jccoefct.cpp

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/* +------------------------------------------------------------------------+
   |                     Mobile Robot Programming Toolkit (MRPT)            |
   |                          http://www.mrpt.org/                          |
   |                                                                        |
   | Copyright (c) 2005-2017, Individual contributors, see AUTHORS file     |
   | See: http://www.mrpt.org/Authors - All rights reserved.                |
   | Released under BSD License. See details in http://www.mrpt.org/License |
   +------------------------------------------------------------------------+ */

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

/* We use a full-image coefficient buffer when doing Huffman optimization,
 * and also for writing multiple-scan JPEG files.  In all cases, the DCT
 * step is run during the first pass, and subsequent passes need only read
 * the buffered coefficients.
 */
#ifdef ENTROPY_OPT_SUPPORTED
#define FULL_COEF_BUFFER_SUPPORTED
#else
#ifdef C_MULTISCAN_FILES_SUPPORTED
#define FULL_COEF_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 */

        /* For single-pass compression, it's sufficient to buffer just one MCU
         * (although this may prove a bit slow in practice).  We allocate a
         * workspace of C_MAX_BLOCKS_IN_MCU coefficient blocks, and reuse it for
         * each
         * MCU constructed and sent.  (On 80x86, the workspace is FAR even though
         * it's not really very big; this is to keep the module interfaces unchanged
         * when a large coefficient buffer is necessary.)
         * In multi-pass modes, this array points to the current MCU's blocks
         * within the virtual arrays.
         */
        JBLOCKROW MCU_buffer[C_MAX_BLOCKS_IN_MCU];

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

typedef my_coef_controller* my_coef_ptr;

/* Forward declarations */
METHODDEF(boolean)
compress_data JPP((j_compress_ptr cinfo, JSAMPIMAGE input_buf));
#ifdef FULL_COEF_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 */
{
        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 (coef->iMCU_row_num < (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 a processing pass.
 */

METHODDEF(void)
start_pass_coef(j_compress_ptr cinfo, J_BUF_MODE pass_mode)
{
        my_coef_ptr coef = (my_coef_ptr)cinfo->coef;

        coef->iMCU_row_num = 0;
        start_iMCU_row(cinfo);

        switch (pass_mode)
        {
                case JBUF_PASS_THRU:
                        if (coef->whole_image[0] != nullptr)
                                ERREXIT(cinfo, JERR_BAD_BUFFER_MODE);
                        coef->pub.compress_data = compress_data;
                        break;
#ifdef FULL_COEF_BUFFER_SUPPORTED
                case JBUF_SAVE_AND_PASS:
                        if (coef->whole_image[0] == nullptr)
                                ERREXIT(cinfo, JERR_BAD_BUFFER_MODE);
                        coef->pub.compress_data = compress_first_pass;
                        break;
                case JBUF_CRANK_DEST:
                        if (coef->whole_image[0] == nullptr)
                                ERREXIT(cinfo, JERR_BAD_BUFFER_MODE);
                        coef->pub.compress_data = compress_output;
                        break;
#endif
                default:
                        ERREXIT(cinfo, JERR_BAD_BUFFER_MODE);
                        break;
        }
}

/*
 * 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 block 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_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 blkn, bi, ci, yindex, yoffset, blockcnt;
        JDIMENSION ypos, xpos;
        jpeg_component_info* compptr;

