libSBRdec/src/transcendent.h

   1
   2 /* -----------------------------------------------------------------------------------------------------------
   3 Software License for The Fraunhofer FDK AAC Codec Library for Android
   4
   5 © Copyright  1995 - 2013 Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V.
   6   All rights reserved.
   7
   8  1.    INTRODUCTION
   9 The Fraunhofer FDK AAC Codec Library for Android ("FDK AAC Codec") is software that implements
  10 the MPEG Advanced Audio Coding ("AAC") encoding and decoding scheme for digital audio.
  11 This FDK AAC Codec software is intended to be used on a wide variety of Android devices.
  12
  13 AAC's HE-AAC and HE-AAC v2 versions are regarded as today's most efficient general perceptual
  14 audio codecs. AAC-ELD is considered the best-performing full-bandwidth communications codec by
  15 independent studies and is widely deployed. AAC has been standardized by ISO and IEC as part
  16 of the MPEG specifications.
  17
  18 Patent licenses for necessary patent claims for the FDK AAC Codec (including those of Fraunhofer)
  19 may be obtained through Via Licensing (www.vialicensing.com) or through the respective patent owners
  20 individually for the purpose of encoding or decoding bit streams in products that are compliant with
  21 the ISO/IEC MPEG audio standards. Please note that most manufacturers of Android devices already license
  22 these patent claims through Via Licensing or directly from the patent owners, and therefore FDK AAC Codec
  23 software may already be covered under those patent licenses when it is used for those licensed purposes only.
  24
  25 Commercially-licensed AAC software libraries, including floating-point versions with enhanced sound quality,
  26 are also available from Fraunhofer. Users are encouraged to check the Fraunhofer website for additional
  27 applications information and documentation.
  28
  29 2.    COPYRIGHT LICENSE
  30
  31 Redistribution and use in source and binary forms, with or without modification, are permitted without
  32 payment of copyright license fees provided that you satisfy the following conditions:
  33
  34 You must retain the complete text of this software license in redistributions of the FDK AAC Codec or
  35 your modifications thereto in source code form.
  36
  37 You must retain the complete text of this software license in the documentation and/or other materials
  38 provided with redistributions of the FDK AAC Codec or your modifications thereto in binary form.
  39 You must make available free of charge copies of the complete source code of the FDK AAC Codec and your
  40 modifications thereto to recipients of copies in binary form.
  41
  42 The name of Fraunhofer may not be used to endorse or promote products derived from this library without
  43 prior written permission.
  44
  45 You may not charge copyright license fees for anyone to use, copy or distribute the FDK AAC Codec
  46 software or your modifications thereto.
  47
  48 Your modified versions of the FDK AAC Codec must carry prominent notices stating that you changed the software
  49 and the date of any change. For modified versions of the FDK AAC Codec, the term
  50 "Fraunhofer FDK AAC Codec Library for Android" must be replaced by the term
  51 "Third-Party Modified Version of the Fraunhofer FDK AAC Codec Library for Android."
  52
  53 3.    NO PATENT LICENSE
  54
  55 NO EXPRESS OR IMPLIED LICENSES TO ANY PATENT CLAIMS, including without limitation the patents of Fraunhofer,
  56 ARE GRANTED BY THIS SOFTWARE LICENSE. Fraunhofer provides no warranty of patent non-infringement with
  57 respect to this software.
  58
  59 You may use this FDK AAC Codec software or modifications thereto only for purposes that are authorized
  60 by appropriate patent licenses.
  61
  62 4.    DISCLAIMER
  63
  64 This FDK AAC Codec software is provided by Fraunhofer on behalf of the copyright holders and contributors
  65 "AS IS" and WITHOUT ANY EXPRESS OR IMPLIED WARRANTIES, including but not limited to the implied warranties
  66 of merchantability and fitness for a particular purpose. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR
  67 CONTRIBUTORS BE LIABLE for any direct, indirect, incidental, special, exemplary, or consequential damages,
  68 including but not limited to procurement of substitute goods or services; loss of use, data, or profits,
  69 or business interruption, however caused and on any theory of liability, whether in contract, strict
  70 liability, or tort (including negligence), arising in any way out of the use of this software, even if
  71 advised of the possibility of such damage.
