    /*
     * jdcoefct.c
     *
     * Copyright (C) 1994-1997, Thomas G. Lane.
     * Modified 2002-2020 by Guido Vollbeding.
     * 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 the coefficient buffer controller for decompression.
     * This controller is the top level of the JPEG decompressor proper.
     * The coefficient buffer lies between entropy decoding and inverse-DCT steps.
     *
     * In buffered-image mode, this controller is the interface between
     * input-oriented processing and output-oriented processing.
     * Also, the input side (only) is used when reading a file for transcoding.
     */

    #define JPEG_INTERNALS
    #include "jinclude.h"
    #include "jpeglib.h"

    /* Block smoothing is only applicable for progressive JPEG, so: */
    #ifndef D_PROGRESSIVE_SUPPORTED
    #undef BLOCK_SMOOTHING_SUPPORTED
    #endif

    /* Private buffer controller object */

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

      /* These variables keep track of the current location of the input side. */
      /* cinfo->input_iMCU_row is also used for this. */
      JDIMENSION MCU_ctr;		/* counts MCUs processed in current row */
      int MCU_vert_offset;		/* counts MCU rows within iMCU row */
      int MCU_rows_per_iMCU_row;	/* number of such rows needed */

      /* The output side's location is represented by cinfo->output_iMCU_row. */

      /* In single-pass modes, it's sufficient to buffer just one MCU.
       * We append a workspace of D_MAX_BLOCKS_IN_MCU coefficient blocks,
       * and let the entropy decoder write into that workspace each time.
       * In multi-pass modes, this array points to the current MCU's blocks
       * within the virtual arrays; it is used only by the input side.
       */
      JBLOCKROW MCU_buffer[D_MAX_BLOCKS_IN_MCU];

    #ifdef D_MULTISCAN_FILES_SUPPORTED
      /* In multi-pass modes, we need a virtual block array for each component. */
      jvirt_barray_ptr whole_image[MAX_COMPONENTS];
    #endif

    #ifdef BLOCK_SMOOTHING_SUPPORTED
      /* When doing block smoothing, we latch coefficient Al values here */
      int * coef_bits_latch;
    #define SAVED_COEFS  6		/* we save coef_bits[0..5] */
    #endif

      /* Workspace for single-pass modes (omitted otherwise). */
      JBLOCK blk_buffer[D_MAX_BLOCKS_IN_MCU];
    } my_coef_controller;

    typedef my_coef_controller * my_coef_ptr;

    /* Forward declarations */
    METHODDEF(int) decompress_onepass
    	JPP((j_decompress_ptr cinfo, JSAMPIMAGE output_buf));
    #ifdef D_MULTISCAN_FILES_SUPPORTED
    METHODDEF(int) decompress_data
    	JPP((j_decompress_ptr cinfo, JSAMPIMAGE output_buf));
    #endif
    #ifdef BLOCK_SMOOTHING_SUPPORTED
    LOCAL(boolean) smoothing_ok JPP((j_decompress_ptr cinfo));
    METHODDEF(int) decompress_smooth_data
    	JPP((j_decompress_ptr cinfo, JSAMPIMAGE output_buf));
    #endif

    LOCAL(void)
    start_iMCU_row (j_decompress_ptr cinfo)
    /* Reset within-iMCU-row counters for a new row (input side) */
    {
      my_coef_ptr coef = (my_coef_ptr) cinfo->coef;

      /* In an interleaved scan, an MCU row is the same as an iMCU row.
       * In a noninterleaved scan, an iMCU row has v_samp_factor MCU rows.
       * But at the bottom of the image, process only what's left.
       */
      if (cinfo->comps_in_scan > 1) {
        coef->MCU_rows_per_iMCU_row = 1;
      } else {
        if (cinfo->input_iMCU_row < (cinfo->total_iMCU_rows-1))
          coef->MCU_rows_per_iMCU_row = cinfo->cur_comp_info[0]->v_samp_factor;
        else
          coef->MCU_rows_per_iMCU_row = cinfo->cur_comp_info[0]->last_row_height;
      }

      coef->MCU_ctr = 0;
      coef->MCU_vert_offset = 0;
    }

    /*
     * Initialize for an input processing pass.
     */

    METHODDEF(void)
    start_input_pass (j_decompress_ptr cinfo)
    {
      cinfo->input_iMCU_row = 0;
      start_iMCU_row(cinfo);
    }

