jddctmgr.c - external/github.com/libjpeg-turbo/libjpeg-turbo - Git at Google

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


 /* Private subobject for this module */

 typedef struct {
   struct jpeg_inverse_dct pub;	/* public fields */

   /* Record the IDCT method type actually selected for each component */
   J_DCT_METHOD real_method[MAX_COMPONENTS];
 } my_idct_controller;

 typedef my_idct_controller * my_idct_ptr;


 /* ZIG[i] is the zigzag-order position of the i'th element of a DCT block */
 /* read in natural order (left to right, top to bottom). */
 static const int ZIG[DCTSIZE2] = {
      0,  1,  5,  6, 14, 15, 27, 28,
      2,  4,  7, 13, 16, 26, 29, 42,
      3,  8, 12, 17, 25, 30, 41, 43,
      9, 11, 18, 24, 31, 40, 44, 53,
     10, 19, 23, 32, 39, 45, 52, 54,
     20, 22, 33, 38, 46, 51, 55, 60,
     21, 34, 37, 47, 50, 56, 59, 61,
     35, 36, 48, 49, 57, 58, 62, 63
 };


 /* 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


 /*
  * Initialize for an input scan.
  *
  * Verify that all referenced Q-tables are present, and set up
  * the multiplier table for each one.
  * With a multiple-scan JPEG file, this is called during each input scan,
  * NOT during the final output pass where the IDCT is actually done.
  * The purpose is to save away the current Q-table contents just in case
  * the encoder changes tables between scans.  This decoder will dequantize
  * any component using the Q-table which was current at the start of the
  * first scan using that component.
  */

 METHODDEF void
 start_input_pass (j_decompress_ptr cinfo)
 {
   my_idct_ptr idct = (my_idct_ptr) cinfo->idct;
   int ci, qtblno, i;
   jpeg_component_info *compptr;
   JQUANT_TBL * qtbl;

   for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
     compptr = cinfo->cur_comp_info[ci];
     qtblno = compptr->quant_tbl_no;
     /* Make sure specified quantization table is present */
     if (qtblno < 0 || qtblno >= NUM_QUANT_TBLS ||
 	cinfo->quant_tbl_ptrs[qtblno] == NULL)
       ERREXIT1(cinfo, JERR_NO_QUANT_TABLE, qtblno);
     qtbl = cinfo->quant_tbl_ptrs[qtblno];
     /* Create multiplier table from quant table, unless we already did so. */
     if (compptr->dct_table != NULL)
       continue;
     switch (idct->real_method[compptr->component_index]) {
 #ifdef PROVIDE_ISLOW_TABLES
     case JDCT_ISLOW:
       {
 	/* For LL&M IDCT method, multipliers are equal to raw quantization
 	 * coefficients, but are stored in natural order as ints.
 	 */
 	ISLOW_MULT_TYPE * ismtbl;
 	compptr->dct_table =
 	  (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
 				      DCTSIZE2 * SIZEOF(ISLOW_MULT_TYPE));
 	ismtbl = (ISLOW_MULT_TYPE *) compptr->dct_table;
 	for (i = 0; i < DCTSIZE2; i++) {
 	  ismtbl[i] = (ISLOW_MULT_TYPE) qtbl->quantval[ZIG[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.  The multipliers are stored in natural order.
 	 */
 	IFAST_MULT_TYPE * ifmtbl;
 #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

 	compptr->dct_table =
 	  (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
 				      DCTSIZE2 * SIZEOF(IFAST_MULT_TYPE));
 	ifmtbl = (IFAST_MULT_TYPE *) compptr->dct_table;
 	for (i = 0; i < DCTSIZE2; i++) {
 	  ifmtbl[i] = (IFAST_MULT_TYPE)
 	    DESCALE(MULTIPLY16V16((INT32) qtbl->quantval[ZIG[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
 	 * The multipliers are stored in natural order.
 	 */
 	FLOAT_MULT_TYPE * fmtbl;
 	int row, col;
 	static const double aanscalefactor[DCTSIZE] = {
 	  1.0, 1.387039845, 1.306562965, 1.175875602,
 	  1.0, 0.785694958, 0.541196100, 0.275899379
 	};

 	compptr->dct_table =
 	  (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
 				      DCTSIZE2 * SIZEOF(FLOAT_MULT_TYPE));
 	fmtbl = (FLOAT_MULT_TYPE *) compptr->dct_table;
 	i = 0;
 	for (row = 0; row < DCTSIZE; row++) {
 	  for (col = 0; col < DCTSIZE; col++) {
 	    fmtbl[i] = (FLOAT_MULT_TYPE)
 	      ((double) qtbl->quantval[ZIG[i]] *
 	       aanscalefactor[row] * aanscalefactor[col]);
 	    i++;
 	  }
 	}
       }
       break;
 #endif
     default:
       ERREXIT(cinfo, JERR_NOT_COMPILED);
       break;
     }
   }
 }


 /*
  * Prepare for an output pass that will actually perform IDCTs.
  *
  * start_input_pass should already have been done for all components
  * of interest; we need only verify that this is true.
  * Note that uninteresting components are not required to have loaded tables.
  * This allows the master controller to stop before reading the whole file
  * if it has obtained the data for the interesting component(s).
  */

