third_party/libjpeg/jddctmgr.c - mojo-tools - Git at Google

 /*
  * jddctmgr.c
  *
  * Copyright (C) 1994-1996, 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 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 */


 /*
  * 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:
       method_ptr = jpeg_idct_2x2;
       method = JDCT_ISLOW;	/* jidctred uses islow-style table */
       break;
     case 4:
       method_ptr = jpeg_idct_4x4;
       method = JDCT_ISLOW;	/* jidctred uses islow-style table */
       break;
 #endif
     case DCTSIZE:
       switch (cinfo->dct_method) {
 #ifdef DCT_ISLOW_SUPPORTED
       case JDCT_ISLOW:
 	method_ptr = jpeg_idct_islow;
 	method = JDCT_ISLOW;
 	break;
 #endif
 #ifdef DCT_IFAST_SUPPORTED
       case JDCT_IFAST:
 	method_ptr = jpeg_idct_ifast;
 	method = JDCT_IFAST;
 	break;
 #endif
 #ifdef DCT_FLOAT_SUPPORTED
       case JDCT_FLOAT:
 	method_ptr = jpeg_idct_float;
 	method = JDCT_FLOAT;
 	break;
 #endif
       default:
 	ERREXIT(cinfo, JERR_NOT_COMPILED);
 	break;
       }
       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;
   }
 }
	/*
	* jddctmgr.c
	*
	* Copyright (C) 1994-1996, 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 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 */


	/*
	* 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:
	method_ptr = jpeg_idct_2x2;
	method = JDCT_ISLOW; /* jidctred uses islow-style table */
	break;
	case 4:
	method_ptr = jpeg_idct_4x4;
	method = JDCT_ISLOW; /* jidctred uses islow-style table */
	break;
	#endif
	case DCTSIZE:
	switch (cinfo->dct_method) {
	#ifdef DCT_ISLOW_SUPPORTED
	case JDCT_ISLOW:
	method_ptr = jpeg_idct_islow;
	method = JDCT_ISLOW;
	break;
	#endif
	#ifdef DCT_IFAST_SUPPORTED
	case JDCT_IFAST:
	method_ptr = jpeg_idct_ifast;
	method = JDCT_IFAST;
	break;
	#endif
	#ifdef DCT_FLOAT_SUPPORTED
	case JDCT_FLOAT:
	method_ptr = jpeg_idct_float;
	method = JDCT_FLOAT;
	break;
	#endif
	default:
	ERREXIT(cinfo, JERR_NOT_COMPILED);
	break;
	}
	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(kPI/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(kPI/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;
	}
	}