/*

 * jcdiffct.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 difference buffer controller for compression.

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

 * The difference buffer lies between prediction/differencing and entropy

 * encoding.

 */

#define JPEG_INTERNALS

#include "jinclude8.h"

#include "jpeglib8.h"

#include "jlossls8.h"       /* Private declarations for lossless codec */

#ifdef C_LOSSLESS_SUPPORTED

/* We use a full-image sample buffer when doing Huffman optimization,

 * and also for writing multiple-scan JPEG files.  In all cases, the

 * full-image buffer is filled during the first pass, and the scaling,

 * prediction and differencing steps are run during subsequent passes.

 */

#ifdef ENTROPY_OPT_SUPPORTED

#define FULL_SAMP_BUFFER_SUPPORTED

#else

#ifdef C_MULTISCAN_FILES_SUPPORTED

#define FULL_SAMP_BUFFER_SUPPORTED

#endif

#endif

/* Private buffer controller object */

typedef struct {

  JDIMENSION iMCU_row_num;  /* iMCU row # within image */

  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 */

  JSAMPROW cur_row[MAX_COMPONENTS]; /* row of point transformed samples */

  JSAMPROW prev_row[MAX_COMPONENTS];    /* previous row of Pt'd samples */

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

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

  jvirt_sarray_ptr whole_image[MAX_COMPONENTS];

} c_diff_controller;

typedef c_diff_controller * c_diff_ptr;

/* Forward declarations */

METHODDEF(boolean) compress_data

    JPP((j_compress_ptr cinfo, JSAMPIMAGE input_buf));

#ifdef FULL_SAMP_BUFFER_SUPPORTED

METHODDEF(boolean) compress_first_pass

    JPP((j_compress_ptr cinfo, JSAMPIMAGE input_buf));

METHODDEF(boolean) compress_output

    JPP((j_compress_ptr cinfo, JSAMPIMAGE input_buf));

#endif

LOCAL(void)

start_iMCU_row (j_compress_ptr cinfo)

/* Reset within-iMCU-row counters for a new row */

{

  j_lossless_c_ptr losslsc = (j_lossless_c_ptr) cinfo->codec;

  c_diff_ptr diff = (c_diff_ptr) losslsc->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 (diff->iMCU_row_num < (cinfo->total_iMCU_rows-1))

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

    else

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

  }

  diff->mcu_ctr = 0;

  diff->MCU_vert_offset = 0;

}

/*

 * Initialize for a processing pass.

 */

METHODDEF(void)

start_pass_diff (j_compress_ptr cinfo, J_BUF_MODE pass_mode)

{

  j_lossless_c_ptr losslsc = (j_lossless_c_ptr) cinfo->codec;

  c_diff_ptr diff = (c_diff_ptr) losslsc->diff_private;

  diff->iMCU_row_num = 0;

  start_iMCU_row(cinfo);

  switch (pass_mode) {

  case JBUF_PASS_THRU:

    if (diff->whole_image[0] != NULL)

      ERREXIT(cinfo, JERR_BAD_BUFFER_MODE);

    losslsc->pub.compress_data = compress_data;

    break;

#ifdef FULL_SAMP_BUFFER_SUPPORTED

  case JBUF_SAVE_AND_PASS:

    if (diff->whole_image[0] == NULL)

      ERREXIT(cinfo, JERR_BAD_BUFFER_MODE);

    losslsc->pub.compress_data = compress_first_pass;

    break;

  case JBUF_CRANK_DEST:

    if (diff->whole_image[0] == NULL)

      ERREXIT(cinfo, JERR_BAD_BUFFER_MODE);

    losslsc->pub.compress_data = compress_output;

    break;

#endif

  default:

    ERREXIT(cinfo, JERR_BAD_BUFFER_MODE);

    break;

  }

}

#define SWAP_ROWS(rowa,rowb) {JSAMPROW temp; temp=rowa; rowa=rowb; rowb=temp;}

/*

 * Process some data in the single-pass case.

 * We process the equivalent of one fully interleaved MCU row ("iMCU" row)

 * per call, ie, v_samp_factor rows for each component in the image.

 * Returns TRUE if the iMCU row is completed, FALSE if suspended.

 *

 * NB: input_buf contains a plane for each component in image,

 * which we index according to the component's SOF position.

