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LibM: Reimplement some functions using FPU

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This commit is contained in:
Egor Ananyin 2020-12-29 13:44:28 +03:00 committed by Andreas Kling
parent f1b596e75e
commit 92c6ae57fc
Notes: sideshowbarker 2024-07-19 00:27:40 +09:00 
Author: https://github.com/Cleverking2003
Commit: https://github.com/SerenityOS/serenity/commit/92c6ae57fce
Pull-request: https://github.com/SerenityOS/serenity/pull/4622
Issue: https://github.com/SerenityOS/serenity/issues/4543
1 changed files with 93 additions and 73 deletions
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166
Libraries/LibM/math.cpp
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@ -102,8 +102,12 @@ float sinf(float angle) NOEXCEPT
double pow(double x, double y) NOEXCEPT
{
// FIXME: Please fix me. I am naive.
if (isnan(y))
return y;
if (y == 0)
return 1;
if (x == 0)
return 0;
if (y == 1)
return x;
int y_as_int = (int)y;
@ -115,40 +119,22 @@ double pow(double x, double y) NOEXCEPT
result = 1.0 / result;
return result;
}
return exp(y * log(x));
return exp2(y * log2(x));
}
float powf(float x, float y) NOEXCEPT
{
// FIXME: Please fix me. I am naive.
if (y == 0)
return 1;
if (y == 1)
return x;
int y_as_int = (int)y;
if (y == (float)y_as_int) {
float result = x;
for (int i = 0; i < fabs(y) - 1; ++i)
result *= x;
if (y < 0)
result = 1.0 / result;
return result;
}
return (float)exp((double)y * log((double)x));
return (float)pow(x, y);
}
double ldexp(double x, int exp) NOEXCEPT
{
// FIXME: Please fix me. I am naive.
double val = pow(2, exp);
return x * val;
return x * exp2(exp);
}
float ldexpf(float x, int exp) NOEXCEPT
{
// FIXME: Please fix me. I am naive.
float val = powf(2, exp);
return x * val;
return x * exp2f(exp);
}
double tanh(double x) NOEXCEPT
@ -212,22 +198,28 @@ double sinh(double x) NOEXCEPT
double log10(double x) NOEXCEPT
{
return log(x) / M_LN10;
double ret = 0.0;
__asm__(
"fldlg2\n"
"fld %%st(1)\n"
"fyl2x\n"
"fstp %%st(1)"
: "=t"(ret)
: "0"(x));
return ret;
}
double log(double x) NOEXCEPT
{
if (x < 0)
return NAN;
if (x == 0)
return -INFINITY;
double y = 1 + 2 * (x - 1) / (x + 1);
double exponentiated = exp(y);
y = y + 2 * (x - exponentiated) / (x + exponentiated);
exponentiated = exp(y);
y = y + 2 * (x - exponentiated) / (x + exponentiated);
exponentiated = exp(y);
return y + 2 * (x - exponentiated) / (x + exponentiated);
double ret = 0.0;
__asm__(
"fldln2\n"
"fld %%st(1)\n"
"fyl2x\n"
"fstp %%st(1)"
: "=t"(ret)
: "0"(x));
return ret;
}
float logf(float x) NOEXCEPT
@ -247,38 +239,19 @@ float fmodf(float index, float period) NOEXCEPT
double exp(double exponent) NOEXCEPT
{
double result = 1;
if (exponent >= 1) {
size_t integer_part = (size_t)exponent;
if (integer_part & 1)
result *= e_to_power<1>();
if (integer_part & 2)
result *= e_to_power<2>();
if (integer_part > 3) {
if (integer_part & 4)
result *= e_to_power<4>();
if (integer_part & 8)
result *= e_to_power<8>();
if (integer_part & 16)
result *= e_to_power<16>();
if (integer_part & 32)
result *= e_to_power<32>();
if (integer_part >= 64)
return INFINITY;
}
exponent -= integer_part;
} else if (exponent < 0)
return 1 / exp(-exponent);
double taylor_series_result = 1 + exponent;
double taylor_series_numerator = exponent * exponent;
taylor_series_result += taylor_series_numerator / factorial<2>();
taylor_series_numerator *= exponent;
taylor_series_result += taylor_series_numerator / factorial<3>();
taylor_series_numerator *= exponent;
taylor_series_result += taylor_series_numerator / factorial<4>();
taylor_series_numerator *= exponent;
taylor_series_result += taylor_series_numerator / factorial<5>();
return result * taylor_series_result;
double res = 0;
__asm__("fldl2e\n"
"fmulp\n"
"fld1\n"
"fld %%st(1)\n"
"fprem\n"
"f2xm1\n"
"faddp\n"
"fscale\n"
"fstp %%st(1)"
: "=t"(res)
: "0"(exponent));
return res;
}
float expf(float exponent) NOEXCEPT
@ -288,12 +261,22 @@ float expf(float exponent) NOEXCEPT
double exp2(double exponent) NOEXCEPT
{
return pow(2.0, exponent);
double res = 0;
__asm__("fld1\n"
"fld %%st(1)\n"
"fprem\n"
"f2xm1\n"
"faddp\n"
"fscale\n"
"fstp %%st(1)"
: "=t"(res)
: "0"(exponent));
return res;
}
float exp2f(float exponent) NOEXCEPT
{
return pow(2.0f, exponent);
return (float)exp2(exponent);
}
double cosh(double x) NOEXCEPT
@ -380,7 +363,15 @@ double fabs(double value) NOEXCEPT
double log2(double x) NOEXCEPT
{
return log(x) / M_LN2;
double ret = 0.0;
__asm__(
"fld1\n"
"fld %%st(1)\n"
"fyl2x\n"
"fstp %%st(1)"
: "=t"(ret)
: "0"(x));
return ret;
}
float log2f(float x) NOEXCEPT
@ -490,16 +481,45 @@ double gamma(double x) NOEXCEPT
double expm1(double x) NOEXCEPT
{
return pow(M_E, x) - 1;
return exp(x) - 1;
}
double cbrt(double x) NOEXCEPT
{
if (x > 0) {
return pow(x, 1.0 / 3.0);
if (isinf(x) || x == 0)
return x;
if (x < 0)
return -cbrt(-x);
double r = x;
double ex = 0;
while (r < 0.125) {
r *= 8;
ex--;
}
while (r > 1.0) {
r *= 0.125;
ex++;
}
return -pow(-x, 1.0 / 3.0);
r = (-0.46946116 * r + 1.072302) * r + 0.3812513;
while (ex < 0) {
r *= 0.5;
ex++;
}
while (ex > 0) {
r *= 2;
ex--;
}
r = (2.0 / 3.0) * r + (1.0 / 3.0) * x / (r * r);
r = (2.0 / 3.0) * r + (1.0 / 3.0) * x / (r * r);
r = (2.0 / 3.0) * r + (1.0 / 3.0) * x / (r * r);
r = (2.0 / 3.0) * r + (1.0 / 3.0) * x / (r * r);
return r;
}
double log1p(double x) NOEXCEPT