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

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

media/libjpeg/jdmaster.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

 /*
  * jdmaster.c
  *
  * This file was part of the Independent JPEG Group's software:
  * Copyright (C) 1991-1997, Thomas G. Lane.
  * Modified 2002-2009 by Guido Vollbeding.
  * libjpeg-turbo Modifications:
  * Copyright (C) 2009-2011, D. R. Commander.
  * For conditions of distribution and use, see the accompanying README file.
  *
  * This file contains master control logic for the JPEG decompressor.
  * These routines are concerned with selecting the modules to be executed
  * and with determining the number of passes and the work to be done in each
  * pass.
  */
 #define JPEG_INTERNALS
 #include "jinclude.h"
 #include "jpeglib.h"
 #include "jpegcomp.h"
 /* Private state */
 typedef struct {
   struct jpeg_decomp_master pub; /* public fields */
   int pass_number;		/* # of passes completed */
   boolean using_merged_upsample; /* TRUE if using merged upsample/cconvert */
   /* Saved references to initialized quantizer modules,
    * in case we need to switch modes.
    */
   struct jpeg_color_quantizer * quantizer_1pass;
   struct jpeg_color_quantizer * quantizer_2pass;
 } my_decomp_master;
 typedef my_decomp_master * my_master_ptr;
 /*
  * Determine whether merged upsample/color conversion should be used.
  * CRUCIAL: this must match the actual capabilities of jdmerge.c!
  */
 LOCAL(boolean)
 use_merged_upsample (j_decompress_ptr cinfo)
 {
 #ifdef UPSAMPLE_MERGING_SUPPORTED
   /* Merging is the equivalent of plain box-filter upsampling */
   if (cinfo->do_fancy_upsampling || cinfo->CCIR601_sampling)
     return FALSE;
   /* jdmerge.c only supports YCC=>RGB color conversion */
   if (cinfo->jpeg_color_space != JCS_YCbCr || cinfo->num_components != 3 ||
       (cinfo->out_color_space != JCS_RGB &&
       cinfo->out_color_space != JCS_EXT_RGB &&
       cinfo->out_color_space != JCS_EXT_RGBX &&
       cinfo->out_color_space != JCS_EXT_BGR &&
       cinfo->out_color_space != JCS_EXT_BGRX &&
       cinfo->out_color_space != JCS_EXT_XBGR &&
       cinfo->out_color_space != JCS_EXT_XRGB &&
       cinfo->out_color_space != JCS_EXT_RGBA &&
       cinfo->out_color_space != JCS_EXT_BGRA &&
       cinfo->out_color_space != JCS_EXT_ABGR &&
       cinfo->out_color_space != JCS_EXT_ARGB) ||
       cinfo->out_color_components != rgb_pixelsize[cinfo->out_color_space])
     return FALSE;
   /* and it only handles 2h1v or 2h2v sampling ratios */
   if (cinfo->comp_info[0].h_samp_factor != 2 ||
       cinfo->comp_info[1].h_samp_factor != 1 ||
       cinfo->comp_info[2].h_samp_factor != 1 ||
       cinfo->comp_info[0].v_samp_factor >  2 ||
       cinfo->comp_info[1].v_samp_factor != 1 ||
       cinfo->comp_info[2].v_samp_factor != 1)
     return FALSE;
   /* furthermore, it doesn't work if we've scaled the IDCTs differently */
   if (cinfo->comp_info[0]._DCT_scaled_size != cinfo->_min_DCT_scaled_size ||
       cinfo->comp_info[1]._DCT_scaled_size != cinfo->_min_DCT_scaled_size ||
       cinfo->comp_info[2]._DCT_scaled_size != cinfo->_min_DCT_scaled_size)
     return FALSE;
   /* ??? also need to test for upsample-time rescaling, when & if supported */
   return TRUE;			/* by golly, it'll work... */
 #else
   return FALSE;
 #endif
 }
 /*
  * Compute output image dimensions and related values.
  * NOTE: this is exported for possible use by application.
  * Hence it mustn't do anything that can't be done twice.
  */
 #if JPEG_LIB_VERSION >= 80
 GLOBAL(void)
 #else
 LOCAL(void)
 #endif
 jpeg_core_output_dimensions (j_decompress_ptr cinfo)
 /* Do computations that are needed before master selection phase.
