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

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

media/libjpeg/jddctmgr.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

 /*
  * jddctmgr.c
  *
  * This file was part of the Independent JPEG Group's software:
  * Copyright (C) 1994-1996, Thomas G. Lane.
  * Modified 2002-2010 by Guido Vollbeding.
  * libjpeg-turbo Modifications:
  * Copyright 2009 Pierre Ossman <ossman@cendio.se> for Cendio AB
  * Copyright (C) 2010, D. R. Commander.
  * For conditions of distribution and use, see the accompanying README file.
  *
  * This file contains the inverse-DCT management logic.
  * This code selects a particular IDCT implementation to be used,
  * and it performs related housekeeping chores.  No code in this file
  * is executed per IDCT step, only during output pass setup.
  *
  * Note that the IDCT routines are responsible for performing coefficient
  * dequantization as well as the IDCT proper.  This module sets up the
  * dequantization multiplier table needed by the IDCT routine.
  */
 #define JPEG_INTERNALS
 #include "jinclude.h"
 #include "jpeglib.h"
 #include "jdct.h"		/* Private declarations for DCT subsystem */
 #include "jsimddct.h"
 #include "jpegcomp.h"
 /*
  * The decompressor input side (jdinput.c) saves away the appropriate
  * quantization table for each component at the start of the first scan
  * involving that component.  (This is necessary in order to correctly
  * decode files that reuse Q-table slots.)
  * When we are ready to make an output pass, the saved Q-table is converted
  * to a multiplier table that will actually be used by the IDCT routine.
  * The multiplier table contents are IDCT-method-dependent.  To support
  * application changes in IDCT method between scans, we can remake the
  * multiplier tables if necessary.
  * In buffered-image mode, the first output pass may occur before any data
  * has been seen for some components, and thus before their Q-tables have
  * been saved away.  To handle this case, multiplier tables are preset
  * to zeroes; the result of the IDCT will be a neutral gray level.
  */
 /* Private subobject for this module */
 typedef struct {
   struct jpeg_inverse_dct pub;	/* public fields */
   /* This array contains the IDCT method code that each multiplier table
    * is currently set up for, or -1 if it's not yet set up.
    * The actual multiplier tables are pointed to by dct_table in the
    * per-component comp_info structures.
    */
   int cur_method[MAX_COMPONENTS];
 } my_idct_controller;
 typedef my_idct_controller * my_idct_ptr;
 /* Allocated multiplier tables: big enough for any supported variant */
 typedef union {
   ISLOW_MULT_TYPE islow_array[DCTSIZE2];
 #ifdef DCT_IFAST_SUPPORTED
   IFAST_MULT_TYPE ifast_array[DCTSIZE2];
 #endif
 #ifdef DCT_FLOAT_SUPPORTED
   FLOAT_MULT_TYPE float_array[DCTSIZE2];
 #endif
 } multiplier_table;
 /* The current scaled-IDCT routines require ISLOW-style multiplier tables,
  * so be sure to compile that code if either ISLOW or SCALING is requested.
  */
 #ifdef DCT_ISLOW_SUPPORTED
 #define PROVIDE_ISLOW_TABLES
 #else
 #ifdef IDCT_SCALING_SUPPORTED
 #define PROVIDE_ISLOW_TABLES
 #endif
 #endif
 /*
  * Prepare for an output pass.
  * Here we select the proper IDCT routine for each component and build
  * a matching multiplier table.
  */
 METHODDEF(void)
 start_pass (j_decompress_ptr cinfo)
 {
   my_idct_ptr idct = (my_idct_ptr) cinfo->idct;
   int ci, i;
   jpeg_component_info *compptr;
   int method = 0;
   inverse_DCT_method_ptr method_ptr = NULL;
   JQUANT_TBL * qtbl;