    /*
     * Initialize for an output processing pass.
     */

    METHODDEF(void)
    start_output_pass (j_decompress_ptr cinfo)
    {
    #ifdef BLOCK_SMOOTHING_SUPPORTED
      my_coef_ptr coef = (my_coef_ptr) cinfo->coef;

      /* If multipass, check to see whether to use block smoothing on this pass */
      if (coef->pub.coef_arrays != NULL) {
        if (cinfo->do_block_smoothing && smoothing_ok(cinfo))
          coef->pub.decompress_data = decompress_smooth_data;
        else
          coef->pub.decompress_data = decompress_data;
      }
    #endif
      cinfo->output_iMCU_row = 0;
    }

    /*
     * Decompress and return some data in the single-pass case.
     * Always attempts to emit one fully interleaved MCU row ("iMCU" row).
     * Input and output must run in lockstep since we have only a one-MCU buffer.
     * Return value is JPEG_ROW_COMPLETED, JPEG_SCAN_COMPLETED, or JPEG_SUSPENDED.
     *
     * NB: output_buf contains a plane for each component in image,
     * which we index according to the component's SOF position.
     */

    METHODDEF(int)
    decompress_onepass (j_decompress_ptr cinfo, JSAMPIMAGE output_buf)
    {
      my_coef_ptr coef = (my_coef_ptr) cinfo->coef;
      JDIMENSION MCU_col_num;	/* index of current MCU within row */
      JDIMENSION last_MCU_col = cinfo->MCUs_per_row - 1;
      JDIMENSION last_iMCU_row = cinfo->total_iMCU_rows - 1;
      int ci, xindex, yindex, yoffset, useful_width;
      JBLOCKROW blkp;
      JSAMPARRAY output_ptr;
      JDIMENSION start_col, output_col;
      jpeg_component_info *compptr;
      inverse_DCT_method_ptr inverse_DCT;

      /* Loop to process as much as one whole iMCU row */
      for (yoffset = coef->MCU_vert_offset; yoffset < coef->MCU_rows_per_iMCU_row;
           yoffset++) {
        for (MCU_col_num = coef->MCU_ctr; MCU_col_num <= last_MCU_col;
    	 MCU_col_num++) {
          blkp = coef->blk_buffer;	/* pointer to current DCT block within MCU */
          /* Try to fetch an MCU.  Entropy decoder expects buffer to be zeroed. */
          if (cinfo->lim_Se)	/* can bypass in DC only case */
    	MEMZERO(blkp, cinfo->blocks_in_MCU * SIZEOF(JBLOCK));
          if (! (*cinfo->entropy->decode_mcu) (cinfo, coef->MCU_buffer)) {
    	/* Suspension forced; update state counters and exit */
    	coef->MCU_vert_offset = yoffset;
    	coef->MCU_ctr = MCU_col_num;
    	return JPEG_SUSPENDED;
          }
          /* Determine where data should go in output_buf and do the IDCT thing.
           * We skip dummy blocks at the right and bottom edges (but blkp gets
           * incremented past them!).
           */
          for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
    	compptr = cinfo->cur_comp_info[ci];
    	/* Don't bother to IDCT an uninteresting component. */
    	if (! compptr->component_needed) {
    	  blkp += compptr->MCU_blocks;
    	  continue;
    	}
    	inverse_DCT = cinfo->idct->inverse_DCT[compptr->component_index];
    	output_ptr = output_buf[compptr->component_index] +
    	  yoffset * compptr->DCT_v_scaled_size;
    	useful_width = (MCU_col_num < last_MCU_col) ? compptr->MCU_width
    						    : compptr->last_col_width;
    	start_col = MCU_col_num * compptr->MCU_sample_width;
    	for (yindex = 0; yindex < compptr->MCU_height; yindex++) {
    	  if (cinfo->input_iMCU_row < last_iMCU_row ||
    	      yoffset + yindex < compptr->last_row_height) {
    	    output_col = start_col;
    	    for (xindex = 0; xindex < useful_width; xindex++) {
    	      (*inverse_DCT) (cinfo, compptr, (JCOEFPTR) (blkp + xindex),
    			      output_ptr, output_col);
    	      output_col += compptr->DCT_h_scaled_size;
    	    }
    	    output_ptr += compptr->DCT_v_scaled_size;
    	  }
    	  blkp += compptr->MCU_width;
    	}
          }
        }
        /* Completed an MCU row, but perhaps not an iMCU row */
        coef->MCU_ctr = 0;
      }
      /* Completed the iMCU row, advance counters for next one */
      cinfo->output_iMCU_row++;
      if (++(cinfo->input_iMCU_row) <= last_iMCU_row) {
        start_iMCU_row(cinfo);
        return JPEG_ROW_COMPLETED;
      }
      /* Completed the scan */
      (*cinfo->inputctl->finish_input_pass) (cinfo);
      return JPEG_SCAN_COMPLETED;
    }