  * This function is used for transcoding and full decompression.
  */
 {
 #ifdef IDCT_SCALING_SUPPORTED
   int ci;
   jpeg_component_info *compptr;
   /* Compute actual output image dimensions and DCT scaling choices. */
   if (cinfo->scale_num * DCTSIZE <= cinfo->scale_denom) {
     /* Provide 1/block_size scaling */
     cinfo->output_width = (JDIMENSION)
       jdiv_round_up((long) cinfo->image_width, (long) DCTSIZE);
     cinfo->output_height = (JDIMENSION)
       jdiv_round_up((long) cinfo->image_height, (long) DCTSIZE);
     cinfo->_min_DCT_h_scaled_size = 1;
     cinfo->_min_DCT_v_scaled_size = 1;
   } else if (cinfo->scale_num * DCTSIZE <= cinfo->scale_denom * 2) {
     /* Provide 2/block_size scaling */
     cinfo->output_width = (JDIMENSION)
       jdiv_round_up((long) cinfo->image_width * 2L, (long) DCTSIZE);
     cinfo->output_height = (JDIMENSION)
       jdiv_round_up((long) cinfo->image_height * 2L, (long) DCTSIZE);
     cinfo->_min_DCT_h_scaled_size = 2;
     cinfo->_min_DCT_v_scaled_size = 2;
   } else if (cinfo->scale_num * DCTSIZE <= cinfo->scale_denom * 3) {
     /* Provide 3/block_size scaling */
     cinfo->output_width = (JDIMENSION)
       jdiv_round_up((long) cinfo->image_width * 3L, (long) DCTSIZE);
     cinfo->output_height = (JDIMENSION)
       jdiv_round_up((long) cinfo->image_height * 3L, (long) DCTSIZE);
     cinfo->_min_DCT_h_scaled_size = 3;
     cinfo->_min_DCT_v_scaled_size = 3;
   } else if (cinfo->scale_num * DCTSIZE <= cinfo->scale_denom * 4) {
     /* Provide 4/block_size scaling */
     cinfo->output_width = (JDIMENSION)
       jdiv_round_up((long) cinfo->image_width * 4L, (long) DCTSIZE);
     cinfo->output_height = (JDIMENSION)
       jdiv_round_up((long) cinfo->image_height * 4L, (long) DCTSIZE);
     cinfo->_min_DCT_h_scaled_size = 4;
     cinfo->_min_DCT_v_scaled_size = 4;
   } else if (cinfo->scale_num * DCTSIZE <= cinfo->scale_denom * 5) {
     /* Provide 5/block_size scaling */
     cinfo->output_width = (JDIMENSION)
       jdiv_round_up((long) cinfo->image_width * 5L, (long) DCTSIZE);
     cinfo->output_height = (JDIMENSION)
       jdiv_round_up((long) cinfo->image_height * 5L, (long) DCTSIZE);
     cinfo->_min_DCT_h_scaled_size = 5;
     cinfo->_min_DCT_v_scaled_size = 5;
   } else if (cinfo->scale_num * DCTSIZE <= cinfo->scale_denom * 6) {
     /* Provide 6/block_size scaling */
     cinfo->output_width = (JDIMENSION)
       jdiv_round_up((long) cinfo->image_width * 6L, (long) DCTSIZE);
     cinfo->output_height = (JDIMENSION)
       jdiv_round_up((long) cinfo->image_height * 6L, (long) DCTSIZE);
     cinfo->_min_DCT_h_scaled_size = 6;
     cinfo->_min_DCT_v_scaled_size = 6;
   } else if (cinfo->scale_num * DCTSIZE <= cinfo->scale_denom * 7) {
     /* Provide 7/block_size scaling */
     cinfo->output_width = (JDIMENSION)
       jdiv_round_up((long) cinfo->image_width * 7L, (long) DCTSIZE);
     cinfo->output_height = (JDIMENSION)
       jdiv_round_up((long) cinfo->image_height * 7L, (long) DCTSIZE);
     cinfo->_min_DCT_h_scaled_size = 7;
     cinfo->_min_DCT_v_scaled_size = 7;
   } else if (cinfo->scale_num * DCTSIZE <= cinfo->scale_denom * 8) {
     /* Provide 8/block_size scaling */
     cinfo->output_width = (JDIMENSION)
       jdiv_round_up((long) cinfo->image_width * 8L, (long) DCTSIZE);
     cinfo->output_height = (JDIMENSION)
       jdiv_round_up((long) cinfo->image_height * 8L, (long) DCTSIZE);
     cinfo->_min_DCT_h_scaled_size = 8;
     cinfo->_min_DCT_v_scaled_size = 8;
   } else if (cinfo->scale_num * DCTSIZE <= cinfo->scale_denom * 9) {
     /* Provide 9/block_size scaling */
     cinfo->output_width = (JDIMENSION)
