/*

 * jdcoefct.h

 *

 * This file was part of the Independent JPEG Group's software:

 * Copyright (C) 1994-1997, Thomas G. Lane.

 * libjpeg-turbo Modifications:

 * Copyright 2009 Pierre Ossman <ossman@cendio.se> for Cendio AB</ossman@cendio.se>

 * For conditions of distribution and use, see the accompanying README.ijg

 * file.

 */

#define JPEG_INTERNALS

#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 allocate 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];

  /* Temporary workspace for one MCU */

  JCOEF *workspace;

#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

} my_coef_controller;

typedef my_coef_controller *my_coef_ptr;

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;

}