/*

 * jddiffct.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 the [un]difference buffer controller for decompression.

 * This controller is the top level of the lossless JPEG decompressor proper.

 * The difference buffer lies between the entropy decoding and

 * prediction/undifferencing steps.  The undifference buffer lies between the

 * prediction/undifferencing and scaling steps.

 *

 * In buffered-image mode, this controller is the interface between

 * input-oriented processing and output-oriented processing.

 */

#define JPEG_INTERNALS

#include "jinclude8.h"

#include "jpeglib8.h"

#include "jlossls8.h"

#ifdef D_LOSSLESS_SUPPORTED

/* Private buffer controller object */

typedef struct {

  /* 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 */

  unsigned int restart_rows_to_go;  /* MCU-rows left in this restart interval */

  unsigned int MCU_vert_offset;     /* counts MCU rows within iMCU row */

  unsigned int MCU_rows_per_iMCU_row;   /* number of such rows needed */

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

  JDIFFARRAY diff_buf[MAX_COMPONENTS];  /* iMCU row of differences */

  JDIFFARRAY undiff_buf[MAX_COMPONENTS]; /* iMCU row of undiff'd samples */

#ifdef D_MULTISCAN_FILES_SUPPORTED

  /* In multi-pass modes, we need a virtual sample array for each component. */

  jvirt_sarray_ptr whole_image[MAX_COMPONENTS];

#endif

} d_diff_controller;

typedef d_diff_controller * d_diff_ptr;

/* Forward declarations */

METHODDEF(int) decompress_data

    JPP((j_decompress_ptr cinfo, JSAMPIMAGE output_buf));

#ifdef D_MULTISCAN_FILES_SUPPORTED

METHODDEF(int) output_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) */

{

  j_lossless_d_ptr losslsd = (j_lossless_d_ptr) cinfo->codec;

  d_diff_ptr diff = (d_diff_ptr) losslsd->diff_private;

  /* 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) {

    diff->MCU_rows_per_iMCU_row = 1;

  } else {

    if (cinfo->input_iMCU_row < (cinfo->total_iMCU_rows-1))

      diff->MCU_rows_per_iMCU_row = (JDIMENSION)cinfo->cur_comp_info[0]->v_samp_factor;

    else

      diff->MCU_rows_per_iMCU_row = (JDIMENSION)cinfo->cur_comp_info[0]->last_row_height;

  }

  diff->MCU_ctr = 0;

  diff->MCU_vert_offset = 0;

}

/*

 * Initialize for an input processing pass.

 */

METHODDEF(void)

start_input_pass (j_decompress_ptr cinfo)

{

  j_lossless_d_ptr losslsd = (j_lossless_d_ptr) cinfo->codec;

  d_diff_ptr diff = (d_diff_ptr) losslsd->diff_private;

  /* Check that the restart interval is an integer multiple of the number 

   * of MCU in an MCU-row.

   */

  if (cinfo->restart_interval % cinfo->MCUs_per_row != 0)

    ERREXIT2(cinfo, JERR_BAD_RESTART,

         (int)cinfo->restart_interval, (int)cinfo->MCUs_per_row);

  /* Initialize restart counter */

  diff->restart_rows_to_go = cinfo->restart_interval / cinfo->MCUs_per_row;

  cinfo->input_iMCU_row = 0;

  start_iMCU_row(cinfo);

}

/*

 * Check for a restart marker & resynchronize decoder, undifferencer.

 * Returns FALSE if must suspend.

 */

METHODDEF(boolean)

process_restart (j_decompress_ptr cinfo)

{

  j_lossless_d_ptr losslsd = (j_lossless_d_ptr) cinfo->codec;

  d_diff_ptr diff = (d_diff_ptr) losslsd->diff_private;

  if (! (*losslsd->entropy_process_restart) (cinfo))

    return FALSE;

  (*losslsd->predict_process_restart) (cinfo);

  /* Reset restart counter */

  diff->restart_rows_to_go = cinfo->restart_interval / cinfo->MCUs_per_row;

  return TRUE;

}

/*

 * Initialize for an output processing pass.

 */

METHODDEF(void)

start_output_pass (j_decompress_ptr cinfo)

{

  cinfo->output_iMCU_row = 0;

}

/*

 * Decompress and return some data in the supplied buffer.