   for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
        ci++, compptr++) {
     /* Select the proper IDCT routine for this component's scaling */
     switch (compptr->_DCT_scaled_size) {
 #ifdef IDCT_SCALING_SUPPORTED
     case 1:
       method_ptr = jpeg_idct_1x1;
       method = JDCT_ISLOW;	/* jidctred uses islow-style table */
       break;
     case 2:
       if (jsimd_can_idct_2x2())
         method_ptr = jsimd_idct_2x2;
       else
         method_ptr = jpeg_idct_2x2;
       method = JDCT_ISLOW;	/* jidctred uses islow-style table */
       break;
     case 3:
       method_ptr = jpeg_idct_3x3;
       method = JDCT_ISLOW;	/* jidctint uses islow-style table */
       break;
     case 4:
       if (jsimd_can_idct_4x4())
         method_ptr = jsimd_idct_4x4;
       else
         method_ptr = jpeg_idct_4x4;
       method = JDCT_ISLOW;	/* jidctred uses islow-style table */
       break;
     case 5:
       method_ptr = jpeg_idct_5x5;
       method = JDCT_ISLOW;	/* jidctint uses islow-style table */
       break;
     case 6:
       method_ptr = jpeg_idct_6x6;
       method = JDCT_ISLOW;	/* jidctint uses islow-style table */
       break;
     case 7:
       method_ptr = jpeg_idct_7x7;
       method = JDCT_ISLOW;	/* jidctint uses islow-style table */
       break;
 #endif
     case DCTSIZE:
       switch (cinfo->dct_method) {
 #ifdef DCT_ISLOW_SUPPORTED
       case JDCT_ISLOW:
 	if (jsimd_can_idct_islow())
 	  method_ptr = jsimd_idct_islow;
 	else
 	  method_ptr = jpeg_idct_islow;
 	method = JDCT_ISLOW;
 	break;
 #endif
 #ifdef DCT_IFAST_SUPPORTED
       case JDCT_IFAST:
 	if (jsimd_can_idct_ifast())
 	  method_ptr = jsimd_idct_ifast;
 	else
 	  method_ptr = jpeg_idct_ifast;
 	method = JDCT_IFAST;
 	break;
 #endif
 #ifdef DCT_FLOAT_SUPPORTED
       case JDCT_FLOAT:
 	if (jsimd_can_idct_float())
 	  method_ptr = jsimd_idct_float;
 	else
 	  method_ptr = jpeg_idct_float;
 	method = JDCT_FLOAT;
 	break;
 #endif
       default:
 	ERREXIT(cinfo, JERR_NOT_COMPILED);
 	break;
       }
       break;
     case 9:
       method_ptr = jpeg_idct_9x9;
       method = JDCT_ISLOW;	/* jidctint uses islow-style table */
       break;
     case 10:
       method_ptr = jpeg_idct_10x10;
       method = JDCT_ISLOW;	/* jidctint uses islow-style table */
       break;
     case 11:
       method_ptr = jpeg_idct_11x11;
       method = JDCT_ISLOW;	/* jidctint uses islow-style table */
       break;
     case 12:
       method_ptr = jpeg_idct_12x12;
       method = JDCT_ISLOW;	/* jidctint uses islow-style table */
       break;
     case 13:
       method_ptr = jpeg_idct_13x13;
       method = JDCT_ISLOW;	/* jidctint uses islow-style table */
       break;
     case 14:
       method_ptr = jpeg_idct_14x14;
       method = JDCT_ISLOW;	/* jidctint uses islow-style table */
       break;
     case 15:
       method_ptr = jpeg_idct_15x15;
       method = JDCT_ISLOW;	/* jidctint uses islow-style table */
       break;
     case 16:
       method_ptr = jpeg_idct_16x16;
       method = JDCT_ISLOW;	/* jidctint uses islow-style table */
       break;
     default:
       ERREXIT1(cinfo, JERR_BAD_DCTSIZE, compptr->_DCT_scaled_size);
       break;
     }
     idct->pub.inverse_DCT[ci] = method_ptr;
     /* Create multiplier table from quant table.
      * However, we can skip this if the component is uninteresting
      * or if we already built the table.  Also, if no quant table
      * has yet been saved for the component, we leave the
      * multiplier table all-zero; we'll be reading zeroes from the
      * coefficient controller's buffer anyway.
      */
     if (! compptr->component_needed || idct->cur_method[ci] == method)