    /*
     * Dummy consume-input routine for single-pass operation.
     */

    METHODDEF(int)
    dummy_consume_data (j_decompress_ptr cinfo)
    {
      return JPEG_SUSPENDED;	/* Always indicate nothing was done */
    }

    #ifdef D_MULTISCAN_FILES_SUPPORTED

    /*
     * Consume input data and store it in the full-image coefficient buffer.
     * We read as much as one fully interleaved MCU row ("iMCU" row) per call,
     * ie, v_samp_factor block rows for each component in the scan.
     * Return value is JPEG_ROW_COMPLETED, JPEG_SCAN_COMPLETED, or JPEG_SUSPENDED.
     */

    METHODDEF(int)
    consume_data (j_decompress_ptr cinfo)
    {
      my_coef_ptr coef = (my_coef_ptr) cinfo->coef;
      JDIMENSION MCU_col_num;	/* index of current MCU within row */
      int ci, xindex, yindex, yoffset;
      JDIMENSION start_col;
      JBLOCKARRAY blkp;
      JBLOCKARRAY buffer[MAX_COMPS_IN_SCAN];
      JBLOCKROW buffer_ptr;
      jpeg_component_info *compptr;

      /* Align the virtual buffers for the components used in this scan. */
      for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
        compptr = cinfo->cur_comp_info[ci];
        buffer[ci] = (*cinfo->mem->access_virt_barray)
          ((j_common_ptr) cinfo, coef->whole_image[compptr->component_index],
           cinfo->input_iMCU_row * compptr->v_samp_factor,
           (JDIMENSION) compptr->v_samp_factor, TRUE);
        /* Note: entropy decoder expects buffer to be zeroed,
         * but this is handled automatically by the memory manager
         * because we requested a pre-zeroed array.
         */
      }

      /* Loop to process one whole iMCU row */
      for (yoffset = coef->MCU_vert_offset; yoffset < coef->MCU_rows_per_iMCU_row;
           yoffset++) {
        for (MCU_col_num = coef->MCU_ctr; MCU_col_num < cinfo->MCUs_per_row;
    	 MCU_col_num++) {
          /* Construct list of pointers to DCT blocks belonging to this MCU */
          blkp = coef->MCU_buffer;	/* pointer to current DCT block within MCU */
          for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
    	compptr = cinfo->cur_comp_info[ci];
    	start_col = MCU_col_num * compptr->MCU_width;
    	for (yindex = 0; yindex < compptr->MCU_height; yindex++) {
    	  buffer_ptr = buffer[ci][yoffset + yindex] + start_col;
    	  xindex = compptr->MCU_width;
    	  do {
    	    *blkp++ = buffer_ptr++;
    	  } while (--xindex);
    	}
          }
          /* Try to fetch the MCU. */
          if (! (*cinfo->entropy->decode_mcu) (cinfo, coef->MCU_buffer)) {
    	/* Suspension forced; update state counters and exit */
    	coef->MCU_vert_offset = yoffset;
    	coef->MCU_ctr = MCU_col_num;
    	return JPEG_SUSPENDED;
          }
        }
        /* Completed an MCU row, but perhaps not an iMCU row */
        coef->MCU_ctr = 0;
      }
      /* Completed the iMCU row, advance counters for next one */
      if (++(cinfo->input_iMCU_row) < cinfo->total_iMCU_rows) {
        start_iMCU_row(cinfo);
        return JPEG_ROW_COMPLETED;
      }
      /* Completed the scan */
      (*cinfo->inputctl->finish_input_pass) (cinfo);
      return JPEG_SCAN_COMPLETED;
    }

