kc3-lang/libjpeg-turbo/jccoefct.c

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• Hash : 19c791cd
  Author :
  Date : 2018-03-08T10:55:20
  

  Improve code formatting consistency
  
  With rare exceptions ...
  - Always separate line continuation characters by one space from
    preceding code.
  - Always use two-space indentation.  Never use tabs.
  - Always use K&R-style conditional blocks.
  - Always surround operators with spaces, except in raw assembly code.
  - Always put a space after, but not before, a comma.
  - Never put a space between type casts and variables/function calls.
  - Never put a space between the function name and the argument list in
    function declarations and prototypes.
  - Always surround braces ('{' and '}') with spaces.
  - Always surround statements (if, for, else, catch, while, do, switch)
    with spaces.
  - Always attach pointer symbols ('*' and '**') to the variable or
    function name.
  - Always precede pointer symbols ('*' and '**') by a space in type
    casts.
  - Use the MIN() macro from jpegint.h within the libjpeg and TurboJPEG
    API libraries (using min() from tjutil.h is still necessary for
    TJBench.)
  - Where it makes sense (particularly in the TurboJPEG code), put a blank
    line after variable declaration blocks.
  - Always separate statements in one-liners by two spaces.
  
  The purpose of this was to ease maintenance on my part and also to make
  it easier for contributors to figure out how to format patch
  submissions.  This was admittedly confusing (even to me sometimes) when
  we had 3 or 4 different style conventions in the same source tree.  The
  new convention is more consistent with the formatting of other OSS code
  bases.
  
  This commit corrects deviations from the chosen formatting style in the
  libjpeg API code and reformats the TurboJPEG API code such that it
  conforms to the same standard.
  
  NOTES:
  - Although it is no longer necessary for the function name in function
    declarations to begin in Column 1 (this was historically necessary
    because of the ansi2knr utility, which allowed libjpeg to be built
    with non-ANSI compilers), we retain that formatting for the libjpeg
    code because it improves readability when using libjpeg's function
    attribute macros (GLOBAL(), etc.)
  - This reformatting project was accomplished with the help of AStyle and
    Uncrustify, although neither was completely up to the task, and thus
    a great deal of manual tweaking was required.  Note to developers of
    code formatting utilities:  the libjpeg-turbo code base is an
    excellent test bed, because AFAICT, it breaks every single one of the
    utilities that are currently available.
  - The legacy (MMX, SSE, 3DNow!) assembly code for i386 has been
    formatted to match the SSE2 code (refer to
    ff5685d5344273df321eb63a005eaae19d2496e3.)  I hadn't intended to
    bother with this, but the Loongson MMI implementation demonstrated
    that there is still academic value to the MMX implementation, as an
    algorithmic model for other 64-bit vector implementations.  Thus, it
    is desirable to improve its readability in the same manner as that of
    the SSE2 implementation.
  

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• jccoefct.c

• /*
   * jccoefct.c
   *
   * This file was part of the Independent JPEG Group's software:
   * Copyright (C) 1994-1997, Thomas G. Lane.
   * It was modified by The libjpeg-turbo Project to include only code and
   * information relevant to libjpeg-turbo.
   * For conditions of distribution and use, see the accompanying README.ijg
   * file.
   *
   * This file contains the coefficient buffer controller for compression.
   * This controller is the top level of the JPEG compressor proper.
   * The coefficient buffer lies between forward-DCT and entropy encoding steps.
   */
  
  #define JPEG_INTERNALS
  #include "jinclude.h"
  #include "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.  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(j_compress_ptr cinfo, JSAMPIMAGE input_buf);
  #ifdef FULL_COEF_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_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] != NULL)
        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] == NULL)
        ERREXIT(cinfo, JERR_BAD_BUFFER_MODE);
      coef->pub.compress_data = compress_first_pass;
      break;
    case JBUF_CRANK_DEST:
      if (coef->whole_image[0] == NULL)
        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 *)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 *)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 *)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 *)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 NULL pointer.
   */
  
  METHODDEF(boolean)
  compress_output(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 */
    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] = NULL; /* flag for no virtual arrays */
    }
  }
  

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