    /*
     * jdapimin.c
     *
     * Copyright (C) 1994-1998, 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.
     */

    #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_CreateDecompress (j_decompress_ptr cinfo, int version, size_t structsize)
    {
      int i;

      /* Guard against version mismatches between library and caller. */
      cinfo->mem = NULL;		/* so jpeg_destroy knows mem mgr not called */
      if (version != JPEG_LIB_VERSION)
        ERREXIT2(cinfo, JERR_BAD_LIB_VERSION, JPEG_LIB_VERSION, version);
      if (structsize != SIZEOF(struct jpeg_decompress_struct))
        ERREXIT2(cinfo, JERR_BAD_STRUCT_SIZE,
    	     (int) SIZEOF(struct jpeg_decompress_struct), (int) structsize);

      /* For debugging purposes, we zero the whole master structure.
       * But the application has already set the err pointer, and may have set
       * client_data, so we have to save and restore those fields.
       * Note: if application hasn't set client_data, tools like Purify may
       * complain here.
       */
      {
        struct jpeg_error_mgr * err = cinfo->err;
        void * client_data = cinfo->client_data; /* ignore Purify complaint here */
        MEMZERO(cinfo, SIZEOF(struct jpeg_decompress_struct));
        cinfo->err = err;
        cinfo->client_data = client_data;
      }
      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.
       */
      cinfo->marker_list = NULL;
      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 */
    }

    /*
     * 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, int 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(int)
    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(int)
    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(int)
    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;
    }