kolibrios-fun/contrib/sdk/sources/libc/math/f_exp.c
Sergey Semyonov (Serge) c0922248c9 rename newlib to libc
git-svn-id: svn://kolibrios.org@4872 a494cfbc-eb01-0410-851d-a64ba20cac60
2014-04-22 08:56:46 +00:00

48 lines
1.1 KiB
C

/*
* ====================================================
* Copyright (C) 1998,2002 by Red Hat Inc. All rights reserved.
*
* Permission to use, copy, modify, and distribute this
* software is freely granted, provided that this notice
* is preserved.
* ====================================================
*/
#if !defined(_SOFT_FLOAT)
/*
Fast version of exp using Intel float instructions.
double _f_exp (double x);
Function computes e ** x. The following special cases exist:
1. if x is 0.0 ==> return 1.0
2. if x is infinity ==> return infinity
3. if x is -infinity ==> return 0.0
4. if x is NaN ==> return x
There is no error checking or setting of errno.
*/
#include <math.h>
#include <ieeefp.h>
#include "f_math.h"
double _f_exp (double x)
{
if (check_finite(x))
{
double result;
asm ("fldl2e; fmulp; fld %%st; frndint; fsub %%st,%%st(1); fxch;" \
"fchs; f2xm1; fld1; faddp; fxch; fld1; fscale; fstp %%st(1); fmulp" :
"=t"(result) : "0"(x));
return result;
}
else if (x == -infinity())
return 0.0;
return x;
}
#endif