 * 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_data (j_decompress_ptr cinfo, JSAMPIMAGE output_buf)

{

  j_lossless_d_ptr losslsd = (j_lossless_d_ptr) cinfo->codec;

  d_diff_ptr diff = (d_diff_ptr) losslsd->diff_private;

  JDIMENSION MCU_col_num;   /* index of current MCU within row */

  JDIMENSION MCU_count;     /* number of MCUs decoded */

  JDIMENSION last_iMCU_row = cinfo->total_iMCU_rows - 1;

  int comp, ci, row, prev_row;

  unsigned int yoffset;

  jpeg_component_info *compptr;

  /* Loop to process as much as one whole iMCU row */

  for (yoffset = diff->MCU_vert_offset; yoffset < diff->MCU_rows_per_iMCU_row;

       yoffset++) {

    /* Process restart marker if needed; may have to suspend */

    if (cinfo->restart_interval) {

      if (diff->restart_rows_to_go == 0)

    if (! process_restart(cinfo))

      return JPEG_SUSPENDED;

    }

    MCU_col_num = diff->MCU_ctr;

    /* Try to fetch an MCU-row (or remaining portion of suspended MCU-row). */

    MCU_count =

      (*losslsd->entropy_decode_mcus) (cinfo,

                       diff->diff_buf, yoffset, MCU_col_num,

                       cinfo->MCUs_per_row - MCU_col_num);

    if (MCU_count != cinfo->MCUs_per_row - MCU_col_num) {

      /* Suspension forced; update state counters and exit */

      diff->MCU_vert_offset = yoffset;

      diff->MCU_ctr += MCU_count;

      return JPEG_SUSPENDED;

    }

    /* Account for restart interval (no-op if not using restarts) */

    diff->restart_rows_to_go--;

    /* Completed an MCU row, but perhaps not an iMCU row */

    diff->MCU_ctr = 0;

  }

  /*

   * Undifference and scale each scanline of the disassembled MCU-row

   * separately.  We do not process dummy samples at the end of a scanline

   * or dummy rows at the end of the image.

   */

  for (comp = 0; comp < cinfo->comps_in_scan; comp++) {

    compptr = cinfo->cur_comp_info[comp];

    ci = compptr->component_index;

    for (row = 0, prev_row = compptr->v_samp_factor - 1;

     row < (cinfo->input_iMCU_row == last_iMCU_row ?

        compptr->last_row_height : compptr->v_samp_factor);

     prev_row = row, row++) {

      (*losslsd->predict_undifference[ci]) (cinfo, ci,

                        diff->diff_buf[ci][row],

                        diff->undiff_buf[ci][prev_row],

                        diff->undiff_buf[ci][row],

                        compptr->width_in_data_units);

      (*losslsd->scaler_scale) (cinfo, diff->undiff_buf[ci][row],

                output_buf[ci][row],

                compptr->width_in_data_units);

    }

  }

  /* Completed the iMCU row, advance counters for next one.

   *

   * NB: output_data will increment output_iMCU_row.

   * This counter is not needed for the single-pass case

   * or the input side of the multi-pass case.

   */

  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;

}

/*

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

 */

METHODDEF(int)

dummy_consume_data (j_decompress_ptr cinfo)

{

  (void)cinfo;

  return JPEG_SUSPENDED;    /* Always indicate nothing was done */

}

#ifdef D_MULTISCAN_FILES_SUPPORTED

/*

 * Consume input data and store it in the full-image sample buffer.

 * We read as much as one fully interleaved MCU row ("iMCU" row) per call,

 * ie, v_samp_factor 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)

{

  j_lossless_d_ptr losslsd = (j_lossless_d_ptr) cinfo->codec;

  d_diff_ptr diff = (d_diff_ptr) losslsd->diff_private;

  /* JDIMENSION MCU_col_num; */ /* index of current MCU within row */

  /* JDIMENSION MCU_count; */   /* number of MCUs decoded */

  /* JDIMENSION last_iMCU_row = cinfo->total_iMCU_rows - 1; */

  int comp, ci /* , yoffset, row, prev_row */;

  JSAMPARRAY buffer[MAX_COMPONENTS];

  jpeg_component_info *compptr;

  /* Align the virtual buffers for the components used in this scan. */

  for (comp = 0; comp < cinfo->comps_in_scan; comp++) {

    compptr = cinfo->cur_comp_info[comp];

    ci = compptr->component_index;

    buffer[ci] = (*cinfo->mem->access_virt_sarray)

      ((j_common_ptr) cinfo, diff->whole_image[ci],

       cinfo->input_iMCU_row * (JDIMENSION)compptr->v_samp_factor,

       (JDIMENSION) compptr->v_samp_factor, TRUE);