    /*
     * Decompress and return some data in the multi-pass case.
     * Always attempts to emit one fully interleaved MCU row ("iMCU" row).
     * Return value is JPEG_ROW_COMPLETED, JPEG_SCAN_COMPLETED, or JPEG_SUSPENDED.
     *
     * NB: output_buf contains a plane for each component in image.
     */

    METHODDEF(int)
    decompress_data (j_decompress_ptr cinfo, JSAMPIMAGE output_buf)
    {
      my_coef_ptr coef = (my_coef_ptr) cinfo->coef;
      JDIMENSION last_iMCU_row = cinfo->total_iMCU_rows - 1;
      JDIMENSION block_num;
      int ci, block_row, block_rows;
      JBLOCKARRAY buffer;
      JBLOCKROW buffer_ptr;
      JSAMPARRAY output_ptr;
      JDIMENSION output_col;
      jpeg_component_info *compptr;
      inverse_DCT_method_ptr inverse_DCT;

      /* Force some input to be done if we are getting ahead of the input. */
      while (cinfo->input_scan_number < cinfo->output_scan_number ||
    	 (cinfo->input_scan_number == cinfo->output_scan_number &&
    	  cinfo->input_iMCU_row <= cinfo->output_iMCU_row)) {
        if ((*cinfo->inputctl->consume_input)(cinfo) == JPEG_SUSPENDED)
          return JPEG_SUSPENDED;
      }

      /* OK, output from the virtual arrays. */
      for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
           ci++, compptr++) {
        /* Don't bother to IDCT an uninteresting component. */
        if (! compptr->component_needed)
          continue;
        /* Align the virtual buffer for this component. */
        buffer = (*cinfo->mem->access_virt_barray)
          ((j_common_ptr) cinfo, coef->whole_image[ci],
           cinfo->output_iMCU_row * compptr->v_samp_factor,
           (JDIMENSION) compptr->v_samp_factor, FALSE);
        /* Count non-dummy DCT block rows in this iMCU row. */
        if (cinfo->output_iMCU_row < last_iMCU_row)
          block_rows = compptr->v_samp_factor;
        else {
          /* NB: can't use last_row_height here; it is input-side-dependent! */
          block_rows = (int) (compptr->height_in_blocks % compptr->v_samp_factor);
          if (block_rows == 0) block_rows = compptr->v_samp_factor;
        }
        inverse_DCT = cinfo->idct->inverse_DCT[ci];
        output_ptr = output_buf[ci];
        /* Loop over all DCT blocks to be processed. */
        for (block_row = 0; block_row < block_rows; block_row++) {
          buffer_ptr = buffer[block_row];
          output_col = 0;
          for (block_num = 0; block_num < compptr->width_in_blocks; block_num++) {
    	(*inverse_DCT) (cinfo, compptr, (JCOEFPTR) buffer_ptr,
    			output_ptr, output_col);
    	buffer_ptr++;
    	output_col += compptr->DCT_h_scaled_size;
          }
          output_ptr += compptr->DCT_v_scaled_size;
        }
      }

      if (++(cinfo->output_iMCU_row) <= last_iMCU_row)
        return JPEG_ROW_COMPLETED;
      return JPEG_SCAN_COMPLETED;
    }