  72
  73 5.    CONTACT INFORMATION
  74
  75 Fraunhofer Institute for Integrated Circuits IIS
  76 Attention: Audio and Multimedia Departments - FDK AAC LL
  77 Am Wolfsmantel 33
  78 91058 Erlangen, Germany
  79
  80 www.iis.fraunhofer.de/amm
  81 amm-info@iis.fraunhofer.de
  82 ----------------------------------------------------------------------------------------------------------- */
  83
  84 /*!
  85   \file
  86   \brief  FDK Fixed Point Arithmetic Library Interface
  87 */
  88
  89 #ifndef __TRANSCENDENT_H
  90 #define __TRANSCENDENT_H
  91
  92 #include "sbrdecoder.h"
  93 #include "sbr_rom.h"
  94
  95 /************************************************************************/
  96 /*!
  97   \brief   Get number of octaves between frequencies a and b
  98
  99   The Result is scaled with 1/8.
 100   The valid range for a and b is 1 to LOG_DUALIS_TABLE_SIZE.
 101
 102   \return   ld(a/b) / 8
 103 */
 104 /************************************************************************/
 105 static inline FIXP_SGL FDK_getNumOctavesDiv8(INT a, /*!< lower band */
 106                                              INT b) /*!< upper band */
 107 {
 108   return ( (SHORT)((LONG)(CalcLdInt(b) - CalcLdInt(a))>>(FRACT_BITS-3)) );
 109 }
 110
 111
 112 /************************************************************************/
 113 /*!
 114   \brief   Add two values given by mantissa and exponent.
 115
 116   Mantissas are in fract format with values between 0 and 1. <br>
 117   The base for exponents is 2.  Example:  \f$  a = a\_m * 2^{a\_e}  \f$<br>
 118 */
 119 /************************************************************************/
 120 inline void FDK_add_MantExp(FIXP_SGL a_m, /*!< Mantissa of 1st operand a */
 121                      SCHAR     a_e,       /*!< Exponent of 1st operand a */
 122                      FIXP_SGL  b_m,       /*!< Mantissa of 2nd operand b */
 123                      SCHAR     b_e,       /*!< Exponent of 2nd operand b */
 124                      FIXP_SGL *ptrSum_m,  /*!< Mantissa of result */
 125                      SCHAR    *ptrSum_e)  /*!< Exponent of result */
 126 {
 127   FIXP_DBL accu;
 128   int   shift;
 129   int   shiftAbs;
 130
 131   FIXP_DBL shiftedMantissa;
 132   FIXP_DBL otherMantissa;
 133
 134   /* Equalize exponents of the summands.
 135      For the smaller summand, the exponent is adapted and
 136      for compensation, the mantissa is shifted right. */
 137
 138   shift = (int)(a_e - b_e);
 139
 140   shiftAbs = (shift>0)? shift : -shift;
 141   shiftAbs = (shiftAbs < DFRACT_BITS-1)? shiftAbs : DFRACT_BITS-1;
 142   shiftedMantissa = (shift>0)? (FX_SGL2FX_DBL(b_m) >> shiftAbs) : (FX_SGL2FX_DBL(a_m) >> shiftAbs);
 143   otherMantissa = (shift>0)? FX_SGL2FX_DBL(a_m) : FX_SGL2FX_DBL(b_m);
 144   *ptrSum_e = (shift>0)? a_e : b_e;
 145
 146   accu = (shiftedMantissa >> 1) + (otherMantissa >> 1);
 147   /* shift by 1 bit to avoid overflow */
 148
 149   if ( (accu >= (FL2FXCONST_DBL(0.5f) - (FIXP_DBL)1)) || (accu <= FL2FXCONST_DBL(-0.5f)) )
 150     *ptrSum_e += 1;
 151   else
 152     accu = (shiftedMantissa + otherMantissa);
 153
 154   *ptrSum_m = FX_DBL2FX_SGL(accu);
 155
 156 }
 157
 158 inline void FDK_add_MantExp(FIXP_DBL a,   /*!< Mantissa of 1st operand a */
 159                      SCHAR     a_e,       /*!< Exponent of 1st operand a */
 160                      FIXP_DBL  b,         /*!< Mantissa of 2nd operand b */
 161                      SCHAR     b_e,       /*!< Exponent of 2nd operand b */
 162                      FIXP_DBL *ptrSum,    /*!< Mantissa of result */
 163                      SCHAR    *ptrSum_e)  /*!< Exponent of result */
 164 {
 165   FIXP_DBL accu;
 166   int   shift;
 167   int   shiftAbs;
 168
 169   FIXP_DBL shiftedMantissa;
 170   FIXP_DBL otherMantissa;
 171
 172   /* Equalize exponents of the summands.
