glibc/sysdeps/m68k/fpu/e_pow.c

121 lines
2.7 KiB
C

/* Copyright (C) 1997 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Library General Public License as
published by the Free Software Foundation; either version 2 of the
License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Library General Public License for more details.
You should have received a copy of the GNU Library General Public
License along with the GNU C Library; see the file COPYING.LIB. If not,
write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
Boston, MA 02111-1307, USA. */
#define __LIBC_M81_MATH_INLINES
#include <math.h>
#include "math_private.h"
#ifndef SUFF
#define SUFF
#endif
#ifndef float_type
#define float_type double
#endif
#define CONCATX(a,b) __CONCAT(a,b)
#define s(name) CONCATX(name,SUFF)
#define m81(func) __m81_u(s(func))
float_type
s(__ieee754_pow) (float_type x, float_type y)
{
float_type z;
float_type ax;
if (y == 0.0)
return 1.0;
if (x != x || y != y)
return x + y;
if (m81(__isinf) (y))
{
ax = s(fabs) (x);
if (ax == 1)
return 0.0/0.0;
if (ax > 1)
return y > 0 ? y : 0;
else
return y < 0 ? -y : 0;
}
if (s(fabs) (y) == 1)
return y > 0 ? x : 1 / x;
if (y == 2)
return x * x;
if (y == 0.5 && x >= 0)
return m81(__ieee754_sqrt) (x);
if (x == 10.0)
{
__asm ("ftentox%.x %1, %0" : "=f" (z) : "f" (y));
return z;
}
if (x == 2.0)
{
__asm ("ftwotox%.x %1, %0" : "=f" (z) : "f" (y));
return z;
}
ax = s(fabs) (x);
if (m81(__isinf) (x) || x == 0 || ax == 1)
{
z = ax;
if (y < 0)
z = 1 / z;
if (m81(__signbit) (x))
{
if (y != m81(__rint) (y))
{
if (x == -1)
z = 0.0/0.0;
}
else
goto maybe_negate;
}
return z;
}
if (x < 0.0)
{
if (y == m81(__rint) (y))
{
z = m81(__ieee754_exp) (y * m81(__ieee754_log) (-x));
maybe_negate:
/* We always use the long double format, since y is already in
this format and rounding won't change the result. */
{
int32_t exponent;
u_int32_t i0, i1;
GET_LDOUBLE_WORDS (exponent, i0, i1, y);
exponent = (exponent & 0x7fff) - 0x3fff;
if (exponent <= 31
? i0 & (1 << (31 - exponent))
: (exponent <= 63
&& i1 & (1 << (63 - exponent))))
z = -z;
}
}
else
z = 0.0/0.0;
}
else
z = m81(__ieee754_exp) (y * m81(__ieee754_log) (x));
return z;
}