fdk-aac/libFDK/include/x86/fixpoint_math_x86.h

/* -----------------------------------------------------------------------------
Software License for The Fraunhofer FDK AAC Codec Library for Android

© Copyright  1995 - 2018 Fraunhofer-Gesellschaft zur Förderung der angewandten
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 1.    INTRODUCTION
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that implements the MPEG Advanced Audio Coding ("AAC") encoding and decoding
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AAC's HE-AAC and HE-AAC v2 versions are regarded as today's most efficient
general perceptual audio codecs. AAC-ELD is considered the best-performing
full-bandwidth communications codec by independent studies and is widely
deployed. AAC has been standardized by ISO and IEC as part of the MPEG
specifications.

Patent licenses for necessary patent claims for the FDK AAC Codec (including
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Attention: Audio and Multimedia Departments - FDK AAC LL
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----------------------------------------------------------------------------- */

/******************* Library for basic calculation routines ********************

   Author(s):   Manuel Jander

   Description: Fixed point specific mathematical functions for x86

*******************************************************************************/

#if !defined(FIXPOINT_MATH_X86_H)
#define FIXPOINT_MATH_X86_H

#define FUNCTION_sqrtFixp

#include <math.h>

#ifdef FUNCTION_sqrtFixp
static inline FIXP_DBL sqrtFixp(const FIXP_DBL op) {
  FIXP_DBL result;
  /* result =
   * (FIXP_DBL)(INT)(sqrt((double)(INT)op)*46340.950011841578559133736114903);
   */
  result = (FIXP_DBL)(INT)(sqrt((float)(INT)op) * 46340.9492f);
  FDK_ASSERT(result >= (FIXP_DBL)0);
  return result;
}
#endif /* FUNCTION_sqrtFixp */

#include <math.h>

#define FUNCTION_invSqrtNorm2
/**
 * \brief calculate 1.0/sqrt(op)
 * \param op_m mantissa of input value.
 * \param result_e pointer to return the exponent of the result
 * \return mantissa of the result
 */
#ifdef FUNCTION_invSqrtNorm2
inline FIXP_DBL invSqrtNorm2(FIXP_DBL op_m, INT *result_e) {
  float result;
  if (op_m == (FIXP_DBL)0) {
    *result_e = 16;
    return ((LONG)0x7fffffff);
  }
  result = (float)(1.0 / sqrt(0.5f * (float)(INT)op_m));
  result = (float)ldexp(frexpf(result, result_e), DFRACT_BITS - 1);
  *result_e += 15;

  FDK_ASSERT(result >= 0);
  return (FIXP_DBL)(INT)result;
}
#endif /* FUNCTION_invSqrtNorm2 */

#define FUNCTION_invFixp
/**
 * \brief calculate 1.0/op
 * \param op mantissa of the input value.
 * \return mantissa of the result with implizit exponent of 31
 */
#ifdef FUNCTION_invFixp
inline FIXP_DBL invFixp(FIXP_DBL op) {
  float result;
  INT result_e;
  if ((op == (FIXP_DBL)0) || (op == (FIXP_DBL)1)) {
    return ((LONG)0x7fffffff);
  }
  result = (float)(1.0 / (float)(INT)op);
  result = frexpf(result, &result_e);
  result = ldexpf(result, 31 + result_e);

  return (FIXP_DBL)(INT)result;
}

/**
 * \brief calculate 1.0/(op_m * 2^op_e)
 * \param op_m mantissa of the input value.
 * \param op_e pointer into were the exponent of the input value is stored, and
 * the result will be stored into.
 * \return mantissa of the result
 */
inline FIXP_DBL invFixp(FIXP_DBL op_m, int *op_e) {
  float result;
  INT result_e;
  if ((op_m == (FIXP_DBL)0x00000000) || (op_m == (FIXP_DBL)0x00000001)) {
    *op_e = 31 - *op_e;
    return ((LONG)0x7fffffff);
  }
  result = (float)(1.0 / (float)(INT)op_m);
  result = ldexpf(frexpf(result, &result_e), DFRACT_BITS - 1);
  *op_e = result_e - *op_e + 31;
  return (FIXP_DBL)(INT)result;
}
#endif /* FUNCTION_invFixp */

#define FUNCTION_schur_div
/**
 * \brief Divide two FIXP_DBL values with given precision.
 * \param num dividend
 * \param denum divisor
 * \param count amount of significant bits of the result (starting to the MSB)
 * \return num/divisor
 */
#ifdef FUNCTION_schur_div
inline FIXP_DBL schur_div(FIXP_DBL num, FIXP_DBL denum, INT count) {
  (void)count;
  /* same asserts than for fallback implementation */
  FDK_ASSERT(num >= (FIXP_DBL)0);
  FDK_ASSERT(denum > (FIXP_DBL)0);
  FDK_ASSERT(num <= denum);

  return (num == denum) ? (FIXP_DBL)MAXVAL_DBL
                        : (FIXP_DBL)(INT)(((INT64)(INT)num << 31) / (INT)denum);
}
#endif /* FUNCTION_schur_div */
#endif /* !defined(FIXPOINT_MATH_X86_H) */