jdk

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/*
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 * reserved comment block
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 * DO NOT REMOVE OR ALTER!
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 */
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/*
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 * jdapistd.c
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 *
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 * Copyright (C) 1994-1996, Thomas G. Lane.
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 * This file is part of the Independent JPEG Group's software.
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 * For conditions of distribution and use, see the accompanying README file.
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 *
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 * This file contains application interface code for the decompression half
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 * of the JPEG library.  These are the "standard" API routines that are
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 * used in the normal full-decompression case.  They are not used by a
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 * transcoding-only application.  Note that if an application links in
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 * jpeg_start_decompress, it will end up linking in the entire decompressor.
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 * We thus must separate this file from jdapimin.c to avoid linking the
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 * whole decompression library into a transcoder.
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 */
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#define JPEG_INTERNALS
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#include "jinclude.h"
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#include "jpeglib.h"
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/* Forward declarations */
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LOCAL(boolean) output_pass_setup JPP((j_decompress_ptr cinfo));
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/*
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 * Decompression initialization.
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 * jpeg_read_header must be completed before calling this.
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 *
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 * If a multipass operating mode was selected, this will do all but the
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 * last pass, and thus may take a great deal of time.
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 *
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 * Returns FALSE if suspended.  The return value need be inspected only if
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 * a suspending data source is used.
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 */
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GLOBAL(boolean)
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jpeg_start_decompress (j_decompress_ptr cinfo)
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{
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  if (cinfo->global_state == DSTATE_READY) {
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    /* First call: initialize master control, select active modules */
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    jinit_master_decompress(cinfo);
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    if (cinfo->buffered_image) {
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      /* No more work here; expecting jpeg_start_output next */
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      cinfo->global_state = DSTATE_BUFIMAGE;
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      return TRUE;
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    }
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    cinfo->global_state = DSTATE_PRELOAD;
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  }
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  if (cinfo->global_state == DSTATE_PRELOAD) {
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    /* If file has multiple scans, absorb them all into the coef buffer */
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    if (cinfo->inputctl->has_multiple_scans) {
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#ifdef D_MULTISCAN_FILES_SUPPORTED
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      for (;;) {
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        int retcode;
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        /* Call progress monitor hook if present */
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        if (cinfo->progress != NULL)
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          (*cinfo->progress->progress_monitor) ((j_common_ptr) cinfo);
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        /* Absorb some more input */
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        retcode = (*cinfo->inputctl->consume_input) (cinfo);
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        if (retcode == JPEG_SUSPENDED)
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          return FALSE;
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        if (retcode == JPEG_REACHED_EOI)
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          break;
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        /* Advance progress counter if appropriate */
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        if (cinfo->progress != NULL &&
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            (retcode == JPEG_ROW_COMPLETED || retcode == JPEG_REACHED_SOS)) {
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          if (++cinfo->progress->pass_counter >= cinfo->progress->pass_limit) {
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            /* jdmaster underestimated number of scans; ratchet up one scan */
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            cinfo->progress->pass_limit += (long) cinfo->total_iMCU_rows;
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          }
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        }
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      }
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#else
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      ERREXIT(cinfo, JERR_NOT_COMPILED);
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#endif /* D_MULTISCAN_FILES_SUPPORTED */
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    }
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    cinfo->output_scan_number = cinfo->input_scan_number;
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  } else if (cinfo->global_state != DSTATE_PRESCAN)
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    ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
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  /* Perform any dummy output passes, and set up for the final pass */
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  return output_pass_setup(cinfo);
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}
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/*
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 * Set up for an output pass, and perform any dummy pass(es) needed.
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 * Common subroutine for jpeg_start_decompress and jpeg_start_output.
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 * Entry: global_state = DSTATE_PRESCAN only if previously suspended.
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 * Exit: If done, returns TRUE and sets global_state for proper output mode.
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 *       If suspended, returns FALSE and sets global_state = DSTATE_PRESCAN.
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 */
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LOCAL(boolean)
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output_pass_setup (j_decompress_ptr cinfo)
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{
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  if (cinfo->global_state != DSTATE_PRESCAN) {
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    /* First call: do pass setup */
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    (*cinfo->master->prepare_for_output_pass) (cinfo);
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    cinfo->output_scanline = 0;
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    cinfo->global_state = DSTATE_PRESCAN;
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  }
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  /* Loop over any required dummy passes */
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  while (cinfo->master->is_dummy_pass) {
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#ifdef QUANT_2PASS_SUPPORTED
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    /* Crank through the dummy pass */
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    while (cinfo->output_scanline < cinfo->output_height) {
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      JDIMENSION last_scanline;
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      /* Call progress monitor hook if present */
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      if (cinfo->progress != NULL) {
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        cinfo->progress->pass_counter = (long) cinfo->output_scanline;
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        cinfo->progress->pass_limit = (long) cinfo->output_height;
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        (*cinfo->progress->progress_monitor) ((j_common_ptr) cinfo);
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      }
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      /* Process some data */
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      last_scanline = cinfo->output_scanline;
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      (*cinfo->main->process_data) (cinfo, (JSAMPARRAY) NULL,
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                                    &cinfo->output_scanline, (JDIMENSION) 0);
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      if (cinfo->output_scanline == last_scanline)
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        return FALSE;           /* No progress made, must suspend */
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    }
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    /* Finish up dummy pass, and set up for another one */
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    (*cinfo->master->finish_output_pass) (cinfo);
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    (*cinfo->master->prepare_for_output_pass) (cinfo);
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    cinfo->output_scanline = 0;
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#else
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    ERREXIT(cinfo, JERR_NOT_COMPILED);
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#endif /* QUANT_2PASS_SUPPORTED */
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  }
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  /* Ready for application to drive output pass through
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   * jpeg_read_scanlines or jpeg_read_raw_data.
