/*+
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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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+
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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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+
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+
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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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+
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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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+
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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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+
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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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+
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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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+
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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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+
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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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+
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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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+
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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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+
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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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+
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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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+
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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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+
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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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+
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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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+
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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_v_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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+
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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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+
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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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+
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+
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/* Additional entry points for buffered-image mode. */+
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+
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#ifdef D_MULTISCAN_FILES_SUPPORTED+
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+
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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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+
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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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+
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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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+
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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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+
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#endif /* D_MULTISCAN_FILES_SUPPORTED */+
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