  }

  return decompress_data(cinfo, buffer);

}

/*

 * Output some data from the full-image buffer sample 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)

output_data (j_decompress_ptr cinfo, JSAMPIMAGE output_buf)

{

  j_lossless_d_ptr losslsd = (j_lossless_d_ptr) cinfo->codec;

  d_diff_ptr diff = (d_diff_ptr) losslsd->diff_private;

  JDIMENSION last_iMCU_row = cinfo->total_iMCU_rows - 1;

  int ci, samp_rows, row;

  JSAMPARRAY buffer;

  jpeg_component_info *compptr;

  /* 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++) {

    /* Align the virtual buffer for this component. */

    buffer = (*cinfo->mem->access_virt_sarray)

      ((j_common_ptr) cinfo, diff->whole_image[ci],

       cinfo->output_iMCU_row * (JDIMENSION)compptr->v_samp_factor,

       (JDIMENSION) compptr->v_samp_factor, FALSE);

    if (cinfo->output_iMCU_row < last_iMCU_row)

      samp_rows = compptr->v_samp_factor;

    else {

      /* NB: can't use last_row_height here; it is input-side-dependent! */

      samp_rows = (int)compptr->height_in_data_units % compptr->v_samp_factor;

      if (samp_rows == 0) samp_rows = compptr->v_samp_factor;

    }

    for (row = 0; row < samp_rows; row++) {

      MEMCOPY(output_buf[ci][row], buffer[row],

          compptr->width_in_data_units * SIZEOF(JSAMPLE));

    }

  }

  if (++(cinfo->output_iMCU_row) < cinfo->total_iMCU_rows)

    return JPEG_ROW_COMPLETED;

  return JPEG_SCAN_COMPLETED;

}

#endif /* D_MULTISCAN_FILES_SUPPORTED */

/*

 * Initialize difference buffer controller.

 */

GLOBAL(void)

jinit_d_diff_controller (j_decompress_ptr cinfo, boolean need_full_buffer)

{

  j_lossless_d_ptr losslsd = (j_lossless_d_ptr) cinfo->codec;

  d_diff_ptr diff;

  int ci;

  jpeg_component_info *compptr;

  diff = (d_diff_ptr)

    (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,

                SIZEOF(d_diff_controller));

  losslsd->diff_private = (void *) diff;

  losslsd->diff_start_input_pass = start_input_pass;

  losslsd->pub.start_output_pass = start_output_pass;

  /* Create the [un]difference buffers. */

  for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;

       ci++, compptr++) {

    diff->diff_buf[ci] = (*cinfo->mem->alloc_darray)

      ((j_common_ptr) cinfo, JPOOL_IMAGE,

       (JDIMENSION) jround_up((long) compptr->width_in_data_units,

                  (long) compptr->h_samp_factor),

       (JDIMENSION) compptr->v_samp_factor);

    diff->undiff_buf[ci] = (*cinfo->mem->alloc_darray)

      ((j_common_ptr) cinfo, JPOOL_IMAGE,

       (JDIMENSION) jround_up((long) compptr->width_in_data_units,

                  (long) compptr->h_samp_factor),

       (JDIMENSION) compptr->v_samp_factor);

  }

  if (need_full_buffer) {

#ifdef D_MULTISCAN_FILES_SUPPORTED

    /* Allocate a full-image virtual array for each component. */

    int access_rows;

    for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;

     ci++, compptr++) {

      access_rows = compptr->v_samp_factor;

      diff->whole_image[ci] = (*cinfo->mem->request_virt_sarray)

    ((j_common_ptr) cinfo, JPOOL_IMAGE, FALSE,

     (JDIMENSION) jround_up((long) compptr->width_in_data_units,

                (long) compptr->h_samp_factor),

     (JDIMENSION) jround_up((long) compptr->height_in_data_units,

                (long) compptr->v_samp_factor),

     (JDIMENSION) access_rows);

    }

    losslsd->pub.consume_data = consume_data;

    losslsd->pub.decompress_data = output_data;

#else

    ERREXIT(cinfo, JERR_NOT_COMPILED);

#endif

  } else {

    losslsd->pub.consume_data = dummy_consume_data;

    losslsd->pub.decompress_data = decompress_data;

    diff->whole_image[0] = NULL; /* flag for no virtual arrays */

  }

}

#endif /* D_LOSSLESS_SUPPORTED */