 */

METHODDEF(boolean)

compress_data (j_compress_ptr cinfo, JSAMPIMAGE input_buf)

{

  j_lossless_c_ptr losslsc = (j_lossless_c_ptr) cinfo->codec;

  c_diff_ptr diff = (c_diff_ptr) losslsc->diff_private;

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

  JDIMENSION MCU_count;     /* number of MCUs encoded */

  /* JDIMENSION last_MCU_col = cinfo->MCUs_per_row - 1; */

  JDIMENSION last_iMCU_row = cinfo->total_iMCU_rows - 1;

  int comp, ci, yoffset, samp_row, samp_rows, samps_across;

  jpeg_component_info *compptr;

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

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

       yoffset++) {

    MCU_col_num = diff->mcu_ctr;

    /* Scale and predict each scanline of the MCU-row separately.

     *

     * Note: We only do this if we are at the start of a MCU-row, ie,

     * we don't want to reprocess a row suspended by the output.

     */

    if (MCU_col_num == 0) {

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

    compptr = cinfo->cur_comp_info[comp];

    ci = compptr->component_index;

    if (diff->iMCU_row_num < last_iMCU_row)

      samp_rows = compptr->v_samp_factor;

    else {

      /* NB: can't use last_row_height here, since may not be set! */

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

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

      else {

        /* Fill dummy difference rows at the bottom edge with zeros, which

         * will encode to the smallest amount of data.

         */

        for (samp_row = samp_rows; samp_row < compptr->v_samp_factor;

         samp_row++)

          MEMZERO(diff->diff_buf[ci][samp_row],

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

                        (long) compptr->h_samp_factor) * SIZEOF(JDIFF));

      }

    }

    samps_across = (int)compptr->width_in_data_units;

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

      (*losslsc->scaler_scale) (cinfo,

                    input_buf[ci][samp_row],

                    diff->cur_row[ci], (JDIMENSION)samps_across);

      (*losslsc->predict_difference[ci]) (cinfo, ci,

                          diff->cur_row[ci],

                          diff->prev_row[ci],

                          diff->diff_buf[ci][samp_row],

                          (JDIMENSION)samps_across);

      SWAP_ROWS(diff->cur_row[ci], diff->prev_row[ci]);

    }

      }

    }

    /* Try to write the MCU-row (or remaining portion of suspended MCU-row). */

    MCU_count =

      (*losslsc->entropy_encode_mcus) (cinfo,

                       diff->diff_buf, (JDIMENSION)yoffset, MCU_col_num,

                       (JDIMENSION)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_col_num;

      return FALSE;

    }

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

    diff->mcu_ctr = 0;

  }

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

  diff->iMCU_row_num++;

  start_iMCU_row(cinfo);

  return TRUE;

}

#ifdef FULL_SAMP_BUFFER_SUPPORTED

/*

 * Process some data in the first pass of a multi-pass case.

 * We process the equivalent of one fully interleaved MCU row ("iMCU" row)

 * per call, ie, v_samp_factor rows for each component in the image.

 * This amount of data is read from the source buffer and saved into the

 * virtual arrays.

 *

 * We must also emit the data to the compressor.  This is conveniently

 * done by calling compress_output() after we've loaded the current strip

 * of the virtual arrays.

 *

 * NB: input_buf contains a plane for each component in image.  All components

 * are loaded into the virtual arrays in this pass.  However, it may be that

 * only a subset of the components are emitted to the compressor during

 * this first pass; be careful about looking at the scan-dependent variables

 * (MCU dimensions, etc).

 */

METHODDEF(boolean)

compress_first_pass (j_compress_ptr cinfo, JSAMPIMAGE input_buf)

{

  j_lossless_c_ptr losslsc = (j_lossless_c_ptr) cinfo->codec;

  c_diff_ptr diff = (c_diff_ptr) losslsc->diff_private;

  JDIMENSION last_iMCU_row = cinfo->total_iMCU_rows - 1;

  JDIMENSION samps_across;

  int ci, samp_row, samp_rows;

  JSAMPARRAY buffer[MAX_COMPONENTS];

  jpeg_component_info *compptr;

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

       ci++, compptr++) {

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

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

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

       diff->iMCU_row_num * (JDIMENSION)compptr->v_samp_factor,

       (JDIMENSION) compptr->v_samp_factor, TRUE);

    /* Count non-dummy sample rows in this iMCU row. */

    if (diff->iMCU_row_num < last_iMCU_row)

      samp_rows = compptr->v_samp_factor;

    else {

      /* NB: can't use last_row_height here, since may not be set! */

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

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

    }

    samps_across = compptr->width_in_data_units;

    /* Perform point transform scaling and prediction/differencing for all

     * non-dummy rows in this iMCU row.  Each call on these functions

     * process a complete row of samples.