    #endif /* D_MULTISCAN_FILES_SUPPORTED */

    #ifdef BLOCK_SMOOTHING_SUPPORTED

    /*
     * This code applies interblock smoothing as described by section K.8
     * of the JPEG standard: the first 5 AC coefficients are estimated from
     * the DC values of a DCT block and its 8 neighboring blocks.
     * We apply smoothing only for progressive JPEG decoding, and only if
     * the coefficients it can estimate are not yet known to full precision.
     */

    /* Natural-order array positions of the first 5 zigzag-order coefficients */
    #define Q01_POS  1
    #define Q10_POS  8
    #define Q20_POS  16
    #define Q11_POS  9
    #define Q02_POS  2

    /*
     * Determine whether block smoothing is applicable and safe.
     * We also latch the current states of the coef_bits[] entries for the
     * AC coefficients; otherwise, if the input side of the decompressor
     * advances into a new scan, we might think the coefficients are known
     * more accurately than they really are.
     */

    LOCAL(boolean)
    smoothing_ok (j_decompress_ptr cinfo)
    {
      my_coef_ptr coef = (my_coef_ptr) cinfo->coef;
      boolean smoothing_useful = FALSE;
      int ci, coefi;
      jpeg_component_info *compptr;
      JQUANT_TBL * qtable;
      int * coef_bits;
      int * coef_bits_latch;

      if (! cinfo->progressive_mode || cinfo->coef_bits == NULL)
        return FALSE;

      /* Allocate latch area if not already done */
      if (coef->coef_bits_latch == NULL)
        coef->coef_bits_latch = (int *) (*cinfo->mem->alloc_small)
          ((j_common_ptr) cinfo, JPOOL_IMAGE,
           cinfo->num_components * (SAVED_COEFS * SIZEOF(int)));
      coef_bits_latch = coef->coef_bits_latch;

      for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
           ci++, compptr++) {
        /* All components' quantization values must already be latched. */
        if ((qtable = compptr->quant_table) == NULL)
          return FALSE;
        /* Verify DC & first 5 AC quantizers are nonzero to avoid zero-divide. */
        if (qtable->quantval[0] == 0 ||
    	qtable->quantval[Q01_POS] == 0 ||
    	qtable->quantval[Q10_POS] == 0 ||
    	qtable->quantval[Q20_POS] == 0 ||
    	qtable->quantval[Q11_POS] == 0 ||
    	qtable->quantval[Q02_POS] == 0)
          return FALSE;
        /* DC values must be at least partly known for all components. */
        coef_bits = cinfo->coef_bits[ci];
        if (coef_bits[0] < 0)
          return FALSE;
        /* Block smoothing is helpful if some AC coefficients remain inaccurate. */
        for (coefi = 1; coefi <= 5; coefi++) {
          coef_bits_latch[coefi] = coef_bits[coefi];
          if (coef_bits[coefi] != 0)
    	smoothing_useful = TRUE;
        }
        coef_bits_latch += SAVED_COEFS;
      }

      return smoothing_useful;
    }

    /*
     * Variant of decompress_data for use when doing block smoothing.
     */

    METHODDEF(int)
    decompress_smooth_data (j_decompress_ptr cinfo, JSAMPIMAGE output_buf)
    {
      my_coef_ptr coef = (my_coef_ptr) cinfo->coef;
      JDIMENSION last_iMCU_row = cinfo->total_iMCU_rows - 1;
      JDIMENSION block_num, last_block_column;
      int ci, block_row, block_rows, access_rows;
      JBLOCKARRAY buffer;
      JBLOCKROW buffer_ptr, prev_block_row, next_block_row;
      JSAMPARRAY output_ptr;
      JDIMENSION output_col;
      jpeg_component_info *compptr;
      inverse_DCT_method_ptr inverse_DCT;
      boolean first_row, last_row;
      JBLOCK workspace;
      int *coef_bits;
      JQUANT_TBL *quanttbl;
      INT32 Q00,Q01,Q02,Q10,Q11,Q20, num;
      int DC1,DC2,DC3,DC4,DC5,DC6,DC7,DC8,DC9;
      int Al, pred;

