fixpoint_math.h - Android社区 - https://www.androidos.net.cn/

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Attention: Audio and Multimedia Departments - FDK AAC LL
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----------------------------------------------------------------------------------------------------------- */

/***************************  Fraunhofer IIS FDK Tools  **********************

Author(s):   M. Gayer
   Description: Fixed point specific mathematical functions

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

#ifndef __fixpoint_math_H
#define __fixpoint_math_H

#include "common_fix.h"

#if !defined(FUNCTION_fIsLessThan)
/**
 * \brief Compares two fixpoint values incl. scaling.
 * \param a_m mantissa of the first input value.
 * \param a_e exponent of the first input value.
 * \param b_m mantissa of the second input value.
 * \param b_e exponent of the second input value.
 * \return non-zero if (a_m*2^a_e) < (b_m*2^b_e), 0 otherwise
 */
FDK_INLINE INT fIsLessThan(FIXP_DBL a_m, INT a_e, FIXP_DBL b_m, INT b_e)
{
  if (a_e > b_e) {
    return (b_m >> fMin(a_e-b_e, DFRACT_BITS-1) > a_m);
  } else {
    return (a_m >> fMin(b_e-a_e, DFRACT_BITS-1) < b_m);
  }
}

FDK_INLINE INT fIsLessThan(FIXP_SGL a_m, INT a_e, FIXP_SGL b_m, INT b_e)
{
  if (a_e > b_e) {
    return (b_m >> fMin(a_e-b_e, FRACT_BITS-1) > a_m);
  } else {
    return (a_m >> fMin(b_e-a_e, FRACT_BITS-1) < b_m);
  }
}
#endif

#define LD_DATA_SCALING (64.0f)
#define LD_DATA_SHIFT   6   /* pow(2, LD_DATA_SHIFT) = LD_DATA_SCALING */

/**
 * \brief deprecated. Use fLog2() instead.
 */
FIXP_DBL CalcLdData(FIXP_DBL op);

void LdDataVector(FIXP_DBL *srcVector, FIXP_DBL *destVector, INT number);

FIXP_DBL CalcInvLdData(FIXP_DBL op);

void     InitLdInt();
FIXP_DBL CalcLdInt(INT i);

extern const USHORT sqrt_tab[49];

inline FIXP_DBL sqrtFixp_lookup(FIXP_DBL x)
{
  UINT y = (INT)x;
  UCHAR is_zero=(y==0);
  INT zeros=fixnormz_D(y) & 0x1e;
  y<<=zeros;
  UINT idx=(y>>26)-16;
  USHORT frac=(y>>10)&0xffff;
  USHORT nfrac=0xffff^frac;
  UINT t=nfrac*sqrt_tab[idx]+frac*sqrt_tab[idx+1];
  t=t>>(zeros>>1);
  return(is_zero ? 0 : t);
}

inline FIXP_DBL sqrtFixp_lookup(FIXP_DBL x, INT *x_e)
{
  UINT y = (INT)x;
  INT e;

if (x == (FIXP_DBL)0) {
    return x;
  }

/* Normalize */
  e=fixnormz_D(y);
  y<<=e;
  e  = *x_e - e + 2;

/* Correct odd exponent. */
  if (e & 1) {
    y >>= 1;
    e ++;
  }
  /* Get square root */
  UINT idx=(y>>26)-16;
  USHORT frac=(y>>10)&0xffff;
  USHORT nfrac=0xffff^frac;
  UINT t=nfrac*sqrt_tab[idx]+frac*sqrt_tab[idx+1];

/* Write back exponent */
  *x_e = e >> 1;
  return (FIXP_DBL)(LONG)(t>>1);
}

FIXP_DBL sqrtFixp(FIXP_DBL op);

void InitInvSqrtTab();

FIXP_DBL invSqrtNorm2(FIXP_DBL op, INT *shift);

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

functionname: invFixp
    description:  delivers 1/(op)

*****************************************************************************/
inline FIXP_DBL invFixp(FIXP_DBL op)
{
    INT tmp_exp ;
    FIXP_DBL tmp_inv = invSqrtNorm2(op, &tmp_exp) ;
    FDK_ASSERT((31-(2*tmp_exp+1))>=0) ;
    return ( fPow2Div2( (FIXP_DBL)tmp_inv ) >> (31-(2*tmp_exp+1)) ) ;
}

#if defined(__mips__) && (__GNUC__==2)