       jdiv_round_up((long) cinfo->image_width * 9L, (long) DCTSIZE);
     cinfo->output_height = (JDIMENSION)
       jdiv_round_up((long) cinfo->image_height * 9L, (long) DCTSIZE);
     cinfo->_min_DCT_h_scaled_size = 9;
     cinfo->_min_DCT_v_scaled_size = 9;
   } else if (cinfo->scale_num * DCTSIZE <= cinfo->scale_denom * 10) {
     /* Provide 10/block_size scaling */
     cinfo->output_width = (JDIMENSION)
       jdiv_round_up((long) cinfo->image_width * 10L, (long) DCTSIZE);
     cinfo->output_height = (JDIMENSION)
       jdiv_round_up((long) cinfo->image_height * 10L, (long) DCTSIZE);
     cinfo->_min_DCT_h_scaled_size = 10;
     cinfo->_min_DCT_v_scaled_size = 10;
   } else if (cinfo->scale_num * DCTSIZE <= cinfo->scale_denom * 11) {
     /* Provide 11/block_size scaling */
     cinfo->output_width = (JDIMENSION)
       jdiv_round_up((long) cinfo->image_width * 11L, (long) DCTSIZE);
     cinfo->output_height = (JDIMENSION)
       jdiv_round_up((long) cinfo->image_height * 11L, (long) DCTSIZE);
     cinfo->_min_DCT_h_scaled_size = 11;
     cinfo->_min_DCT_v_scaled_size = 11;
   } else if (cinfo->scale_num * DCTSIZE <= cinfo->scale_denom * 12) {
     /* Provide 12/block_size scaling */
     cinfo->output_width = (JDIMENSION)
       jdiv_round_up((long) cinfo->image_width * 12L, (long) DCTSIZE);
     cinfo->output_height = (JDIMENSION)
       jdiv_round_up((long) cinfo->image_height * 12L, (long) DCTSIZE);
     cinfo->_min_DCT_h_scaled_size = 12;
     cinfo->_min_DCT_v_scaled_size = 12;
   } else if (cinfo->scale_num * DCTSIZE <= cinfo->scale_denom * 13) {
     /* Provide 13/block_size scaling */
     cinfo->output_width = (JDIMENSION)
       jdiv_round_up((long) cinfo->image_width * 13L, (long) DCTSIZE);
     cinfo->output_height = (JDIMENSION)
       jdiv_round_up((long) cinfo->image_height * 13L, (long) DCTSIZE);
     cinfo->_min_DCT_h_scaled_size = 13;
     cinfo->_min_DCT_v_scaled_size = 13;
   } else if (cinfo->scale_num * DCTSIZE <= cinfo->scale_denom * 14) {
     /* Provide 14/block_size scaling */
     cinfo->output_width = (JDIMENSION)
       jdiv_round_up((long) cinfo->image_width * 14L, (long) DCTSIZE);
     cinfo->output_height = (JDIMENSION)
       jdiv_round_up((long) cinfo->image_height * 14L, (long) DCTSIZE);
     cinfo->_min_DCT_h_scaled_size = 14;
     cinfo->_min_DCT_v_scaled_size = 14;
   } else if (cinfo->scale_num * DCTSIZE <= cinfo->scale_denom * 15) {
     /* Provide 15/block_size scaling */
     cinfo->output_width = (JDIMENSION)
       jdiv_round_up((long) cinfo->image_width * 15L, (long) DCTSIZE);
     cinfo->output_height = (JDIMENSION)
       jdiv_round_up((long) cinfo->image_height * 15L, (long) DCTSIZE);
     cinfo->_min_DCT_h_scaled_size = 15;
     cinfo->_min_DCT_v_scaled_size = 15;
   } else {
     /* Provide 16/block_size scaling */
     cinfo->output_width = (JDIMENSION)
       jdiv_round_up((long) cinfo->image_width * 16L, (long) DCTSIZE);
     cinfo->output_height = (JDIMENSION)
       jdiv_round_up((long) cinfo->image_height * 16L, (long) DCTSIZE);
     cinfo->_min_DCT_h_scaled_size = 16;
     cinfo->_min_DCT_v_scaled_size = 16;
   }
   /* Recompute dimensions of components */
   for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
        ci++, compptr++) {
     compptr->_DCT_h_scaled_size = cinfo->_min_DCT_h_scaled_size;
     compptr->_DCT_v_scaled_size = cinfo->_min_DCT_v_scaled_size;
   }
 #else /* !IDCT_SCALING_SUPPORTED */
   /* Hardwire it to "no scaling" */
   cinfo->output_width = cinfo->image_width;
   cinfo->output_height = cinfo->image_height;
   /* jdinput.c has already initialized DCT_scaled_size,
    * and has computed unscaled downsampled_width and downsampled_height.