      /* Force some input to be done if we are getting ahead of the input. */
      while (cinfo->input_scan_number <= cinfo->output_scan_number &&
    	 ! cinfo->inputctl->eoi_reached) {
        if (cinfo->input_scan_number == cinfo->output_scan_number) {
          /* If input is working on current scan, we ordinarily want it to
           * have completed the current row.  But if input scan is DC,
           * we want it to keep one row ahead so that next block row's DC
           * values are up to date.
           */
          JDIMENSION delta = (cinfo->Ss == 0) ? 1 : 0;
          if (cinfo->input_iMCU_row > cinfo->output_iMCU_row+delta)
    	break;
        }
        if ((*cinfo->inputctl->consume_input)(cinfo) == JPEG_SUSPENDED)
          return JPEG_SUSPENDED;
      }

      /* OK, output from the virtual arrays. */
      for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
           ci++, compptr++) {
        /* Don't bother to IDCT an uninteresting component. */
        if (! compptr->component_needed)
          continue;
        /* Count non-dummy DCT block rows in this iMCU row. */
        if (cinfo->output_iMCU_row < last_iMCU_row) {
          block_rows = compptr->v_samp_factor;
          access_rows = block_rows * 2; /* this and next iMCU row */
          last_row = FALSE;
        } else {
          /* NB: can't use last_row_height here; it is input-side-dependent! */
          block_rows = (int) (compptr->height_in_blocks % compptr->v_samp_factor);
          if (block_rows == 0) block_rows = compptr->v_samp_factor;
          access_rows = block_rows; /* this iMCU row only */
          last_row = TRUE;
        }
        /* Align the virtual buffer for this component. */
        if (cinfo->output_iMCU_row > 0) {
          access_rows += compptr->v_samp_factor; /* prior iMCU row too */
          buffer = (*cinfo->mem->access_virt_barray)
    	((j_common_ptr) cinfo, coef->whole_image[ci],
    	 (cinfo->output_iMCU_row - 1) * compptr->v_samp_factor,
    	 (JDIMENSION) access_rows, FALSE);
          buffer += compptr->v_samp_factor;	/* point to current iMCU row */
          first_row = FALSE;
        } else {
          buffer = (*cinfo->mem->access_virt_barray)
    	((j_common_ptr) cinfo, coef->whole_image[ci],
    	 (JDIMENSION) 0, (JDIMENSION) access_rows, FALSE);
          first_row = TRUE;
        }
        /* Fetch component-dependent info */
        coef_bits = coef->coef_bits_latch + (ci * SAVED_COEFS);
        quanttbl = compptr->quant_table;
        Q00 = quanttbl->quantval[0];
        Q01 = quanttbl->quantval[Q01_POS];
        Q10 = quanttbl->quantval[Q10_POS];
        Q20 = quanttbl->quantval[Q20_POS];
        Q11 = quanttbl->quantval[Q11_POS];
        Q02 = quanttbl->quantval[Q02_POS];
        inverse_DCT = cinfo->idct->inverse_DCT[ci];
        output_ptr = output_buf[ci];
        /* Loop over all DCT blocks to be processed. */
        for (block_row = 0; block_row < block_rows; block_row++) {
          buffer_ptr = buffer[block_row];
          if (first_row && block_row == 0)
    	prev_block_row = buffer_ptr;
          else
    	prev_block_row = buffer[block_row-1];
          if (last_row && block_row == block_rows-1)
    	next_block_row = buffer_ptr;
          else
    	next_block_row = buffer[block_row+1];
          /* We fetch the surrounding DC values using a sliding-register approach.
           * Initialize all nine here so as to do the right thing on narrow pics.
           */
          DC1 = DC2 = DC3 = (int) prev_block_row[0][0];