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   */
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  cinfo->global_state = cinfo->raw_data_out ? DSTATE_RAW_OK : DSTATE_SCANNING;
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  return TRUE;
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}
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/*
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 * Read some scanlines of data from the JPEG decompressor.
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 *
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 * The return value will be the number of lines actually read.
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 * This may be less than the number requested in several cases,
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 * including bottom of image, data source suspension, and operating
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 * modes that emit multiple scanlines at a time.
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 *
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 * Note: we warn about excess calls to jpeg_read_scanlines() since
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 * this likely signals an application programmer error.  However,
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 * an oversize buffer (max_lines > scanlines remaining) is not an error.
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 */
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GLOBAL(JDIMENSION)
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jpeg_read_scanlines (j_decompress_ptr cinfo, JSAMPARRAY scanlines,
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                     JDIMENSION max_lines)
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{
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  JDIMENSION row_ctr;
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  if (cinfo->global_state != DSTATE_SCANNING)
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    ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
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  if (cinfo->output_scanline >= cinfo->output_height) {
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    WARNMS(cinfo, JWRN_TOO_MUCH_DATA);
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    return 0;
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  }
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  /* Call progress monitor hook if present */
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  if (cinfo->progress != NULL) {
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    cinfo->progress->pass_counter = (long) cinfo->output_scanline;
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    cinfo->progress->pass_limit = (long) cinfo->output_height;
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    (*cinfo->progress->progress_monitor) ((j_common_ptr) cinfo);
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  }
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  /* Process some data */
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  row_ctr = 0;
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  (*cinfo->main->process_data) (cinfo, scanlines, &row_ctr, max_lines);
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  cinfo->output_scanline += row_ctr;
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  return row_ctr;
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}
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/*
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 * Alternate entry point to read raw data.
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 * Processes exactly one iMCU row per call, unless suspended.
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 */
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GLOBAL(JDIMENSION)
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jpeg_read_raw_data (j_decompress_ptr cinfo, JSAMPIMAGE data,
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                    JDIMENSION max_lines)
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{
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  JDIMENSION lines_per_iMCU_row;
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  if (cinfo->global_state != DSTATE_RAW_OK)
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    ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
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  if (cinfo->output_scanline >= cinfo->output_height) {
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    WARNMS(cinfo, JWRN_TOO_MUCH_DATA);
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    return 0;
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  }
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  /* Call progress monitor hook if present */
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  if (cinfo->progress != NULL) {
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    cinfo->progress->pass_counter = (long) cinfo->output_scanline;
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    cinfo->progress->pass_limit = (long) cinfo->output_height;
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    (*cinfo->progress->progress_monitor) ((j_common_ptr) cinfo);
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  }
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  /* Verify that at least one iMCU row can be returned. */
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  lines_per_iMCU_row = cinfo->max_v_samp_factor * cinfo->min_DCT_scaled_size;
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  if (max_lines < lines_per_iMCU_row)
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    ERREXIT(cinfo, JERR_BUFFER_SIZE);
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  /* Decompress directly into user's buffer. */
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  if (! (*cinfo->coef->decompress_data) (cinfo, data))
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    return 0;                   /* suspension forced, can do nothing more */
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  /* OK, we processed one iMCU row. */
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  cinfo->output_scanline += lines_per_iMCU_row;
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  return lines_per_iMCU_row;
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}
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/* Additional entry points for buffered-image mode. */
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#ifdef D_MULTISCAN_FILES_SUPPORTED
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/*
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 * Initialize for an output pass in buffered-image mode.
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 */
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GLOBAL(boolean)
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jpeg_start_output (j_decompress_ptr cinfo, int scan_number)
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{
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  if (cinfo->global_state != DSTATE_BUFIMAGE &&
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      cinfo->global_state != DSTATE_PRESCAN)
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    ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
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  /* Limit scan number to valid range */
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  if (scan_number <= 0)
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    scan_number = 1;
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  if (cinfo->inputctl->eoi_reached &&
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      scan_number > cinfo->input_scan_number)
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    scan_number = cinfo->input_scan_number;
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  cinfo->output_scan_number = scan_number;
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  /* Perform any dummy output passes, and set up for the real pass */
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  return output_pass_setup(cinfo);
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}
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/*
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 * Finish up after an output pass in buffered-image mode.
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 *
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 * Returns FALSE if suspended.  The return value need be inspected only if
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 * a suspending data source is used.
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 */
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GLOBAL(boolean)
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jpeg_finish_output (j_decompress_ptr cinfo)
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{
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  if ((cinfo->global_state == DSTATE_SCANNING ||
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       cinfo->global_state == DSTATE_RAW_OK) && cinfo->buffered_image) {
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    /* Terminate this pass. */
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    /* We do not require the whole pass to have been completed. */
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    (*cinfo->master->finish_output_pass) (cinfo);
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    cinfo->global_state = DSTATE_BUFPOST;
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  } else if (cinfo->global_state != DSTATE_BUFPOST) {
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    /* BUFPOST = repeat call after a suspension, anything else is error */
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    ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
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  }
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  /* Read markers looking for SOS or EOI */
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  while (cinfo->input_scan_number <= cinfo->output_scan_number &&
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         ! cinfo->inputctl->eoi_reached) {
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    if ((*cinfo->inputctl->consume_input) (cinfo) == JPEG_SUSPENDED)
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      return FALSE;             /* Suspend, come back later */
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  }
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  cinfo->global_state = DSTATE_BUFIMAGE;
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  return TRUE;
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}
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#endif /* D_MULTISCAN_FILES_SUPPORTED */
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