    */
 #endif /* IDCT_SCALING_SUPPORTED */
 }
 /*
  * Compute output image dimensions and related values.
  * NOTE: this is exported for possible use by application.
  * Hence it mustn't do anything that can't be done twice.
  * Also note that it may be called before the master module is initialized!
  */
 GLOBAL(void)
 jpeg_calc_output_dimensions (j_decompress_ptr cinfo)
 /* Do computations that are needed before master selection phase */
 {
 #ifdef IDCT_SCALING_SUPPORTED
   int ci;
   jpeg_component_info *compptr;
 #endif
   /* Prevent application from calling me at wrong times */
   if (cinfo->global_state != DSTATE_READY)
     ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
   /* Compute core output image dimensions and DCT scaling choices. */
   jpeg_core_output_dimensions(cinfo);
 #ifdef IDCT_SCALING_SUPPORTED
   /* In selecting the actual DCT scaling for each component, we try to
    * scale up the chroma components via IDCT scaling rather than upsampling.
    * This saves time if the upsampler gets to use 1:1 scaling.
    * Note this code adapts subsampling ratios which are powers of 2.
    */
   for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
        ci++, compptr++) {
     int ssize = cinfo->_min_DCT_scaled_size;
     while (ssize < DCTSIZE &&
 	   ((cinfo->max_h_samp_factor * cinfo->_min_DCT_scaled_size) %
 	    (compptr->h_samp_factor * ssize * 2) == 0) &&
 	   ((cinfo->max_v_samp_factor * cinfo->_min_DCT_scaled_size) %
 	    (compptr->v_samp_factor * ssize * 2) == 0)) {
       ssize = ssize * 2;
     }
 #if JPEG_LIB_VERSION >= 70
     compptr->DCT_h_scaled_size = compptr->DCT_v_scaled_size = ssize;
 #else
     compptr->DCT_scaled_size = ssize;
 #endif
   }
   /* Recompute downsampled dimensions of components;
    * application needs to know these if using raw downsampled data.
    */
   for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
        ci++, compptr++) {
     /* Size in samples, after IDCT scaling */
     compptr->downsampled_width = (JDIMENSION)
       jdiv_round_up((long) cinfo->image_width *
 		    (long) (compptr->h_samp_factor * compptr->_DCT_scaled_size),
 		    (long) (cinfo->max_h_samp_factor * DCTSIZE));
     compptr->downsampled_height = (JDIMENSION)
       jdiv_round_up((long) cinfo->image_height *
 		    (long) (compptr->v_samp_factor * compptr->_DCT_scaled_size),
 		    (long) (cinfo->max_v_samp_factor * DCTSIZE));
   }
 #else /* !IDCT_SCALING_SUPPORTED */
   /* Hardwire it to "no scaling" */
   cinfo->output_width = cinfo->image_width;
   cinfo->output_height = cinfo->image_height;
   /* jdinput.c has already initialized DCT_scaled_size to DCTSIZE,
    * and has computed unscaled downsampled_width and downsampled_height.
