The Tor Browser: media/libjpeg/jccoefct.c@b8a032363ba2 (annotated)

media/libjpeg/jccoefct.c@b8a032363ba2 (annotated)

media/libjpeg/jccoefct.c

Thu, 22 Jan 2015 13:21:57 +0100

author: Michael Schloh von Bennewitz <michael@schloh.com>
date: Thu, 22 Jan 2015 13:21:57 +0100
branch: TOR_BUG_9701
changeset 15: b8a032363ba2
permissions: -rw-r--r--

Incorporate requested changes from Mozilla in review:
https://bugzilla.mozilla.org/show_bug.cgi?id=1123480#c6

 /*
  * jccoefct.c
  *
  * Copyright (C) 1994-1997, 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 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.  (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] != 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 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 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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media/libjpeg/jccoefct.c@b8a032363ba2 (annotated)

media/libjpeg/jccoefct.c