#define FUNCTION_schur_div
inline FIXP_DBL schur_div(FIXP_DBL num,FIXP_DBL denum, INT count)
{
  INT result, tmp ;
   __asm__ ("srl %1, %2, 15\n"
            "div %3, %1\n" : "=lo" (result)
                           : "%d" (tmp), "d" (denum) ,  "d" (num)
                           : "hi" ) ;
  return result<<16 ;
}

/*###########################################################################################*/
#elif defined(__mips__) && (__GNUC__==3)

#define FUNCTION_schur_div
inline FIXP_DBL schur_div(FIXP_DBL num,FIXP_DBL denum, INT count)
{
  INT result, tmp;

__asm__ ("srl  %[tmp], %[denum], 15\n"
            "div %[result], %[num], %[tmp]\n"
            : [tmp] "+r" (tmp), [result]"=r"(result)
            : [denum]"r"(denum), [num]"r"(num)
            : "hi", "lo");
  return result << (DFRACT_BITS-16);
}

/*###########################################################################################*/
#elif defined(SIMULATE_MIPS_DIV)

#define FUNCTION_schur_div
inline FIXP_DBL schur_div(FIXP_DBL num, FIXP_DBL denum, INT count)
{
    FDK_ASSERT (count<=DFRACT_BITS-1);
    FDK_ASSERT (num>=(FIXP_DBL)0);
    FDK_ASSERT (denum>(FIXP_DBL)0);
    FDK_ASSERT (num <= denum);

INT tmp = denum >> (count-1);
    INT result = 0;

while (num > tmp)
    {
        num -= tmp;
        result++;
    }

return result << (DFRACT_BITS-count);
}

/*###########################################################################################*/
#endif /* target architecture selector */

#if !defined(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
 */
FIXP_DBL schur_div(FIXP_DBL num,FIXP_DBL denum, INT count);
#endif

FIXP_DBL mul_dbl_sgl_rnd (const FIXP_DBL op1,
                          const FIXP_SGL op2);

/**
 * \brief multiply two values with normalization, thus max precision.
 * Author: Robert Weidner
 *
 * \param f1 first factor
 * \param f2 secod factor
 * \param result_e pointer to an INT where the exponent of the result is stored into
 * \return mantissa of the product f1*f2
 */
FIXP_DBL fMultNorm(
        FIXP_DBL f1,
        FIXP_DBL f2,
        INT *result_e
        );

inline FIXP_DBL fMultNorm(FIXP_DBL f1, FIXP_DBL f2)
{
  FIXP_DBL m;
  INT e;

m = fMultNorm(f1, f2, &e);

m = scaleValueSaturate(m, e);

return m;
}

/**
 * \brief Divide 2 FIXP_DBL values with normalization of input values.
 * \param num numerator
 * \param denum denomintator
 * \return num/denum with exponent = 0
 */
FIXP_DBL fDivNorm(FIXP_DBL num, FIXP_DBL denom, INT *result_e);

/**
 * \brief Divide 2 FIXP_DBL values with normalization of input values.
 * \param num numerator
 * \param denum denomintator
 * \param result_e pointer to an INT where the exponent of the result is stored into
 * \return num/denum with exponent = *result_e
 */
FIXP_DBL fDivNorm(FIXP_DBL num, FIXP_DBL denom);

/**
 * \brief Calculate log(argument)/log(2) (logarithm with base 2). deprecated. Use fLog2() instead.
 * \param arg mantissa of the argument
 * \param arg_e exponent of the argument
 * \param result_e pointer to an INT to store the exponent of the result
 * \return the mantissa of the result.
 * \param
 */
FIXP_DBL CalcLog2(FIXP_DBL arg, INT arg_e, INT *result_e);

/**
 * \brief return 2 ^ (exp * 2^exp_e)
 * \param exp_m mantissa of the exponent to 2.0f
 * \param exp_e exponent of the exponent to 2.0f
 * \param result_e pointer to a INT where the exponent of the result will be stored into
 * \return mantissa of the result
 */
FIXP_DBL f2Pow(const FIXP_DBL exp_m, const INT exp_e, INT *result_e);

/**
 * \brief return 2 ^ (exp_m * 2^exp_e). This version returns only the mantissa with implicit exponent of zero.
 * \param exp_m mantissa of the exponent to 2.0f
 * \param exp_e exponent of the exponent to 2.0f
 * \return mantissa of the result
 */
FIXP_DBL f2Pow(const FIXP_DBL exp_m, const INT exp_e);