    */
 #endif /* IDCT_SCALING_SUPPORTED */
   /* Report number of components in selected colorspace. */
   /* Probably this should be in the color conversion module... */
   switch (cinfo->out_color_space) {
   case JCS_GRAYSCALE:
     cinfo->out_color_components = 1;
     break;
   case JCS_RGB:
   case JCS_EXT_RGB:
   case JCS_EXT_RGBX:
   case JCS_EXT_BGR:
   case JCS_EXT_BGRX:
   case JCS_EXT_XBGR:
   case JCS_EXT_XRGB:
   case JCS_EXT_RGBA:
   case JCS_EXT_BGRA:
   case JCS_EXT_ABGR:
   case JCS_EXT_ARGB:
     cinfo->out_color_components = rgb_pixelsize[cinfo->out_color_space];
     break;
   case JCS_YCbCr:
     cinfo->out_color_components = 3;
     break;
   case JCS_CMYK:
   case JCS_YCCK:
     cinfo->out_color_components = 4;
     break;
   default:			/* else must be same colorspace as in file */
     cinfo->out_color_components = cinfo->num_components;
     break;
   }
   cinfo->output_components = (cinfo->quantize_colors ? 1 :
 			      cinfo->out_color_components);
   /* See if upsampler will want to emit more than one row at a time */
   if (use_merged_upsample(cinfo))
     cinfo->rec_outbuf_height = cinfo->max_v_samp_factor;
   else
     cinfo->rec_outbuf_height = 1;
 }
 /*
  * Several decompression processes need to range-limit values to the range
  * 0..MAXJSAMPLE; the input value may fall somewhat outside this range
  * due to noise introduced by quantization, roundoff error, etc.  These
  * processes are inner loops and need to be as fast as possible.  On most
  * machines, particularly CPUs with pipelines or instruction prefetch,
  * a (subscript-check-less) C table lookup
  *		x = sample_range_limit[x];
  * is faster than explicit tests
  *		if (x < 0)  x = 0;
  *		else if (x > MAXJSAMPLE)  x = MAXJSAMPLE;
  * These processes all use a common table prepared by the routine below.
  *
  * For most steps we can mathematically guarantee that the initial value
  * of x is within MAXJSAMPLE+1 of the legal range, so a table running from
  * -(MAXJSAMPLE+1) to 2*MAXJSAMPLE+1 is sufficient.  But for the initial
  * limiting step (just after the IDCT), a wildly out-of-range value is
  * possible if the input data is corrupt.  To avoid any chance of indexing
  * off the end of memory and getting a bad-pointer trap, we perform the
  * post-IDCT limiting thus:
  *		x = range_limit[x & MASK];
  * where MASK is 2 bits wider than legal sample data, ie 10 bits for 8-bit
  * samples.  Under normal circumstances this is more than enough range and
  * a correct output will be generated; with bogus input data the mask will
  * cause wraparound, and we will safely generate a bogus-but-in-range output.
  * For the post-IDCT step, we want to convert the data from signed to unsigned
  * representation by adding CENTERJSAMPLE at the same time that we limit it.
  * So the post-IDCT limiting table ends up looking like this:
  *   CENTERJSAMPLE,CENTERJSAMPLE+1,...,MAXJSAMPLE,
  *   MAXJSAMPLE (repeat 2*(MAXJSAMPLE+1)-CENTERJSAMPLE times),
  *   0          (repeat 2*(MAXJSAMPLE+1)-CENTERJSAMPLE times),
  *   0,1,...,CENTERJSAMPLE-1
  * Negative inputs select values from the upper half of the table after
  * masking.
  *
  * We can save some space by overlapping the start of the post-IDCT table
  * with the simpler range limiting table.  The post-IDCT table begins at
  * sample_range_limit + CENTERJSAMPLE.
  *
  * Note that the table is allocated in near data space on PCs; it's small
  * enough and used often enough to justify this.
