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/* Copyright (c) 2013 The Chromium OS Authors. All rights reserved.
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
#ifndef DRC_MATH_H_
#define DRC_MATH_H_
#ifdef __cplusplus
extern "C" {
#endif
#include <stddef.h>
#include <math.h>
#ifndef __BIONIC__
#include <ieee754.h>
#else
union ieee754_float {
float f;
/* Little endian float fields */
struct {
unsigned int mantissa : 23;
unsigned int exponent : 8;
unsigned int negative : 1;
} ieee;
};
#endif
/* Uncomment to use the slow but accurate functions. */
/* #define SLOW_DB_TO_LINEAR */
/* #define SLOW_LINEAR_TO_DB */
/* #define SLOW_WARP_SIN */
/* #define SLOW_KNEE_EXP */
/* #define SLOW_FREXPF */
#define PI_FLOAT 3.141592653589793f
#define PI_OVER_TWO_FLOAT 1.57079632679489661923f
#define TWO_OVER_PI_FLOAT 0.63661977236758134f
#define NEG_TWO_DB 0.7943282347242815f /* -2dB = 10^(-2/20) */
#ifndef max
#define max(a, b) \
({ \
__typeof__(a) _a = (a); \
__typeof__(b) _b = (b); \
_a > _b ? _a : _b; \
})
#endif
#ifndef min
#define min(a, b) \
({ \
__typeof__(a) _a = (a); \
__typeof__(b) _b = (b); \
_a < _b ? _a : _b; \
})
#endif
#ifndef M_PI
#define M_PI 3.14159265358979323846
#endif
#define PURE __attribute__((pure))
static inline float decibels_to_linear(float decibels) PURE;
static inline float linear_to_decibels(float linear) PURE;
static inline float warp_sinf(float x) PURE;
static inline float warp_asinf(float x) PURE;
static inline float knee_expf(float input) PURE;
extern float db_to_linear[201]; /* from -100dB to 100dB */
void drc_math_init();
/* Rounds the input number to the nearest integer */
#if defined(__arm__)
static inline float round_int(float x)
{
return x < 0 ? (int)(x - 0.5f) : (int)(x + 0.5f);
}
#else
#define round_int rintf /* Uses frintx for arm64 and roundss for SSE4.1 */
#endif
static inline float decibels_to_linear(float decibels)
{
#ifdef SLOW_DB_TO_LINEAR
/* 10^(x/20) = e^(x * log(10^(1/20))) */
return expf(0.1151292546497022f * decibels);
#else
float x;
float fi;
int i;
fi = round_int(decibels);
x = decibels - fi;
i = (int)fi;
i = max(min(i, 100), -100);
/* Coefficients obtained from:
* fpminimax(10^(x/20), [|1,2,3|], [|SG...|], [-0.5;0.5], 1, absolute);
* max error ~= 7.897e-8
*/
const float A3 = 2.54408805631101131439208984375e-4f;
const float A2 = 6.628888659179210662841796875e-3f;
const float A1 = 0.11512924730777740478515625f;
const float A0 = 1.0f;
float x2 = x * x;
return ((A3 * x + A2) * x2 + (A1 * x + A0)) * db_to_linear[i + 100];
#endif
}
static inline float frexpf_fast(float x, int *e)
{
#ifdef SLOW_FREXPF
return frexpf(x, e);
#else
union ieee754_float u;
u.f = x;
int exp = u.ieee.exponent;
if (exp == 0xff)
return NAN;
*e = exp - 126;
u.ieee.exponent = 126;
return u.f;
#endif
}
static inline float linear_to_decibels(float linear)
{
/* For negative or zero, just return a very small dB value. */
if (linear <= 0)
return -1000;
#ifdef SLOW_LINEAR_TO_DB
/* 20 * log10(x) = 20 / log(10) * log(x) */
return 8.6858896380650366f * logf(linear);
#else
int e = 0;
float x = frexpf_fast(linear, &e);
float exp = e;
if (x > 0.707106781186548f) {
x *= 0.707106781186548f;
exp += 0.5f;
}
/* Coefficients obtained from:
* fpminimax(log10(x), 5, [|SG...|], [1/2;sqrt(2)/2], absolute);
* max err ~= 6.088e-8
*/
const float A5 = 1.131880283355712890625f;
const float A4 = -4.258677959442138671875f;
const float A3 = 6.81631565093994140625f;
const float A2 = -6.1185703277587890625f;
const float A1 = 3.6505267620086669921875f;
const float A0 = -1.217894077301025390625f;
float x2 = x * x;
float x4 = x2 * x2;
return ((A5 * x + A4) * x4 + (A3 * x + A2) * x2 + (A1 * x + A0)) *
20.0f +
exp * 6.0205999132796239f;
#endif
}
static inline float warp_sinf(float x)
{
#ifdef SLOW_WARP_SIN
return sinf(PI_OVER_TWO_FLOAT * x);
#else
/* Coefficients obtained from:
* fpminimax(sin(x*pi/2), [|1,3,5,7|], [|SG...|], [-1e-30;1], absolute)
* max err ~= 5.901e-7
*/
const float A7 = -4.3330336920917034149169921875e-3f;
const float A5 = 7.9434238374233245849609375e-2f;
const float A3 = -0.645892798900604248046875f;
const float A1 = 1.5707910060882568359375f;
float x2 = x * x;
float x4 = x2 * x2;
return x * ((A7 * x2 + A5) * x4 + (A3 * x2 + A1));
#endif
}
static inline float warp_asinf(float x)
{
return asinf(x) * TWO_OVER_PI_FLOAT;
}
static inline float knee_expf(float input)
{
#ifdef SLOW_KNEE_EXP
return expf(input);
#else
/* exp(x) = decibels_to_linear(20*log10(e)*x) */
return decibels_to_linear(8.685889638065044f * input);
#endif
}
/* Returns 1 for nan or inf, 0 otherwise. This is faster than the alternative
* return x != 0 && !isnormal(x);
*/
static inline int isbadf(float x)
{
union ieee754_float u;
u.f = x;
return u.ieee.exponent == 0xff;
}
#ifdef __cplusplus
} /* extern "C" */
#endif
#endif /* DRC_MATH_H_ */
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