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 /*

  * 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 */

 	  16384, 22725, 21407, 19266, 16384, 12873,  8867,  4520,

 	  22725, 31521, 29692, 26722, 22725, 17855, 12299,  6270,

 	  21407, 29692, 27969, 25172, 21407, 16819, 11585,  5906,

 	  19266, 26722, 25172, 22654, 19266, 15137, 10426,  5315,

 	  16384, 22725, 21407, 19266, 16384, 12873,  8867,  4520,

 	  12873, 17855, 16819, 15137, 12873, 10114,  6967,  3552,

 	   8867, 12299, 11585, 10426,  8867,  6967,  4799,  2446,

 	   4520,  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] = {

 	  1.0, 1.387039845, 1.306562965, 1.175875602,

 	  1.0, 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;

   }

 }