  */
 LOCAL(void)
 prepare_range_limit_table (j_decompress_ptr cinfo)
 /* Allocate and fill in the sample_range_limit table */
 {
   JSAMPLE * table;
   int i;
   table = (JSAMPLE *)
     (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
 		(5 * (MAXJSAMPLE+1) + CENTERJSAMPLE) * SIZEOF(JSAMPLE));
   table += (MAXJSAMPLE+1);	/* allow negative subscripts of simple table */
   cinfo->sample_range_limit = table;
   /* First segment of "simple" table: limit[x] = 0 for x < 0 */
   MEMZERO(table - (MAXJSAMPLE+1), (MAXJSAMPLE+1) * SIZEOF(JSAMPLE));
   /* Main part of "simple" table: limit[x] = x */
   for (i = 0; i <= MAXJSAMPLE; i++)
     table[i] = (JSAMPLE) i;
   table += CENTERJSAMPLE;	/* Point to where post-IDCT table starts */
   /* End of simple table, rest of first half of post-IDCT table */
   for (i = CENTERJSAMPLE; i < 2*(MAXJSAMPLE+1); i++)
     table[i] = MAXJSAMPLE;
   /* Second half of post-IDCT table */
   MEMZERO(table + (2 * (MAXJSAMPLE+1)),
 	  (2 * (MAXJSAMPLE+1) - CENTERJSAMPLE) * SIZEOF(JSAMPLE));
   MEMCOPY(table + (4 * (MAXJSAMPLE+1) - CENTERJSAMPLE),
 	  cinfo->sample_range_limit, CENTERJSAMPLE * SIZEOF(JSAMPLE));
 }
 /*
  * Master selection of decompression modules.
  * This is done once at jpeg_start_decompress time.  We determine
  * which modules will be used and give them appropriate initialization calls.
  * We also initialize the decompressor input side to begin consuming data.
  *
  * Since jpeg_read_header has finished, we know what is in the SOF
  * and (first) SOS markers.  We also have all the application parameter
  * settings.
  */
 LOCAL(void)
 master_selection (j_decompress_ptr cinfo)
 {
   my_master_ptr master = (my_master_ptr) cinfo->master;
   boolean use_c_buffer;
   long samplesperrow;
   JDIMENSION jd_samplesperrow;
   /* Initialize dimensions and other stuff */
   jpeg_calc_output_dimensions(cinfo);
   prepare_range_limit_table(cinfo);
   /* Width of an output scanline must be representable as JDIMENSION. */
   samplesperrow = (long) cinfo->output_width * (long) cinfo->out_color_components;
   jd_samplesperrow = (JDIMENSION) samplesperrow;
   if ((long) jd_samplesperrow != samplesperrow)
     ERREXIT(cinfo, JERR_WIDTH_OVERFLOW);
   /* Initialize my private state */
   master->pass_number = 0;
   master->using_merged_upsample = use_merged_upsample(cinfo);
   /* Color quantizer selection */
   master->quantizer_1pass = NULL;
   master->quantizer_2pass = NULL;
   /* No mode changes if not using buffered-image mode. */
   if (! cinfo->quantize_colors || ! cinfo->buffered_image) {
     cinfo->enable_1pass_quant = FALSE;
     cinfo->enable_external_quant = FALSE;
     cinfo->enable_2pass_quant = FALSE;
   }
   if (cinfo->quantize_colors) {
     if (cinfo->raw_data_out)
       ERREXIT(cinfo, JERR_NOTIMPL);
     /* 2-pass quantizer only works in 3-component color space. */
     if (cinfo->out_color_components != 3) {
       cinfo->enable_1pass_quant = TRUE;
       cinfo->enable_external_quant = FALSE;
       cinfo->enable_2pass_quant = FALSE;
       cinfo->colormap = NULL;
     } else if (cinfo->colormap != NULL) {
       cinfo->enable_external_quant = TRUE;
     } else if (cinfo->two_pass_quantize) {
       cinfo->enable_2pass_quant = TRUE;
     } else {
       cinfo->enable_1pass_quant = TRUE;
     }
     if (cinfo->enable_1pass_quant) {
 #ifdef QUANT_1PASS_SUPPORTED
       jinit_1pass_quantizer(cinfo);
       master->quantizer_1pass = cinfo->cquantize;
 #else
       ERREXIT(cinfo, JERR_NOT_COMPILED);
 #endif
     }
     /* We use the 2-pass code to map to external colormaps. */
     if (cinfo->enable_2pass_quant || cinfo->enable_external_quant) {
 #ifdef QUANT_2PASS_SUPPORTED
       jinit_2pass_quantizer(cinfo);
       master->quantizer_2pass = cinfo->cquantize;
 #else
       ERREXIT(cinfo, JERR_NOT_COMPILED);
 #endif
     }
     /* If both quantizers are initialized, the 2-pass one is left active;
      * this is necessary for starting with quantization to an external map.
