mirror of
https://github.com/reactos/reactos.git
synced 2024-08-28 14:18:41 +00:00
139 lines
4.1 KiB
C
139 lines
4.1 KiB
C
|
|
/*******************************************************************************
|
|
MIT License
|
|
-----------
|
|
|
|
Copyright (c) 2002-2019 Advanced Micro Devices, Inc.
|
|
|
|
Permission is hereby granted, free of charge, to any person obtaining a copy
|
|
of this Software and associated documentaon files (the "Software"), to deal
|
|
in the Software without restriction, including without limitation the rights
|
|
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
|
|
copies of the Software, and to permit persons to whom the Software is
|
|
furnished to do so, subject to the following conditions:
|
|
|
|
The above copyright notice and this permission notice shall be included in
|
|
all copies or substantial portions of the Software.
|
|
|
|
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
|
|
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
|
|
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
|
|
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
|
|
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
|
|
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
|
|
THE SOFTWARE.
|
|
*******************************************************************************/
|
|
|
|
#include "libm.h"
|
|
#include "libm_util.h"
|
|
|
|
#define USE_HANDLE_ERRORF
|
|
#define USE_SPLITEXPF
|
|
#define USE_SCALEFLOAT_2
|
|
#define USE_VALF_WITH_FLAGS
|
|
#include "libm_inlines.h"
|
|
#undef USE_SPLITEXPF
|
|
#undef USE_SCALEFLOAT_2
|
|
#undef USE_VALF_WITH_FLAGS
|
|
#undef USE_HANDLE_ERRORF
|
|
|
|
#include "libm_errno.h"
|
|
|
|
#ifdef _MSC_VER
|
|
// Disable "C4163: not available as intrinsic function" warning that older
|
|
// compilers may issue here.
|
|
#pragma warning(disable:4163)
|
|
#pragma function(tanhf)
|
|
#endif
|
|
|
|
float tanhf(float x)
|
|
{
|
|
/*
|
|
The definition of tanh(x) is sinh(x)/cosh(x), which is also equivalent
|
|
to the following three formulae:
|
|
1. (exp(x) - exp(-x))/(exp(x) + exp(-x))
|
|
2. (1 - (2/(exp(2*x) + 1 )))
|
|
3. (exp(2*x) - 1)/(exp(2*x) + 1)
|
|
but computationally, some formulae are better on some ranges.
|
|
*/
|
|
static const float
|
|
thirtytwo_by_log2 = 4.6166240692e+01F, /* 0x4238aa3b */
|
|
log2_by_32_lead = 2.1659851074e-02F, /* 0x3cb17000 */
|
|
log2_by_32_tail = 9.9831822808e-07F, /* 0x3585fdf4 */
|
|
large_threshold = 10.0F; /* 0x41200000 */
|
|
|
|
unsigned int ux, aux;
|
|
float y, z, p, z1, z2, xneg;
|
|
int m;
|
|
|
|
/* Special cases */
|
|
|
|
GET_BITS_SP32(x, ux);
|
|
aux = ux & ~SIGNBIT_SP32;
|
|
if (aux < 0x39000000) /* |x| small enough that tanh(x) = x */
|
|
{
|
|
if (aux == 0)
|
|
return x; /* with no inexact */
|
|
else
|
|
return valf_with_flags(x, AMD_F_INEXACT);
|
|
}
|
|
else if (aux > 0x7f800000) /* |x| is NaN */
|
|
{
|
|
unsigned int ufx;
|
|
GET_BITS_SP32(x, ufx);
|
|
return _handle_errorf("tanhf", OP_TANH, ufx|0x00400000, _DOMAIN, 0,
|
|
EDOM, x, 0.0F, 1);
|
|
}
|
|
// return x + x;
|
|
|
|
xneg = 1.0F - 2.0F * (aux != ux);
|
|
|
|
y = xneg * x;
|
|
|
|
if (y > large_threshold)
|
|
{
|
|
/* If x is large then exp(-x) is negligible and
|
|
formula 1 reduces to plus or minus 1.0 */
|
|
z = 1.0F;
|
|
}
|
|
else if (y <= 1.0F)
|
|
{
|
|
float y2;
|
|
y2 = y*y;
|
|
|
|
if (y < 0.9F)
|
|
{
|
|
/* Use a [2,1] Remez approximation on [0,0.9]. */
|
|
z = y + y*y2*
|
|
(-0.28192806108402678e0F +
|
|
(-0.14628356048797849e-2F +
|
|
0.4891631088530669873e-4F*y2)*y2)/
|
|
(0.845784192581041099e0F +
|
|
0.3427017942262751343e0F*y2);
|
|
}
|
|
else
|
|
{
|
|
/* Use a [2,1] Remez approximation on [0.9,1]. */
|
|
z = y + y*y2*
|
|
(-0.24069858695196524e0F +
|
|
(-0.12325644183611929e-2F +
|
|
0.3827534993599483396e-4F*y2)*y2)/
|
|
(0.72209738473684982e0F +
|
|
0.292529068698052819e0F*y2);
|
|
}
|
|
}
|
|
else
|
|
{
|
|
/* Compute p = exp(2*y) + 1. The code is basically inlined
|
|
from exp_amd. */
|
|
|
|
splitexpf(2*y, 1.0F, thirtytwo_by_log2, log2_by_32_lead,
|
|
log2_by_32_tail, &m, &z1, &z2);
|
|
p = scaleFloat_2(z1 + z2, m) + 1.0F;
|
|
/* Now reconstruct tanh from p. */
|
|
z = (1.0F - 2.0F/p);
|
|
}
|
|
|
|
return xneg * z;
|
|
}
|