     */

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

      MEMCOPY(buffer[ci][samp_row], input_buf[ci][samp_row],

          samps_across * SIZEOF(JSAMPLE));

    }

  }

  /* NB: compress_output will increment iMCU_row_num if successful.

   * A suspension return will result in redoing all the work above next time.

   */

  /* Emit data to the compressor, sharing code with subsequent passes */

  return compress_output(cinfo, input_buf);

}

/*

 * Process some data in subsequent passes of a multi-pass case.

 * We process the equivalent of one fully interleaved MCU row ("iMCU" row)

 * per call, ie, v_samp_factor rows for each component in the scan.

 * The data is obtained from the virtual arrays and fed to the compressor.

 * Returns TRUE if the iMCU row is completed, FALSE if suspended.

 *

 * NB: input_buf is ignored; it is likely to be a NULL pointer.

 */

METHODDEF(boolean)

compress_output (j_compress_ptr cinfo, JSAMPIMAGE input_buf)

{

  (void)input_buf;

  j_lossless_c_ptr losslsc = (j_lossless_c_ptr) cinfo->codec;

  c_diff_ptr diff = (c_diff_ptr) losslsc->diff_private;

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

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

  int comp, ci /* , yoffset */ ;

  JSAMPARRAY buffer[MAX_COMPONENTS];

  jpeg_component_info *compptr;

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

   * NB: during first pass, this is safe only because the buffers will

   * already be aligned properly, so jmemmgr.c won't need to do any I/O.

   */

  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],

       diff->iMCU_row_num * (JDIMENSION)compptr->v_samp_factor,

       (JDIMENSION) compptr->v_samp_factor, FALSE);

  }

  return compress_data(cinfo, buffer);

}

#endif /* FULL_SAMP_BUFFER_SUPPORTED */

/*

 * Initialize difference buffer controller.

 */

GLOBAL(void)

jinit_c_diff_controller (j_compress_ptr cinfo, boolean need_full_buffer)

{

  j_lossless_c_ptr losslsc = (j_lossless_c_ptr) cinfo->codec;

  c_diff_ptr diff;

  int ci, row;

  jpeg_component_info *compptr;

  diff = (c_diff_ptr)

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

                SIZEOF(c_diff_controller));

  losslsc->diff_private = (void *) diff;

  losslsc->diff_start_pass = start_pass_diff;

  /* Create the prediction row buffers. */

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

       ci++, compptr++) {

    diff->cur_row[ci] = *(*cinfo->mem->alloc_sarray)

      ((j_common_ptr) cinfo, JPOOL_IMAGE,

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

                  (long) compptr->h_samp_factor),

       (JDIMENSION) 1);

    diff->prev_row[ci] = *(*cinfo->mem->alloc_sarray)

      ((j_common_ptr) cinfo, JPOOL_IMAGE,

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

                  (long) compptr->h_samp_factor),

       (JDIMENSION) 1);

  }

  /* Create the difference buffer. */

  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);

    /* Prefill difference rows with zeros.  We do this because only actual

     * data is placed in the buffers during prediction/differencing, leaving

     * any dummy differences at the right edge as zeros, which will encode

     * to the smallest amount of data.

     */

    for (row = 0; row < compptr->v_samp_factor; row++)

      MEMZERO(diff->diff_buf[ci][row],

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

                    (long) compptr->h_samp_factor) * SIZEOF(JDIFF));

  }

  /* Create the sample buffer. */

  if (need_full_buffer) {

#ifdef FULL_SAMP_BUFFER_SUPPORTED

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

    /* padded to a multiple of samp_factor differences in each direction. */

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

     ci++, compptr++) {

      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) compptr->v_samp_factor);

    }

#else

    ERREXIT(cinfo, JERR_BAD_BUFFER_MODE);

#endif

  } else

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

}

#endif /* C_LOSSLESS_SUPPORTED */