      */
   }
   /* Post-processing: in particular, color conversion first */
   if (! cinfo->raw_data_out) {
     if (master->using_merged_upsample) {
 #ifdef UPSAMPLE_MERGING_SUPPORTED
       jinit_merged_upsampler(cinfo); /* does color conversion too */
 #else
       ERREXIT(cinfo, JERR_NOT_COMPILED);
 #endif
     } else {
       jinit_color_deconverter(cinfo);
       jinit_upsampler(cinfo);
     }
     jinit_d_post_controller(cinfo, cinfo->enable_2pass_quant);
   }
   /* Inverse DCT */
   jinit_inverse_dct(cinfo);
   /* Entropy decoding: either Huffman or arithmetic coding. */
   if (cinfo->arith_code) {
 #ifdef D_ARITH_CODING_SUPPORTED
     jinit_arith_decoder(cinfo);
 #else
     ERREXIT(cinfo, JERR_ARITH_NOTIMPL);
 #endif
   } else {
     if (cinfo->progressive_mode) {
 #ifdef D_PROGRESSIVE_SUPPORTED
       jinit_phuff_decoder(cinfo);
 #else
       ERREXIT(cinfo, JERR_NOT_COMPILED);
 #endif
     } else
       jinit_huff_decoder(cinfo);
   }
   /* Initialize principal buffer controllers. */
   use_c_buffer = cinfo->inputctl->has_multiple_scans || cinfo->buffered_image;
   jinit_d_coef_controller(cinfo, use_c_buffer);
   if (! cinfo->raw_data_out)
     jinit_d_main_controller(cinfo, FALSE /* never need full buffer here */);
   /* We can now tell the memory manager to allocate virtual arrays. */
   (*cinfo->mem->realize_virt_arrays) ((j_common_ptr) cinfo);
   /* Initialize input side of decompressor to consume first scan. */
   (*cinfo->inputctl->start_input_pass) (cinfo);
 #ifdef D_MULTISCAN_FILES_SUPPORTED
   /* If jpeg_start_decompress will read the whole file, initialize
    * progress monitoring appropriately.  The input step is counted
    * as one pass.
    */
   if (cinfo->progress != NULL && ! cinfo->buffered_image &&
       cinfo->inputctl->has_multiple_scans) {
     int nscans;
     /* Estimate number of scans to set pass_limit. */
     if (cinfo->progressive_mode) {
       /* Arbitrarily estimate 2 interleaved DC scans + 3 AC scans/component. */
       nscans = 2 + 3 * cinfo->num_components;
     } else {
       /* For a nonprogressive multiscan file, estimate 1 scan per component. */
       nscans = cinfo->num_components;
     }
     cinfo->progress->pass_counter = 0L;
     cinfo->progress->pass_limit = (long) cinfo->total_iMCU_rows * nscans;
     cinfo->progress->completed_passes = 0;
     cinfo->progress->total_passes = (cinfo->enable_2pass_quant ? 3 : 2);
     /* Count the input pass as done */
     master->pass_number++;
   }
 #endif /* D_MULTISCAN_FILES_SUPPORTED */
 }
 /*
  * Per-pass setup.
  * This is called at the beginning of each output pass.  We determine which
  * modules will be active during this pass and give them appropriate
  * start_pass calls.  We also set is_dummy_pass to indicate whether this
  * is a "real" output pass or a dummy pass for color quantization.
  * (In the latter case, jdapistd.c will crank the pass to completion.)