/**
 * \brief return x ^ (exp * 2^exp_e), where log2(x) = baseLd_m * 2^(baseLd_e). This saves
 *        the need to compute log2() of constant values (when x is a constant).
 * \param ldx_m mantissa of log2() of x.
 * \param ldx_e exponent of log2() of x.
 * \param exp_m mantissa of the exponent to 2.0f
 * \param exp_e exponent of the exponent to 2.0f
 * \param result_e pointer to a INT where the exponent of the result will be stored into
 * \return mantissa of the result
 */
FIXP_DBL fLdPow(
        FIXP_DBL baseLd_m,
        INT baseLd_e,
        FIXP_DBL exp_m, INT exp_e,
        INT *result_e
        );

/**
 * \brief return x ^ (exp * 2^exp_e), where log2(x) = baseLd_m * 2^(baseLd_e). This saves
 *        the need to compute log2() of constant values (when x is a constant). This version
 *        does not return an exponent, which is implicitly 0.
 * \param ldx_m mantissa of log2() of x.
 * \param ldx_e exponent of log2() of x.
 * \param exp_m mantissa of the exponent to 2.0f
 * \param exp_e exponent of the exponent to 2.0f
 * \return mantissa of the result
 */
FIXP_DBL fLdPow(
        FIXP_DBL baseLd_m, INT baseLd_e,
        FIXP_DBL exp_m, INT exp_e
        );

/**
 * \brief return (base * 2^base_e) ^ (exp * 2^exp_e). Use fLdPow() instead whenever possible.
 * \param base_m mantissa of the base.
 * \param base_e exponent of the base.
 * \param exp_m mantissa of power to be calculated of the base.
 * \param exp_e exponent of power to be calculated of the base.
 * \param result_e pointer to a INT where the exponent of the result will be stored into.
 * \return mantissa of the result.
 */
FIXP_DBL fPow(FIXP_DBL base_m, INT base_e, FIXP_DBL exp_m, INT exp_e, INT *result_e);

/**
 * \brief return (base * 2^base_e) ^ N
 * \param base mantissa of the base
 * \param base_e exponent of the base
 * \param power to be calculated of the base
 * \param result_e pointer to a INT where the exponent of the result will be stored into
 * \return mantissa of the result
 */
FIXP_DBL fPowInt(FIXP_DBL base_m, INT base_e, INT N, INT *result_e);

/**
 * \brief calculate logarithm of base 2 of x_m * 2^(x_e)
 * \param x_m mantissa of the input value.
 * \param x_e exponent of the input value.
 * \param pointer to an INT where the exponent of the result is returned into.
 * \return mantissa of the result.
 */
FIXP_DBL fLog2(FIXP_DBL x_m, INT x_e, INT *result_e);

/**
 * \brief calculate logarithm of base 2 of x_m * 2^(x_e)
 * \param x_m mantissa of the input value.
 * \param x_e exponent of the input value.
 * \return mantissa of the result with implicit exponent of LD_DATA_SHIFT.
 */
FIXP_DBL fLog2(FIXP_DBL x_m, INT x_e);

/**
 * \brief Add with saturation of the result.
 * \param a first summand
 * \param b second summand
 * \return saturated sum of a and b.
 */
inline FIXP_SGL fAddSaturate(const FIXP_SGL a, const FIXP_SGL b)
{
  LONG sum;

sum = (LONG)(SHORT)a + (LONG)(SHORT)b;
  sum = fMax(fMin((INT)sum, (INT)MAXVAL_SGL), (INT)MINVAL_SGL);
  return (FIXP_SGL)(SHORT)sum;
}

/**
 * \brief Add with saturation of the result.
 * \param a first summand
 * \param b second summand
 * \return saturated sum of a and b.
 */
inline FIXP_DBL fAddSaturate(const FIXP_DBL a, const FIXP_DBL b)
{
  LONG sum;

sum = (LONG)(a>>1) + (LONG)(b>>1);
  sum = fMax(fMin((INT)sum, (INT)(MAXVAL_DBL>>1)), (INT)(MINVAL_DBL>>1));
  return (FIXP_DBL)(LONG)(sum<<1);
}

//#define TEST_ROUNDING

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

array for 1/n, n=1..80

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

extern const FIXP_DBL invCount[80];

LNK_SECTION_INITCODE
  inline void InitInvInt(void) {}

/**
 * \brief Calculate the value of 1/i where i is a integer value. It supports
 *        input values from 1 upto 80.
 * \param intValue Integer input value.
 * \param FIXP_DBL representation of 1/intValue
 */
inline FIXP_DBL GetInvInt(int intValue)
{
  FDK_ASSERT((intValue > 0) && (intValue < 80));
  FDK_ASSERT(intValue<80);
	return invCount[intValue];
}

#endif

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