 173      For the smaller summand, the exponent is adapted and
 174      for compensation, the mantissa is shifted right. */
 175
 176   shift = (int)(a_e - b_e);
 177
 178   shiftAbs = (shift>0)? shift : -shift;
 179   shiftAbs = (shiftAbs < DFRACT_BITS-1)? shiftAbs : DFRACT_BITS-1;
 180   shiftedMantissa = (shift>0)? (b >> shiftAbs) : (a >> shiftAbs);
 181   otherMantissa = (shift>0)? a : b;
 182   *ptrSum_e = (shift>0)? a_e : b_e;
 183
 184   accu = (shiftedMantissa >> 1) + (otherMantissa >> 1);
 185   /* shift by 1 bit to avoid overflow */
 186
 187   if ( (accu >= (FL2FXCONST_DBL(0.5f) - (FIXP_DBL)1)) || (accu <= FL2FXCONST_DBL(-0.5f)) )
 188     *ptrSum_e += 1;
 189   else
 190     accu = (shiftedMantissa + otherMantissa);
 191
 192   *ptrSum = accu;
 193
 194 }
 195
 196 /************************************************************************/
 197 /*!
 198   \brief   Divide two values given by mantissa and exponent.
 199
 200   Mantissas are in fract format with values between 0 and 1. <br>
 201   The base for exponents is 2.  Example:  \f$  a = a\_m * 2^{a\_e}  \f$<br>
 202
 203   For performance reasons, the division is based on a table lookup
 204   which limits accuracy.
 205 */
 206 /************************************************************************/
 207 static inline void FDK_divide_MantExp(FIXP_SGL a_m,           /*!< Mantissa of dividend a */
 208                                       SCHAR     a_e,          /*!< Exponent of dividend a */
 209                                       FIXP_SGL  b_m,          /*!< Mantissa of divisor b */
 210                                       SCHAR     b_e,          /*!< Exponent of divisor b */
 211                                       FIXP_SGL *ptrResult_m,  /*!< Mantissa of quotient a/b */
 212                                       SCHAR    *ptrResult_e)  /*!< Exponent of quotient a/b */
 213
 214 {
 215   int preShift, postShift, index, shift;
 216   FIXP_DBL ratio_m;
 217   FIXP_SGL  bInv_m = FL2FXCONST_SGL(0.0f);
 218
 219   preShift = CntLeadingZeros(FX_SGL2FX_DBL(b_m));
 220
 221   /*
 222     Shift b into the range from 0..INV_TABLE_SIZE-1,
 223
 224     E.g. 10 bits must be skipped for INV_TABLE_BITS 8:
 225     - leave 8 bits as index for table
 226     - skip sign bit,
 227     - skip first bit of mantissa, because this is always the same (>0.5)
 228
 229     We are dealing with energies, so we need not care
 230     about negative numbers
 231   */
 232
 233   /*
 234     The first interval has half width so the lowest bit of the index is
 235     needed for a doubled resolution.