 METHODDEF void
 start_output_pass (j_decompress_ptr cinfo)
 {
   jpeg_component_info *compptr;
   int ci;

   for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
        ci++, compptr++) {
     if (! compptr->component_needed)
       continue;
     if (compptr->dct_table == NULL)
       ERREXIT1(cinfo, JERR_NO_QUANT_TABLE, compptr->quant_tbl_no);
   }
 }


 /*
  * 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_input_pass = start_input_pass;
   idct->pub.start_output_pass = start_output_pass;

   for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
        ci++, compptr++) {
     compptr->dct_table = NULL;	/* initialize tables to "not prepared" */
     switch (compptr->DCT_scaled_size) {
 #ifdef IDCT_SCALING_SUPPORTED
     case 1:
       idct->pub.inverse_DCT[ci] = jpeg_idct_1x1;
       idct->real_method[ci] = JDCT_ISLOW; /* jidctred uses islow-style table */
       break;
     case 2:
       idct->pub.inverse_DCT[ci] = jpeg_idct_2x2;
       idct->real_method[ci] = JDCT_ISLOW; /* jidctred uses islow-style table */
       break;
     case 4:
       idct->pub.inverse_DCT[ci] = jpeg_idct_4x4;
       idct->real_method[ci] = JDCT_ISLOW; /* jidctred uses islow-style table */
       break;
 #endif
     case DCTSIZE:
       switch (cinfo->dct_method) {
 #ifdef DCT_ISLOW_SUPPORTED
       case JDCT_ISLOW:
 	idct->pub.inverse_DCT[ci] = jpeg_idct_islow;
 	idct->real_method[ci] = JDCT_ISLOW;
 	break;
 #endif
 #ifdef DCT_IFAST_SUPPORTED
       case JDCT_IFAST:
 	idct->pub.inverse_DCT[ci] = jpeg_idct_ifast;
 	idct->real_method[ci] = JDCT_IFAST;
 	break;
 #endif
 #ifdef DCT_FLOAT_SUPPORTED
       case JDCT_FLOAT:
 	idct->pub.inverse_DCT[ci] = jpeg_idct_float;
 	idct->real_method[ci] = JDCT_FLOAT;
 	break;
 #endif
       default:
 	ERREXIT(cinfo, JERR_NOT_COMPILED);
 	break;
       }
       break;
     default:
       ERREXIT1(cinfo, JERR_BAD_DCTSIZE, compptr->DCT_scaled_size);
       break;
     }
   }
 }
	/*
	* jddctmgr.c
	*
	* Copyright (C) 1994, 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 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 */


	/* Private subobject for this module */

	typedef struct {
	struct jpeg_inverse_dct pub; /* public fields */

	/* Record the IDCT method type actually selected for each component */
	J_DCT_METHOD real_method[MAX_COMPONENTS];
	} my_idct_controller;

	typedef my_idct_controller * my_idct_ptr;


	/* ZIG[i] is the zigzag-order position of the i'th element of a DCT block */
	/* read in natural order (left to right, top to bottom). */
	static const int ZIG[DCTSIZE2] = {
	0, 1, 5, 6, 14, 15, 27, 28,
	2, 4, 7, 13, 16, 26, 29, 42,
	3, 8, 12, 17, 25, 30, 41, 43,
	9, 11, 18, 24, 31, 40, 44, 53,
	10, 19, 23, 32, 39, 45, 52, 54,
	20, 22, 33, 38, 46, 51, 55, 60,
	21, 34, 37, 47, 50, 56, 59, 61,
	35, 36, 48, 49, 57, 58, 62, 63
	};


	/* 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


	/*
	* Initialize for an input scan.
	*
	* Verify that all referenced Q-tables are present, and set up
	* the multiplier table for each one.
	* With a multiple-scan JPEG file, this is called during each input scan,
	* NOT during the final output pass where the IDCT is actually done.
	* The purpose is to save away the current Q-table contents just in case
	* the encoder changes tables between scans. This decoder will dequantize
	* any component using the Q-table which was current at the start of the
	* first scan using that component.
	*/

	METHODDEF void
	start_input_pass (j_decompress_ptr cinfo)
	{
	my_idct_ptr idct = (my_idct_ptr) cinfo->idct;
	int ci, qtblno, i;
	jpeg_component_info *compptr;
	JQUANT_TBL * qtbl;

