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fastmath: Remove non builtin dependencies to math library

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This commit is contained in:
Antoine Soulier
2024-01-26 15:45:09 -08:00
committed by Antoine SOULIER
parent 2e655459eb
commit d7a739849a
3 changed files with 55 additions and 10 deletions
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47
src/fastmath.h
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@@ -23,6 +23,51 @@
#include <math.h>
/**
* IEEE 754 Floating point representation
*/
#define LC3_IEEE754_SIGN_SHL (31)
#define LC3_IEEE754_SIGN_MASK (1 << LC3_IEEE754_SIGN_SHL)
#define LC3_IEEE754_EXP_SHL (23)
#define LC3_IEEE754_EXP_MASK (0xff << LC3_IEEE754_EXP_SHL)
#define LC3_IEEE754_EXP_BIAS (127)
/**
* Fast multiply floating-point number by integral power of 2
* x Operand, finite number
* exp Exponent such that 2^x is finite
* return 2^exp
*/
static inline float lc3_ldexpf(float _x, int exp) {
union { float f; uint32_t u; } x = { .f = _x };
if (x.u & LC3_IEEE754_EXP_MASK)
x.u += exp << LC3_IEEE754_EXP_SHL;
return x.f;
}
/**
* Fast convert floating-point number to fractional and integral components
* x Operand, finite number
* exp Return the exponent part
* return The normalized fraction in [0.5:1[
*/
static inline float lc3_frexpf(float _x, int *exp) {
union { float f; uint32_t u; } x = { .f = _x };
int e = (x.u & LC3_IEEE754_EXP_MASK) >> LC3_IEEE754_EXP_SHL;
*exp = e - (LC3_IEEE754_EXP_BIAS - 1);
x.u = (x.u & ~LC3_IEEE754_EXP_MASK) |
((LC3_IEEE754_EXP_BIAS - 1) << LC3_IEEE754_EXP_SHL);
return x.f;
}
/**
* Fast 2^n approximation
* x Operand, range -8 to 8
@@ -69,7 +114,7 @@ static inline float lc3_log2f(float x)
static const float c[] = {
-1.29479677, 5.11769018, -8.42295281, 8.10557963, -3.50567360 };
x = frexpf(x, &e);
x = lc3_frexpf(x, &e);
y = ( c[0]) * x;
y = (y + c[1]) * x;

16
src/lc3.c
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@@ -222,7 +222,7 @@ static void load_s24(
for (int i = 0; i < ns; i++, pcm += stride) {
xt[i] = *pcm >> 8;
xs[i] = ldexpf(*pcm, -8);
xs[i] = lc3_ldexpf(*pcm, -8);
}
}
@@ -249,7 +249,7 @@ static void load_s24_3le(
((uint32_t)pcm[2] << 24) ;
xt[i] = in >> 16;
xs[i] = ldexpf(in, -16);
xs[i] = lc3_ldexpf(in, -16);
}
}
@@ -271,7 +271,7 @@ static void load_float(
int ns = lc3_ns(dt, sr);
for (int i = 0; i < ns; i++, pcm += stride) {
xs[i] = ldexpf(*pcm, 15);
xs[i] = lc3_ldexpf(*pcm, 15);
xt[i] = LC3_SAT16((int32_t)xs[i]);
}
}
@@ -500,8 +500,8 @@ static void store_s24(
int ns = lc3_ns(dt, sr);
for ( ; ns > 0; ns--, xs++, pcm += stride) {
int32_t s = *xs >= 0 ? (int32_t)(ldexpf(*xs, 8) + 0.5f)
: (int32_t)(ldexpf(*xs, 8) - 0.5f);
int32_t s = *xs >= 0 ? (int32_t)(lc3_ldexpf(*xs, 8) + 0.5f)
: (int32_t)(lc3_ldexpf(*xs, 8) - 0.5f);
*pcm = LC3_SAT24(s);
}
}
@@ -523,8 +523,8 @@ static void store_s24_3le(
int ns = lc3_ns(dt, sr);
for ( ; ns > 0; ns--, xs++, pcm += 3*stride) {
int32_t s = *xs >= 0 ? (int32_t)(ldexpf(*xs, 8) + 0.5f)
: (int32_t)(ldexpf(*xs, 8) - 0.5f);
int32_t s = *xs >= 0 ? (int32_t)(lc3_ldexpf(*xs, 8) + 0.5f)
: (int32_t)(lc3_ldexpf(*xs, 8) - 0.5f);
s = LC3_SAT24(s);
pcm[0] = (s >> 0) & 0xff;
@@ -550,7 +550,7 @@ static void store_float(
int ns = lc3_ns(dt, sr);
for ( ; ns > 0; ns--, xs++, pcm += stride) {
float s = ldexpf(*xs, -15);
float s = lc3_ldexpf(*xs, -15);
*pcm = fminf(fmaxf(s, -1.f), 1.f);
}
}

2
src/spec.c
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@@ -135,7 +135,7 @@ LC3_HOT static int estimate_gain(
float x_max = sqrtf(x2_max);
float nf = lc3_hr(sr) ?
ldexpf(x_max, -reg_bits) * lc3_exp2f(-low_bits) : 0;
lc3_ldexpf(x_max, -reg_bits) * lc3_exp2f(-low_bits) : 0;
for (int i = 0; i < n4; i++)
e[i].q16 = lc3_db_q16(fmaxf(e[i].f + nf, 1e-10f));