 236   */
 237   shift = (FRACT_BITS - 2 - INV_TABLE_BITS - preShift);
 238
 239   index = (shift<0)? (LONG)b_m << (-shift) : (LONG)b_m >> shift;
 240
 241
 242   /* The index has INV_TABLE_BITS +1 valid bits here. Clear the other bits. */
 243   index &= (1 << (INV_TABLE_BITS+1)) - 1;
 244
 245     /* Remove offset of half an interval */
 246   index--;
 247
 248     /* Now the lowest bit is shifted out */
 249   index = index >> 1;
 250
 251     /* Fetch inversed mantissa from table: */
 252   bInv_m = (index<0)? bInv_m : FDK_sbrDecoder_invTable[index];
 253
 254     /* Multiply a with the inverse of b: */
 255   ratio_m = (index<0)? FX_SGL2FX_DBL(a_m >> 1) : fMultDiv2(bInv_m,a_m);
 256
 257   postShift = CntLeadingZeros(ratio_m)-1;
 258
 259   *ptrResult_m = FX_DBL2FX_SGL(ratio_m << postShift);
 260   *ptrResult_e = a_e - b_e + 1 + preShift - postShift;
 261 }
 262
 263 static inline void FDK_divide_MantExp(FIXP_DBL a_m,           /*!< Mantissa of dividend a */
 264                                       SCHAR     a_e,          /*!< Exponent of dividend a */
 265                                       FIXP_DBL  b_m,          /*!< Mantissa of divisor b */
 266                                       SCHAR     b_e,          /*!< Exponent of divisor b */
 267                                       FIXP_DBL *ptrResult_m,  /*!< Mantissa of quotient a/b */
 268                                       SCHAR    *ptrResult_e)  /*!< Exponent of quotient a/b */
 269
 270 {
 271   int preShift, postShift, index, shift;
 272   FIXP_DBL ratio_m;
 273   FIXP_SGL  bInv_m = FL2FXCONST_SGL(0.0f);
 274
 275   preShift = CntLeadingZeros(b_m);
 276
 277   /*
 278     Shift b into the range from 0..INV_TABLE_SIZE-1,
 279
 280     E.g. 10 bits must be skipped for INV_TABLE_BITS 8:
 281     - leave 8 bits as index for table
 282     - skip sign bit,
 283     - skip first bit of mantissa, because this is always the same (>0.5)
 284
 285     We are dealing with energies, so we need not care
 286     about negative numbers
 287   */
 288
 289   /*
 290     The first interval has half width so the lowest bit of the index is
 291     needed for a doubled resolution.
 292   */
 293   shift = (DFRACT_BITS - 2 - INV_TABLE_BITS - preShift);
 294
 295   index = (shift<0)? (LONG)b_m << (-shift) : (LONG)b_m >> shift;
 296
 297
 298   /* The index has INV_TABLE_BITS +1 valid bits here. Clear the other bits. */
 299   index &= (1 << (INV_TABLE_BITS+1)) - 1;
 300
 301     /* Remove offset of half an interval */
 302   index--;
 303
 304     /* Now the lowest bit is shifted out */
 305   index = index >> 1;
 306
 307     /* Fetch inversed mantissa from table: */
 308   bInv_m = (index<0)? bInv_m : FDK_sbrDecoder_invTable[index];
 309
 310     /* Multiply a with the inverse of b: */
 311   ratio_m = (index<0)? (a_m >> 1) : fMultDiv2(bInv_m,a_m);
 312
 313   postShift = CntLeadingZeros(ratio_m)-1;
 314
 315   *ptrResult_m = ratio_m << postShift;
 316   *ptrResult_e = a_e - b_e + 1 + preShift - postShift;
 317 }
 318
 319 /*!
 320   \brief   Calculate the squareroot of a number given by mantissa and exponent
 321
 322   Mantissa is in fract format with values between 0 and 1. <br>
 323   The base for the exponent is 2.  Example:  \f$  a = a\_m * 2^{a\_e}  \f$<br>
 324   The operand is addressed via pointers and will be overwritten with the result.
 325
 326   For performance reasons, the square root is based on a table lookup
 327   which limits accuracy.
 328 */
 329 static inline void FDK_sqrt_MantExp(FIXP_DBL *mantissa,    /*!< Pointer to mantissa */
 330                                     SCHAR    *exponent,
 331                                     const SCHAR *destScale)
 332 {
 333   FIXP_DBL input_m = *mantissa;
 334   int   input_e = (int) *exponent;
 335   FIXP_DBL result = FL2FXCONST_DBL(0.0f);
 336   int    result_e = -FRACT_BITS;
 337
 338   /* Call lookup square root, which does internally normalization. */
 339   result   = sqrtFixp_lookup(input_m, &input_e);
 340   result_e = input_e;
 341
 342   /* Write result */
 343   if (exponent==destScale) {
 344     *mantissa = result;
 345     *exponent = result_e;
 346   } else {
 347     int shift = result_e - *destScale;
 348     *mantissa = (shift>=0) ? result << (INT)fixMin(DFRACT_BITS-1,shift)
 349                            : result >> (INT)fixMin(DFRACT_BITS-1,-shift);
 350     *exponent = *destScale;
 351   }
 352 }
 353
 354
 355 #endif