_APP0+15)
    cinfo->marker->process_APPn[marker_code-JPEG_APP0] = routine;
  else
    ERREXIT1(cinfo, JERR_UNKNOWN_MARKER, marker_code);
}


//  * Set default decompression parameters.

LOCAL void
default_decompress_parms (j_decompress_ptr cinfo)
{
  // Guess the input colorspace, and set output colorspace accordingly. 
  // (Wish JPEG committee had provided a real way to specify this...) 
  // Note application may override our guesses. 
  switch (cinfo->num_components) {
  case 1:
    cinfo->jpeg_color_space = JCS_GRAYSCALE;
    cinfo->out_color_space = JCS_GRAYSCALE;
    break;

  case 3:
    if (cinfo->saw_JFIF_marker) {
      cinfo->jpeg_color_space = JCS_YCbCr; // JFIF implies YCbCr 
    } else if (cinfo->saw_Adobe_marker) {
      switch (cinfo->Adobe_transform) {
      case 0:
	cinfo->jpeg_color_space = JCS_RGB;
	break;
      case 1:
	cinfo->jpeg_color_space = JCS_YCbCr;
	break;
      default:
	WARNMS1(cinfo, JWRN_ADOBE_XFORM, cinfo->Adobe_transform);
	cinfo->jpeg_color_space = JCS_YCbCr; // assume it's YCbCr 
	break;
      }
    } else {
      // Saw no special markers, try to guess from the component IDs 
      int cid0 = cinfo->comp_info[0].component_id;
      int cid1 = cinfo->comp_info[1].component_id;
      int cid2 = cinfo->comp_info[2].component_id;

      if (cid0 == 1 && cid1 == 2 && cid2 == 3)
	cinfo->jpeg_color_space = JCS_YCbCr; // assume JFIF w/out marker 
      else if (cid0 == 82 && cid1 == 71 && cid2 == 66)
	cinfo->jpeg_color_space = JCS_RGB; // ASCII 'R', 'G', 'B' 
      else {
	TRACEMS3(cinfo, 1, JTRC_UNKNOWN_IDS, cid0, cid1, cid2);
	cinfo->jpeg_color_space = JCS_YCbCr; // assume it's YCbCr 
      }
    }
    // Always guess RGB is proper output colorspace. 
    cinfo->out_color_space = JCS_RGB;
    break;

  case 4:
    if (cinfo->saw_Adobe_marker) {
      switch (cinfo->Adobe_transform) {
      case 0:
	cinfo->jpeg_color_space = JCS_CMYK;
	break;
      case 2:
	cinfo->jpeg_color_space = JCS_YCCK;
	break;
      default:
	WARNMS1(cinfo, JWRN_ADOBE_XFORM, cinfo->Adobe_transform);
	cinfo->jpeg_color_space = JCS_YCCK; // assume it's YCCK 
	break;
      }
    } else {
      // No special markers, assume straight CMYK. 
      cinfo->jpeg_color_space = JCS_CMYK;
    }
    cinfo->out_color_space = JCS_CMYK;
    break;

  default:
    cinfo->jpeg_color_space = JCS_UNKNOWN;
    cinfo->out_color_space = JCS_UNKNOWN;
    break;
  }

  // Set defaults for other decompression parameters. 
  cinfo->scale_num = 1;		// 1:1 scaling 
  cinfo->scale_denom = 1;
  cinfo->output_gamma = 1.0;
  cinfo->buffered_image = FALSE;
  cinfo->raw_data_out = FALSE;
  cinfo->dct_method = JDCT_DEFAULT;
  cinfo->do_fancy_upsampling = TRUE;
  cinfo->do_block_smoothing = TRUE;
  cinfo->quantize_colors = FALSE;
  // We set these in case application only sets quantize_colors. 
  cinfo->dither_mode = JDITHER_FS;
#ifdef QUANT_2PASS_SUPPORTED
  cinfo->two_pass_quantize = TRUE;
#else
  cinfo->two_pass_quantize = FALSE;
#endif
  cinfo->desired_number_of_colors = 256;
  cinfo->colormap = NULL;
  // Initialize for no mode change in buffered-image mode. 
  cinfo->enable_1pass_quant = FALSE;
  cinfo->enable_external_quant = FALSE;
  cinfo->enable_2pass_quant = FALSE;
}


//  * Decompression startup: read start of JPEG datastream to see what's there.
//  * Need only initialize JPEG object and supply a data source before calling.
//  *
//  * This routine will read as far as the first SOS marker (ie, actual start of
//  * compressed data), and will save all tables and parameters in the JPEG
//  * object.  It will also initialize the decompression parameters to default
//  * values, and finally return JPEG_HEADER_OK.  On return, the application may
//  * adjust the decompression parameters and then call jpeg_start_decompress.
//  * (Or, if the application only wanted to determine the image parameters,
//  * the data need not be decompressed.  In that case, call jpeg_abort or
//  * jpeg_destroy to release any temporary space.)
//  * If an abbreviated (tables only) datastream is presented, the routine will
//  * return JPEG_HEADER_TABLES_ONLY upon reaching EOI.  The application may then
//  * re-use the JPEG object to read the abbreviated image datastream(s).
//  * It is unnecessary (but OK) to call jpeg_abort in this case.
//  * The JPEG_SUSPENDED return code only occurs if the data source module
//  * requests suspension of the decompressor.  In this case the application
//  * should load more source data and then re-call jpeg_read_header to resume
//  * processing.
//  * If a non-suspending data source is used and require_image is TRUE, then the
//  * return code need not be inspected since only JPEG_HEADER_OK is possible.
//  *
//  * This routine is now just a front end to jpeg_consume_input, with some
//  * extra error checking.