	for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
	compptr = cinfo->cur_comp_info[ci];
	qtblno = compptr->quant_tbl_no;
	/* Make sure specified quantization table is present */
	if (qtblno < 0 \|\| qtblno >= NUM_QUANT_TBLS \|\|
	cinfo->quant_tbl_ptrs[qtblno] == NULL)
	ERREXIT1(cinfo, JERR_NO_QUANT_TABLE, qtblno);
	qtbl = cinfo->quant_tbl_ptrs[qtblno];
	/* Create multiplier table from quant table, unless we already did so. */
	if (compptr->dct_table != NULL)
	continue;
	switch (idct->real_method[compptr->component_index]) {
	#ifdef PROVIDE_ISLOW_TABLES
	case JDCT_ISLOW:
	{
	/* For LL&M IDCT method, multipliers are equal to raw quantization
	* coefficients, but are stored in natural order as ints.
	*/
	ISLOW_MULT_TYPE * ismtbl;
	compptr->dct_table =
	(*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
	DCTSIZE2 * SIZEOF(ISLOW_MULT_TYPE));
	ismtbl = (ISLOW_MULT_TYPE *) compptr->dct_table;
	for (i = 0; i < DCTSIZE2; i++) {
	ismtbl[i] = (ISLOW_MULT_TYPE) qtbl->quantval[ZIG[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. The multipliers are stored in natural order.
	*/
	IFAST_MULT_TYPE * ifmtbl;
	#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

	compptr->dct_table =
	(*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
	DCTSIZE2 * SIZEOF(IFAST_MULT_TYPE));
	ifmtbl = (IFAST_MULT_TYPE *) compptr->dct_table;
	for (i = 0; i < DCTSIZE2; i++) {
	ifmtbl[i] = (IFAST_MULT_TYPE)
	DESCALE(MULTIPLY16V16((INT32) qtbl->quantval[ZIG[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
	* The multipliers are stored in natural order.
	*/
	FLOAT_MULT_TYPE * fmtbl;
	int row, col;
	static const double aanscalefactor[DCTSIZE] = {
	1.0, 1.387039845, 1.306562965, 1.175875602,
	1.0, 0.785694958, 0.541196100, 0.275899379
	};

	compptr->dct_table =
	(*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
	DCTSIZE2 * SIZEOF(FLOAT_MULT_TYPE));
	fmtbl = (FLOAT_MULT_TYPE *) compptr->dct_table;
	i = 0;
	for (row = 0; row < DCTSIZE; row++) {
	for (col = 0; col < DCTSIZE; col++) {
	fmtbl[i] = (FLOAT_MULT_TYPE)
	((double) qtbl->quantval[ZIG[i]] *
	aanscalefactor[row] * aanscalefactor[col]);
	i++;
	}
	}
	}
	break;
	#endif
	default:
	ERREXIT(cinfo, JERR_NOT_COMPILED);
	break;
	}
	}
	}


	/*
	* Prepare for an output pass that will actually perform IDCTs.
	*
	* start_input_pass should already have been done for all components
	* of interest; we need only verify that this is true.
	* Note that uninteresting components are not required to have loaded tables.
	* This allows the master controller to stop before reading the whole file
	* if it has obtained the data for the interesting component(s).
	*/

	METHODDEF void
	start_output_pass (j_decompress_ptr cinfo)
	{
	jpeg_component_info *compptr;
	int ci;

	for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
	ci++, compptr++) {
	if (! compptr->component_needed)
	continue;
	if (compptr->dct_table == NULL)
	ERREXIT1(cinfo, JERR_NO_QUANT_TABLE, compptr->quant_tbl_no);
	}
	}


	/*
	* 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_input_pass = start_input_pass;
	idct->pub.start_output_pass = start_output_pass;

	for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
	ci++, compptr++) {
	compptr->dct_table = NULL; /* initialize tables to "not prepared" */
	switch (compptr->DCT_scaled_size) {
	#ifdef IDCT_SCALING_SUPPORTED
	case 1:
	idct->pub.inverse_DCT[ci] = jpeg_idct_1x1;
	idct->real_method[ci] = JDCT_ISLOW; /* jidctred uses islow-style table */
	break;
	case 2:
	idct->pub.inverse_DCT[ci] = jpeg_idct_2x2;
	idct->real_method[ci] = JDCT_ISLOW; /* jidctred uses islow-style table */
	break;
	case 4:
	idct->pub.inverse_DCT[ci] = jpeg_idct_4x4;
	idct->real_method[ci] = JDCT_ISLOW; /* jidctred uses islow-style table */
	break;
	#endif
	case DCTSIZE:
	switch (cinfo->dct_method) {
	#ifdef DCT_ISLOW_SUPPORTED
	case JDCT_ISLOW:
	idct->pub.inverse_DCT[ci] = jpeg_idct_islow;
	idct->real_method[ci] = JDCT_ISLOW;
	break;
	#endif
	#ifdef DCT_IFAST_SUPPORTED
	case JDCT_IFAST:
	idct->pub.inverse_DCT[ci] = jpeg_idct_ifast;
	idct->real_method[ci] = JDCT_IFAST;
	break;
	#endif
	#ifdef DCT_FLOAT_SUPPORTED
	case JDCT_FLOAT:
	idct->pub.inverse_DCT[ci] = jpeg_idct_float;
	idct->real_method[ci] = JDCT_FLOAT;
	break;
	#endif
	default:
	ERREXIT(cinfo, JERR_NOT_COMPILED);
	break;
	}
	break;
	default:
	ERREXIT1(cinfo, JERR_BAD_DCTSIZE, compptr->DCT_scaled_size);
	break;
	}
	}
	}