          DC4 = DC5 = DC6 = (int) buffer_ptr[0][0];
          DC7 = DC8 = DC9 = (int) next_block_row[0][0];
          output_col = 0;
          last_block_column = compptr->width_in_blocks - 1;
          for (block_num = 0; block_num <= last_block_column; block_num++) {
    	/* Fetch current DCT block into workspace so we can modify it. */
    	jcopy_block_row(buffer_ptr, (JBLOCKROW) workspace, (JDIMENSION) 1);
    	/* Update DC values */
    	if (block_num < last_block_column) {
    	  DC3 = (int) prev_block_row[1][0];
    	  DC6 = (int) buffer_ptr[1][0];
    	  DC9 = (int) next_block_row[1][0];
    	}
    	/* Compute coefficient estimates per K.8.
    	 * An estimate is applied only if coefficient is still zero,
    	 * and is not known to be fully accurate.
    	 */
    	/* AC01 */
    	if ((Al=coef_bits[1]) != 0 && workspace[1] == 0) {
    	  num = 36 * Q00 * (DC4 - DC6);
    	  if (num >= 0) {
    	    pred = (int) (((Q01<<7) + num) / (Q01<<8));
    	    if (Al > 0 && pred >= (1<<Al))
    	      pred = (1<<Al)-1;
    	  } else {
    	    pred = (int) (((Q01<<7) - num) / (Q01<<8));
    	    if (Al > 0 && pred >= (1<<Al))
    	      pred = (1<<Al)-1;
    	    pred = -pred;
    	  }
    	  workspace[1] = (JCOEF) pred;
    	}
    	/* AC10 */
    	if ((Al=coef_bits[2]) != 0 && workspace[8] == 0) {
    	  num = 36 * Q00 * (DC2 - DC8);
    	  if (num >= 0) {
    	    pred = (int) (((Q10<<7) + num) / (Q10<<8));
    	    if (Al > 0 && pred >= (1<<Al))
    	      pred = (1<<Al)-1;
    	  } else {
    	    pred = (int) (((Q10<<7) - num) / (Q10<<8));
    	    if (Al > 0 && pred >= (1<<Al))
    	      pred = (1<<Al)-1;
    	    pred = -pred;
    	  }
    	  workspace[8] = (JCOEF) pred;
    	}
    	/* AC20 */
    	if ((Al=coef_bits[3]) != 0 && workspace[16] == 0) {
    	  num = 9 * Q00 * (DC2 + DC8 - 2*DC5);
    	  if (num >= 0) {
    	    pred = (int) (((Q20<<7) + num) / (Q20<<8));
    	    if (Al > 0 && pred >= (1<<Al))
    	      pred = (1<<Al)-1;
    	  } else {
    	    pred = (int) (((Q20<<7) - num) / (Q20<<8));
    	    if (Al > 0 && pred >= (1<<Al))
    	      pred = (1<<Al)-1;
    	    pred = -pred;
    	  }
    	  workspace[16] = (JCOEF) pred;
    	}
    	/* AC11 */
    	if ((Al=coef_bits[4]) != 0 && workspace[9] == 0) {
    	  num = 5 * Q00 * (DC1 - DC3 - DC7 + DC9);
    	  if (num >= 0) {
    	    pred = (int) (((Q11<<7) + num) / (Q11<<8));
    	    if (Al > 0 && pred >= (1<<Al))
    	      pred = (1<<Al)-1;
    	  } else {
    	    pred = (int) (((Q11<<7) - num) / (Q11<<8));
    	    if (Al > 0 && pred >= (1<<Al))
    	      pred = (1<<Al)-1;
    	    pred = -pred;
    	  }
    	  workspace[9] = (JCOEF) pred;
    	}
    	/* AC02 */
    	if ((Al=coef_bits[5]) != 0 && workspace[2] == 0) {
    	  num = 9 * Q00 * (DC4 + DC6 - 2*DC5);
    	  if (num >= 0) {
    	    pred = (int) (((Q02<<7) + num) / (Q02<<8));
    	    if (Al > 0 && pred >= (1<<Al))
    	      pred = (1<<Al)-1;
    	  } else {
    	    pred = (int) (((Q02<<7) - num) / (Q02<<8));
    	    if (Al > 0 && pred >= (1<<Al))
    	      pred = (1<<Al)-1;
    	    pred = -pred;
    	  }
    	  workspace[2] = (JCOEF) pred;
    	}
    	/* OK, do the IDCT */
    	(*inverse_DCT) (cinfo, compptr, (JCOEFPTR) workspace,
    			output_ptr, output_col);
    	/* Advance for next column */
    	DC1 = DC2; DC2 = DC3;
    	DC4 = DC5; DC5 = DC6;
    	DC7 = DC8; DC8 = DC9;
    	buffer_ptr++, prev_block_row++, next_block_row++;
    	output_col += compptr->DCT_h_scaled_size;
          }
          output_ptr += compptr->DCT_v_scaled_size;
        }
      }