        /* Loop to write 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++)
                {
                        /* Determine where data comes from in input_buf and do the DCT
                         * thing.
                         * Each call on forward_DCT processes a horizontal row of DCT blocks
                         * as wide as an MCU; we rely on having allocated the MCU_buffer[]
                         * blocks
                         * sequentially.  Dummy blocks at the right or bottom edge are
                         * filled in
                         * specially.  The data in them does not matter for image
                         * reconstruction,
                         * so we fill them with values that will encode to the smallest
                         * amount of
                         * data, viz: all zeroes in the AC entries, DC entries equal to
                         * previous
                         * block's DC value.  (Thanks to Thomas Kinsman for this idea.)
                         */
                        blkn = 0;
                        for (ci = 0; ci < cinfo->comps_in_scan; ci++)
                        {
                                compptr = cinfo->cur_comp_info[ci];
                                blockcnt = (MCU_col_num < last_MCU_col)
                                                           ? compptr->MCU_width
                                                           : compptr->last_col_width;
                                xpos = MCU_col_num * compptr->MCU_sample_width;
                                ypos =
                                        yoffset * DCTSIZE; /* ypos == (yoffset+yindex) * DCTSIZE */
                                for (yindex = 0; yindex < compptr->MCU_height; yindex++)
                                {
                                        if (coef->iMCU_row_num < last_iMCU_row ||
                                                yoffset + yindex < compptr->last_row_height)
                                        {
                                                (*cinfo->fdct->forward_DCT)(
                                                        cinfo, compptr, input_buf[compptr->component_index],
                                                        coef->MCU_buffer[blkn], ypos, xpos,
                                                        (JDIMENSION)blockcnt);
                                                if (blockcnt < compptr->MCU_width)
                                                {
                                                        /* Create some dummy blocks at the right edge of the
                                                         * image. */
                                                        jzero_far(
                                                                (void FAR*)coef->MCU_buffer[blkn + blockcnt],
                                                                (compptr->MCU_width - blockcnt) *
                                                                        SIZEOF(JBLOCK));
                                                        for (bi = blockcnt; bi < compptr->MCU_width; bi++)
                                                        {
                                                                coef->MCU_buffer[blkn + bi][0][0] =
                                                                        coef->MCU_buffer[blkn + bi - 1][0][0];
                                                        }
                                                }
                                        }
                                        else
                                        {
                                                /* Create a row of dummy blocks at the bottom of the
                                                 * image. */
                                                jzero_far(
                                                        (void FAR*)coef->MCU_buffer[blkn],
                                                        compptr->MCU_width * SIZEOF(JBLOCK));
                                                for (bi = 0; bi < compptr->MCU_width; bi++)
                                                {
                                                        coef->MCU_buffer[blkn + bi][0][0] =
                                                                coef->MCU_buffer[blkn - 1][0][0];
                                                }
                                        }
                                        blkn += compptr->MCU_width;
                                        ypos += DCTSIZE;
                                }
                        }
                        /* Try to write the MCU.  In event of a suspension failure, we will
                         * re-DCT the MCU on restart (a bit inefficient, could be fixed...)
                         */
                        if (!(*cinfo->entropy->encode_mcu)(cinfo, coef->MCU_buffer))
                        {
                                /* Suspension forced; update state counters and exit */
                                coef->MCU_vert_offset = yoffset;
                                coef->mcu_ctr = MCU_col_num;
                                return FALSE;
                        }
                }
                /* Completed an MCU row, but perhaps not an iMCU row */
                coef->mcu_ctr = 0;
        }
        /* Completed the iMCU row, advance counters for next one */
        coef->iMCU_row_num++;
        start_iMCU_row(cinfo);
        return TRUE;
}

#ifdef FULL_COEF_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 block rows for each component in the image.
 * This amount of data is read from the source buffer, DCT'd and quantized,
 * and saved into the virtual arrays.  We also generate suitable dummy blocks
 * as needed at the right and lower edges.  (The dummy blocks are constructed
 * in the virtual arrays, which have been padded appropriately.)  This makes
 * it possible for subsequent passes not to worry about real vs. dummy blocks.
 *
 * We must also emit the data to the entropy encoder.  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 DCT'd and loaded into the virtual arrays in this pass.
 * However, it may be that only a subset of the components are emitted to
 * the entropy encoder 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_coef_ptr coef = (my_coef_ptr)cinfo->coef;
        JDIMENSION last_iMCU_row = cinfo->total_iMCU_rows - 1;
        JDIMENSION blocks_across, MCUs_across, MCUindex;
        int bi, ci, h_samp_factor, block_row, block_rows, ndummy;
        JCOEF lastDC;
        jpeg_component_info* compptr;
        JBLOCKARRAY buffer;
        JBLOCKROW thisblockrow, lastblockrow;

        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_barray)(
                        (j_common_ptr)cinfo, coef->whole_image[ci],
                        coef->iMCU_row_num * compptr->v_samp_factor,
                        (JDIMENSION)compptr->v_samp_factor, TRUE);
                /* Count non-dummy DCT block rows in this iMCU row. */
                if (coef->iMCU_row_num < last_iMCU_row)
                        block_rows = compptr->v_samp_factor;
                else
                {
                        /* NB: can't use last_row_height here, since may not be set! */
                        block_rows =
                                (int)(compptr->height_in_blocks % compptr->v_samp_factor);
                        if (block_rows == 0) block_rows = compptr->v_samp_factor;
                }
                blocks_across = compptr->width_in_blocks;
                h_samp_factor = compptr->h_samp_factor;
                /* Count number of dummy blocks to be added at the right margin. */
                ndummy = (int)(blocks_across % h_samp_factor);
                if (ndummy > 0) ndummy = h_samp_factor - ndummy;
                /* Perform DCT for all non-dummy blocks in this iMCU row.  Each call
                 * on forward_DCT processes a complete horizontal row of DCT blocks.
                 */
                for (block_row = 0; block_row < block_rows; block_row++)
                {
                        thisblockrow = buffer[block_row];
                        (*cinfo->fdct->forward_DCT)(
                                cinfo, compptr, input_buf[ci], thisblockrow,
                                (JDIMENSION)(block_row * DCTSIZE), (JDIMENSION)0,
                                blocks_across);
                        if (ndummy > 0)
                        {
                                /* Create dummy blocks at the right edge of the image. */
                                thisblockrow += blocks_across; /* => first dummy block */
                                jzero_far((void FAR*)thisblockrow, ndummy * SIZEOF(JBLOCK));
                                lastDC = thisblockrow[-1][0];
                                for (bi = 0; bi < ndummy; bi++)
                                {
                                        thisblockrow[bi][0] = lastDC;
                                }
                        }
                }
                /* If at end of image, create dummy block rows as needed.
                 * The tricky part here is that within each MCU, we want the DC values
                 * of the dummy blocks to match the last real block's DC value.
                 * This squeezes a few more bytes out of the resulting file...
                 */
                if (coef->iMCU_row_num == last_iMCU_row)
                {
                        blocks_across += ndummy; /* include lower right corner */
                        MCUs_across = blocks_across / h_samp_factor;
                        for (block_row = block_rows; block_row < compptr->v_samp_factor;
                                 block_row++)
                        {
                                thisblockrow = buffer[block_row];
                                lastblockrow = buffer[block_row - 1];
                                jzero_far(
                                        (void FAR*)thisblockrow,
                                        (size_t)(blocks_across * SIZEOF(JBLOCK)));
                                for (MCUindex = 0; MCUindex < MCUs_across; MCUindex++)
                                {
                                        lastDC = lastblockrow[h_samp_factor - 1][0];
                                        for (bi = 0; bi < h_samp_factor; bi++)
                                        {
                                                thisblockrow[bi][0] = lastDC;
                                        }
                                        thisblockrow +=
                                                h_samp_factor; /* advance to next MCU in row */
                                        lastblockrow += h_samp_factor;
                                }
                        }
                }
        }
        /* 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 entropy encoder, 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 block rows for each component in the scan.
 * The data is obtained from the virtual arrays and fed to the entropy coder.
 * Returns TRUE if the iMCU row is completed, FALSE if suspended.
 *
 * NB: input_buf is ignored; it is likely to be a nullptr pointer.
 */

