/*

 * jcdiffct.c

 *

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

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

 * Lossless JPEG Modifications:

 * Copyright (C) 1999, Ken Murchison.

 * libjpeg-turbo Modifications:

 * Copyright (C) 2022, 2024, D. R. Commander.

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

 * 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 the prediction/differencing and entropy

 * encoding steps.

 */

#define JPEG_INTERNALS

#include "jinclude.h"

#include "jpeglib.h"

#include "jlossls.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 {

  struct jpeg_c_coef_controller pub; /* public fields */

  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];

} my_diff_controller;

typedef my_diff_controller *my_diff_ptr;

/* Forward declarations */

METHODDEF(boolean) compress_data(j_compress_ptr cinfo, _JSAMPIMAGE input_buf);

#ifdef FULL_SAMP_BUFFER_SUPPORTED

METHODDEF(boolean) compress_first_pass(j_compress_ptr cinfo,

                                       _JSAMPIMAGE input_buf);

METHODDEF(boolean) compress_output(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 */

{

  my_diff_ptr diff = (my_diff_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) {

    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)

{

  my_diff_ptr diff = (my_diff_ptr)cinfo->coef;

  /* Because it is hitching a ride on the jpeg_forward_dct struct,

   * start_pass_lossless() will be called at the start of the initial pass.

   * This ensures that it will be called at the start of the Huffman

   * optimization and output passes as well.

   */

  if (pass_mode == JBUF_CRANK_DEST)

    (*cinfo->fdct->start_pass) (cinfo);

  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);

    diff->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);

    diff->pub._compress_data = compress_first_pass;

    break;

  case JBUF_CRANK_DEST:

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

      ERREXIT(cinfo, JERR_BAD_BUFFER_MODE);

    diff->pub._compress_data = compress_output;

    break;

#endif

  default:

    ERREXIT(cinfo, JERR_BAD_BUFFER_MODE);

    break;

  }

}

#define SWAP_ROWS(rowa, rowb) { \

  _JSAMPROW 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)

{

  my_diff_ptr diff = (my_diff_ptr)cinfo->coef;

  lossless_comp_ptr losslessc = (lossless_comp_ptr)cinfo->fdct;

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

  JDIMENSION MCU_count;         /* number of MCUs encoded */

  JDIMENSION last_iMCU_row = cinfo->total_iMCU_rows - 1;

  int ci, compi, 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 an MCU row, ie,

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

     */

    if (MCU_col_num == 0) {

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

        compptr = cinfo->cur_comp_info[ci];

        compi = 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_blocks % 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++)

              memset(diff->diff_buf[compi][samp_row], 0,

                     jround_up((long)compptr->width_in_blocks,

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

          }

        }

        samps_across = compptr->width_in_blocks;

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

          (*losslessc->scaler_scale) (cinfo,

                                      input_buf[compi][samp_row],

                                      diff->cur_row[compi],

                                      samps_across);

          (*losslessc->predict_difference[compi])

            (cinfo, compi, diff->cur_row[compi], diff->prev_row[compi],

             diff->diff_buf[compi][samp_row], samps_across);

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

        }

      }

    }

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

    MCU_count =

      (*cinfo->entropy->encode_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_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)

{

  my_diff_ptr diff = (my_diff_ptr)cinfo->coef;

  JDIMENSION last_iMCU_row = cinfo->total_iMCU_rows - 1;

  JDIMENSION samps_across;

  int ci, samp_row, samp_rows;

  _JSAMPARRAY buffer;

  jpeg_component_info *compptr;

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

       ci++, compptr++) {

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

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

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

       diff->iMCU_row_num * 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_blocks % compptr->v_samp_factor);

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

    }

    samps_across = compptr->width_in_blocks;

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

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

     * processes a complete row of samples.

     */

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

      memcpy(buffer[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)

{

  my_diff_ptr diff = (my_diff_ptr)cinfo->coef;

  int ci, compi;

  _JSAMPARRAY buffer[MAX_COMPS_IN_SCAN];

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

    compptr = cinfo->cur_comp_info[ci];

    compi = compptr->component_index;

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

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

       diff->iMCU_row_num * 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)

{

  my_diff_ptr diff;

  int ci, row;

  jpeg_component_info *compptr;

#if BITS_IN_JSAMPLE == 8

  if (cinfo->data_precision > BITS_IN_JSAMPLE || cinfo->data_precision < 2)

#else

  if (cinfo->data_precision > BITS_IN_JSAMPLE ||

      cinfo->data_precision < BITS_IN_JSAMPLE - 3)

#endif

    ERREXIT1(cinfo, JERR_BAD_PRECISION, cinfo->data_precision);

  diff = (my_diff_ptr)

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

                                sizeof(my_diff_controller));

  cinfo->coef = (struct jpeg_c_coef_controller *)diff;

  diff->pub.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] = *(_JSAMPARRAY)(*cinfo->mem->alloc_sarray)

      ((j_common_ptr)cinfo, JPOOL_IMAGE,

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

                             (long)compptr->h_samp_factor),

       (JDIMENSION)1);

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

      ((j_common_ptr)cinfo, JPOOL_IMAGE,

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

                             (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] =

      ALLOC_DARRAY(JPOOL_IMAGE,

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

                                         (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++)

      memset(diff->diff_buf[ci][row], 0,

             jround_up((long)compptr->width_in_blocks,

                       (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_blocks,

                               (long)compptr->h_samp_factor),

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

                               (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 */

}

Unexecuted instantiation: j12init_c_diff_controller

Unexecuted instantiation: j16init_c_diff_controller

Unexecuted instantiation: jinit_c_diff_controller

#endif /* C_LOSSLESS_SUPPORTED */