  */
 METHODDEF(void)
 prepare_for_output_pass (j_decompress_ptr cinfo)
 {
   my_master_ptr master = (my_master_ptr) cinfo->master;
   if (master->pub.is_dummy_pass) {
 #ifdef QUANT_2PASS_SUPPORTED
     /* Final pass of 2-pass quantization */
     master->pub.is_dummy_pass = FALSE;
     (*cinfo->cquantize->start_pass) (cinfo, FALSE);
     (*cinfo->post->start_pass) (cinfo, JBUF_CRANK_DEST);
     (*cinfo->main->start_pass) (cinfo, JBUF_CRANK_DEST);
 #else
     ERREXIT(cinfo, JERR_NOT_COMPILED);
 #endif /* QUANT_2PASS_SUPPORTED */
   } else {
     if (cinfo->quantize_colors && cinfo->colormap == NULL) {
       /* Select new quantization method */
       if (cinfo->two_pass_quantize && cinfo->enable_2pass_quant) {
 	cinfo->cquantize = master->quantizer_2pass;
 	master->pub.is_dummy_pass = TRUE;
       } else if (cinfo->enable_1pass_quant) {
 	cinfo->cquantize = master->quantizer_1pass;
       } else {
 	ERREXIT(cinfo, JERR_MODE_CHANGE);
       }
     }
     (*cinfo->idct->start_pass) (cinfo);
     (*cinfo->coef->start_output_pass) (cinfo);
     if (! cinfo->raw_data_out) {
       if (! master->using_merged_upsample)
 	(*cinfo->cconvert->start_pass) (cinfo);
       (*cinfo->upsample->start_pass) (cinfo);
       if (cinfo->quantize_colors)
 	(*cinfo->cquantize->start_pass) (cinfo, master->pub.is_dummy_pass);
       (*cinfo->post->start_pass) (cinfo,
 	    (master->pub.is_dummy_pass ? JBUF_SAVE_AND_PASS : JBUF_PASS_THRU));
       (*cinfo->main->start_pass) (cinfo, JBUF_PASS_THRU);
     }
   }
   /* Set up progress monitor's pass info if present */
   if (cinfo->progress != NULL) {
     cinfo->progress->completed_passes = master->pass_number;
     cinfo->progress->total_passes = master->pass_number +
 				    (master->pub.is_dummy_pass ? 2 : 1);
     /* In buffered-image mode, we assume one more output pass if EOI not
      * yet reached, but no more passes if EOI has been reached.
      */
     if (cinfo->buffered_image && ! cinfo->inputctl->eoi_reached) {
       cinfo->progress->total_passes += (cinfo->enable_2pass_quant ? 2 : 1);
     }
   }
 }
 /*
  * Finish up at end of an output pass.
  */
 METHODDEF(void)
 finish_output_pass (j_decompress_ptr cinfo)
 {
   my_master_ptr master = (my_master_ptr) cinfo->master;
   if (cinfo->quantize_colors)
     (*cinfo->cquantize->finish_pass) (cinfo);
   master->pass_number++;
 }
 #ifdef D_MULTISCAN_FILES_SUPPORTED
 /*
  * Switch to a new external colormap between output passes.
  */
 GLOBAL(void)
 jpeg_new_colormap (j_decompress_ptr cinfo)
 {
   my_master_ptr master = (my_master_ptr) cinfo->master;
   /* Prevent application from calling me at wrong times */
   if (cinfo->global_state != DSTATE_BUFIMAGE)
     ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
   if (cinfo->quantize_colors && cinfo->enable_external_quant &&
       cinfo->colormap != NULL) {
     /* Select 2-pass quantizer for external colormap use */
     cinfo->cquantize = master->quantizer_2pass;
     /* Notify quantizer of colormap change */
     (*cinfo->cquantize->new_color_map) (cinfo);
     master->pub.is_dummy_pass = FALSE; /* just in case */
   } else
     ERREXIT(cinfo, JERR_MODE_CHANGE);
 }
 #endif /* D_MULTISCAN_FILES_SUPPORTED */
 /*
  * Initialize master decompression control and select active modules.
  * This is performed at the start of jpeg_start_decompress.
  */
 GLOBAL(void)
 jinit_master_decompress (j_decompress_ptr cinfo)
 {
   my_master_ptr master;
   master = (my_master_ptr)
       (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
 				  SIZEOF(my_decomp_master));
   cinfo->master = (struct jpeg_decomp_master *) master;
   master->pub.prepare_for_output_pass = prepare_for_output_pass;
   master->pub.finish_output_pass = finish_output_pass;
   master->pub.is_dummy_pass = FALSE;
   master_selection(cinfo);
 }

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

media/libjpeg/jdmaster.c