METHODDEF(boolean)
compress_output(j_compress_ptr cinfo, JSAMPIMAGE)
{
        my_coef_ptr coef = (my_coef_ptr)cinfo->coef;
        JDIMENSION MCU_col_num; /* index of current MCU within row */
        int blkn, ci, xindex, yindex, yoffset;
        JDIMENSION start_col;
        JBLOCKARRAY buffer[MAX_COMPS_IN_SCAN];
        JBLOCKROW buffer_ptr;
        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];
                buffer[ci] = (*cinfo->mem->access_virt_barray)(
                        (j_common_ptr)cinfo, coef->whole_image[compptr->component_index],
                        coef->iMCU_row_num * compptr->v_samp_factor,
                        (JDIMENSION)compptr->v_samp_factor, FALSE);
        }

        /* 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 */
                        blkn = 0; /* index of 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][yindex + yoffset] + start_col;
                                        for (xindex = 0; xindex < compptr->MCU_width; xindex++)
                                        {
                                                coef->MCU_buffer[blkn++] = buffer_ptr++;
                                        }
                                }
                        }
                        /* Try to write the MCU. */
                        if (!(*cinfo->entropy->encode_mcu)(cinfo, coef->MCU_buffer))
                        {
                                /* Suspension forced; update state counters and exit */
                                coef->MCU_vert_offset = yoffset;
                                coef->mcu_ctr = MCU_col_num;
                                return FALSE;
                        }
                }
                /* Completed an MCU row, but perhaps not an iMCU row */
                coef->mcu_ctr = 0;
        }
        /* Completed the iMCU row, advance counters for next one */
        coef->iMCU_row_num++;
        start_iMCU_row(cinfo);
        return TRUE;
}

#endif /* FULL_COEF_BUFFER_SUPPORTED */

/*
 * Initialize coefficient buffer controller.
 */

GLOBAL(void)
jinit_c_coef_controller(j_compress_ptr cinfo, boolean need_full_buffer)
{
        my_coef_ptr coef;

        coef = (my_coef_ptr)(*cinfo->mem->alloc_small)(
                (j_common_ptr)cinfo, JPOOL_IMAGE, SIZEOF(my_coef_controller));
        cinfo->coef = (struct jpeg_c_coef_controller*)coef;
        coef->pub.start_pass = start_pass_coef;

        /* Create the coefficient buffer. */
        if (need_full_buffer)
        {
#ifdef FULL_COEF_BUFFER_SUPPORTED
                /* Allocate a full-image virtual array for each component, */
                /* padded to a multiple of samp_factor DCT blocks in each direction. */
                int ci;
                jpeg_component_info* compptr;

                for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
                         ci++, compptr++)
                {
                        coef->whole_image[ci] = (*cinfo->mem->request_virt_barray)(
                                (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
        {
                /* We only need a single-MCU buffer. */
                JBLOCKROW buffer;
                int i;

                buffer = (JBLOCKROW)(*cinfo->mem->alloc_large)(
                        (j_common_ptr)cinfo, JPOOL_IMAGE,
                        C_MAX_BLOCKS_IN_MCU * SIZEOF(JBLOCK));
                for (i = 0; i < C_MAX_BLOCKS_IN_MCU; i++)
                {
                        coef->MCU_buffer[i] = buffer + i;
                }
                coef->whole_image[0] = nullptr; /* flag for no virtual arrays */
        }
}