1 /* Math functions for i387.
2 Copyright (C) 1995, 1996, 1997 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
4 Contributed by John C. Bowman <bowman@ipp-garching.mpg.de>, 1995.
6 The GNU C Library is free software; you can redistribute it and/or
7 modify it under the terms of the GNU Library General Public License as
8 published by the Free Software Foundation; either version 2 of the
9 License, or (at your option) any later version.
11 The GNU C Library is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 Library General Public License for more details.
16 You should have received a copy of the GNU Library General Public
17 License along with the GNU C Library; see the file COPYING.LIB. If not,
18 write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
19 Boston, MA 02111-1307, USA. */
23 double exp (double __x
);
25 double exp (double __x
)
28 register double __value
, __exponent
;
30 ("fldl2e # e^x = 2^(x * log2(e))\n\t"
31 "fmul %%st(1) # x * log2(e)\n\t"
33 "frndint # int(x * log2(e))\n\t"
35 "fsub %%st(1) # fract(x * log2(e))\n\t"
36 "f2xm1 # 2^(fract(x * log2(e))) - 1\n\t"
37 : "=t" (__value
), "=u" (__exponent
) : "0" (__x
));
41 : "=t" (__value
) : "0" (__value
), "u" (__exponent
));
45 register double __val
;
48 fld1
// store 1.0 for later use
50 fldl2e
// e^x = 2^(x * log2(e))
51 fmul st
,st(1) // x * log2(e)
53 frndint
// int(x * log2(e))
54 fsub st
,st(1) // fract(x * log2(e))
56 f2xm1
// 2^(fract(x * log2(e))) - 1
57 fadd st
,st(3) // + 1.0