      if (++(cinfo->output_iMCU_row) <= last_iMCU_row)
        return JPEG_ROW_COMPLETED;
      return JPEG_SCAN_COMPLETED;
    }

    #endif /* BLOCK_SMOOTHING_SUPPORTED */

    /*
     * Initialize coefficient buffer controller.
     */

    GLOBAL(void)
    jinit_d_coef_controller (j_decompress_ptr cinfo, boolean need_full_buffer)
    {
      my_coef_ptr coef;

      if (need_full_buffer) {
    #ifdef D_MULTISCAN_FILES_SUPPORTED
        /* Allocate a full-image virtual array for each component, */
        /* padded to a multiple of samp_factor DCT blocks in each direction. */
        /* Note we ask for a pre-zeroed array. */
        int ci, access_rows;
        jpeg_component_info *compptr;

        coef = (my_coef_ptr) (*cinfo->mem->alloc_small)
          ((j_common_ptr) cinfo, JPOOL_IMAGE,
           SIZEOF(my_coef_controller) - SIZEOF(coef->blk_buffer));
        for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
    	 ci++, compptr++) {
          access_rows = compptr->v_samp_factor;
    #ifdef BLOCK_SMOOTHING_SUPPORTED
          /* If block smoothing could be used, need a bigger window */
          if (cinfo->progressive_mode)
    	access_rows *= 3;
    #endif
          coef->whole_image[ci] = (*cinfo->mem->request_virt_barray)
    	((j_common_ptr) cinfo, JPOOL_IMAGE, TRUE,
    	 (JDIMENSION) jround_up((long) compptr->width_in_blocks,
    				(long) compptr->h_samp_factor),
    	 (JDIMENSION) jround_up((long) compptr->height_in_blocks,
    				(long) compptr->v_samp_factor),
    	 (JDIMENSION) access_rows);
        }
        coef->pub.consume_data = consume_data;
        coef->pub.decompress_data = decompress_data;
        coef->pub.coef_arrays = coef->whole_image; /* link to virtual arrays */
    #else
        ERREXIT(cinfo, JERR_NOT_COMPILED);
    #endif
      } else {
        /* We only need a single-MCU buffer. */
        JBLOCKARRAY blkp;
        JBLOCKROW buffer_ptr;
        int bi;

        coef = (my_coef_ptr) (*cinfo->mem->alloc_small)
          ((j_common_ptr) cinfo, JPOOL_IMAGE, SIZEOF(my_coef_controller));
        buffer_ptr = coef->blk_buffer;
        if (cinfo->lim_Se == 0)	/* DC only case: want to bypass later */
          MEMZERO(buffer_ptr, SIZEOF(coef->blk_buffer));
        blkp = coef->MCU_buffer;
        bi = D_MAX_BLOCKS_IN_MCU;
        do {
          *blkp++ = buffer_ptr++;
        } while (--bi);
        coef->pub.consume_data = dummy_consume_data;
        coef->pub.decompress_data = decompress_onepass;
        coef->pub.coef_arrays = NULL; /* flag for no virtual arrays */
      }

      coef->pub.start_input_pass = start_input_pass;
      coef->pub.start_output_pass = start_output_pass;
    #ifdef BLOCK_SMOOTHING_SUPPORTED
      coef->coef_bits_latch = NULL;
    #endif
      cinfo->coef = &coef->pub;
    }