GLOBAL int
jpeg_read_header (j_decompress_ptr cinfo, boolean require_image)
{
  int retcode;

  if (cinfo->global_state != DSTATE_START &&
      cinfo->global_state != DSTATE_INHEADER)
    ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);

  retcode = jpeg_consume_input(cinfo);

  switch (retcode) {
  case JPEG_REACHED_SOS:
    retcode = JPEG_HEADER_OK;
    break;
  case JPEG_REACHED_EOI:
    if (require_image)		// Complain if application wanted an image 
      ERREXIT(cinfo, JERR_NO_IMAGE);
//  Reset to start state; it would be safer to require the application to
//      * call jpeg_abort, but we can't change it now for compatibility reasons.
//      * A side effect is to free any temporary memory (there shouldn't be any).
    jpeg_abort((j_common_ptr) cinfo); // sets state = DSTATE_START 
    retcode = JPEG_HEADER_TABLES_ONLY;
    break;
  case JPEG_SUSPENDED:
    // no work 
    break;
  }

  return retcode;
}


//  * Consume data in advance of what the decompressor requires.
//  * This can be called at any time once the decompressor object has
//  * been created and a data source has been set up.
//  *
//  * This routine is essentially a state machine that handles a couple
//  * of critical state-transition actions, namely initial setup and
//  * transition from header scanning to ready-for-start_decompress.
//  * All the actual input is done via the input controller's consume_input
//  * method.

GLOBAL int
jpeg_consume_input (j_decompress_ptr cinfo)
{
  int retcode = JPEG_SUSPENDED;

  // NB: every possible DSTATE value should be listed in this switch 
  switch (cinfo->global_state) {
  case DSTATE_START:
    // Start-of-datastream actions: reset appropriate modules 
    (*cinfo->inputctl->reset_input_controller) (cinfo);
    // Initialize application's data source module 
    (*cinfo->src->init_source) (cinfo);
    cinfo->global_state = DSTATE_INHEADER;
    //FALLTHROUGH
  case DSTATE_INHEADER:
    retcode = (*cinfo->inputctl->consume_input) (cinfo);
    if (retcode == JPEG_REACHED_SOS) { // Found SOS, prepare to decompress 
      // Set up default parameters based on header data 
      default_decompress_parms(cinfo);
      // Set global state: ready for start_decompress 
      cinfo->global_state = DSTATE_READY;
    }
    break;
  case DSTATE_READY:
    // Can't advance past first SOS until start_decompress is called 
    retcode = JPEG_REACHED_SOS;
    break;
  case DSTATE_PRELOAD:
  case DSTATE_PRESCAN:
  case DSTATE_SCANNING:
  case DSTATE_RAW_OK:
  case DSTATE_BUFIMAGE:
  case DSTATE_BUFPOST:
  case DSTATE_STOPPING:
    retcode = (*cinfo->inputctl->consume_input) (cinfo);
    break;
  default:
    ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
  }
  return retcode;
}


//  * Have we finished reading the input file?

GLOBAL boolean
jpeg_input_complete (j_decompress_ptr cinfo)
{
  // Check for valid jpeg object 
  if (cinfo->global_state < DSTATE_START ||
      cinfo->global_state > DSTATE_STOPPING)
    ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
  return cinfo->inputctl->eoi_reached;
}


//  * Is there more than one scan?

GLOBAL boolean
jpeg_has_multiple_scans (j_decompress_ptr cinfo)
{
  // Only valid after jpeg_read_header completes 
  if (cinfo->global_state < DSTATE_READY ||
      cinfo->global_state > DSTATE_STOPPING)
    ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
  return cinfo->inputctl->has_multiple_scans;
}


//  * Finish JPEG decompression.
//  *
//  * This will normally just verify the file trailer and release temp storage.
//  *
//  * Returns FALSE if suspended.  The return value need be inspected only if
//  * a suspending data source is used.

GLOBAL boolean
jpeg_finish_decompress (j_decompress_ptr cinfo)
{
  if ((cinfo->global_state == DSTATE_SCANNING ||
       cinfo->global_state == DSTATE_RAW_OK) && ! cinfo->buffered_image) {
    // Terminate final pass of non-buffered mode 
    if (cinfo->output_scanline < cinfo->output_height)
      ERREXIT(cinfo, JERR_TOO_LITTLE_DATA);
    (*cinfo->master->finish_output_pass) (cinfo);
    cinfo->global_state = DSTATE_STOPPING;
  } else if (cinfo->global_state == DSTATE_BUFIMAGE) {
    // Finishing after a buffered-image operation 
    cinfo->global_state = DSTATE_STOPPING;
  } else if (cinfo->global_state != DSTATE_STOPPING) {
    // STOPPING = repeat call after a suspension, anything else is error 
    ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
  }
  // Read until EOI 
  while (! cinfo->inputctl->eoi_reached) {
    if ((*cinfo->inputctl->consume_input) (cinfo) == JPEG_SUSPENDED)
      return FALSE;		// Suspend, come back later 
  }
  // Do final cleanup 
  (*cinfo->src->term_source) (cinfo);
  // We can use jpeg_abort to release memory and reset global_state 
  jpeg_abort((j_common_ptr) cinfo);
  return TRUE;
}

#ifdef _MSC_VER
    #pragma warning(pop)
#endif