       continue;
     qtbl = compptr->quant_table;
     if (qtbl == NULL)		/* happens if no data yet for component */
       continue;
     idct->cur_method[ci] = method;
     switch (method) {
 #ifdef PROVIDE_ISLOW_TABLES
     case JDCT_ISLOW:
       {
 	/* For LL&M IDCT method, multipliers are equal to raw quantization
 	 * coefficients, but are stored as ints to ensure access efficiency.
 	 */
 	ISLOW_MULT_TYPE * ismtbl = (ISLOW_MULT_TYPE *) compptr->dct_table;
 	for (i = 0; i < DCTSIZE2; i++) {
 	  ismtbl[i] = (ISLOW_MULT_TYPE) qtbl->quantval[i];
 	}
       }
       break;
 #endif
 #ifdef DCT_IFAST_SUPPORTED
     case JDCT_IFAST:
       {
 	/* For AA&N IDCT method, multipliers are equal to quantization
 	 * coefficients scaled by scalefactor[row]*scalefactor[col], where
 	 *   scalefactor[0] = 1
 	 *   scalefactor[k] = cos(k*PI/16) * sqrt(2)    for k=1..7
 	 * For integer operation, the multiplier table is to be scaled by
 	 * IFAST_SCALE_BITS.
 	 */
 	IFAST_MULT_TYPE * ifmtbl = (IFAST_MULT_TYPE *) compptr->dct_table;
 #define CONST_BITS 14
 	static const INT16 aanscales[DCTSIZE2] = {
 	  /* precomputed values scaled up by 14 bits */
 , 22725, 21407, 19266, 16384, 12873,  8867,  4520,
 , 31521, 29692, 26722, 22725, 17855, 12299,  6270,
 , 29692, 27969, 25172, 21407, 16819, 11585,  5906,
 , 26722, 25172, 22654, 19266, 15137, 10426,  5315,
 , 22725, 21407, 19266, 16384, 12873,  8867,  4520,
 , 17855, 16819, 15137, 12873, 10114,  6967,  3552,
 , 12299, 11585, 10426,  8867,  6967,  4799,  2446,
 ,  6270,  5906,  5315,  4520,  3552,  2446,  1247
 	};
 	SHIFT_TEMPS
 	for (i = 0; i < DCTSIZE2; i++) {
 	  ifmtbl[i] = (IFAST_MULT_TYPE)
 	    DESCALE(MULTIPLY16V16((INT32) qtbl->quantval[i],
 				  (INT32) aanscales[i]),
 		    CONST_BITS-IFAST_SCALE_BITS);
 	}
       }
       break;
 #endif
 #ifdef DCT_FLOAT_SUPPORTED
     case JDCT_FLOAT:
       {
 	/* For float AA&N IDCT method, multipliers are equal to quantization
 	 * coefficients scaled by scalefactor[row]*scalefactor[col], where
 	 *   scalefactor[0] = 1
 	 *   scalefactor[k] = cos(k*PI/16) * sqrt(2)    for k=1..7
 	 */
 	FLOAT_MULT_TYPE * fmtbl = (FLOAT_MULT_TYPE *) compptr->dct_table;
 	int row, col;
 	static const double aanscalefactor[DCTSIZE] = {
 .0, 1.387039845, 1.306562965, 1.175875602,
 .0, 0.785694958, 0.541196100, 0.275899379
 	};
 	i = 0;
 	for (row = 0; row < DCTSIZE; row++) {
 	  for (col = 0; col < DCTSIZE; col++) {
 	    fmtbl[i] = (FLOAT_MULT_TYPE)
 	      ((double) qtbl->quantval[i] *
 	       aanscalefactor[row] * aanscalefactor[col]);
 	    i++;
 	  }
 	}
       }
       break;
 #endif
     default:
       ERREXIT(cinfo, JERR_NOT_COMPILED);
       break;
     }
   }
 }
 /*
  * Initialize IDCT manager.
  */
 GLOBAL(void)
 jinit_inverse_dct (j_decompress_ptr cinfo)
 {
   my_idct_ptr idct;
   int ci;
   jpeg_component_info *compptr;
   idct = (my_idct_ptr)
     (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
 				SIZEOF(my_idct_controller));
   cinfo->idct = (struct jpeg_inverse_dct *) idct;
   idct->pub.start_pass = start_pass;
   for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
        ci++, compptr++) {
     /* Allocate and pre-zero a multiplier table for each component */
     compptr->dct_table =
       (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
 				  SIZEOF(multiplier_table));
     MEMZERO(compptr->dct_table, SIZEOF(multiplier_table));
     /* Mark multiplier table not yet set up for any method */
     idct->cur_method[ci] = -1;
   }
 }

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

media/libjpeg/jddctmgr.c