mirror of
https://github.com/autc04/Retro68.git
synced 2024-11-24 07:31:32 +00:00
48 lines
1.2 KiB
C
48 lines
1.2 KiB
C
|
/* s_logbl.c -- long double version of s_logb.c.
|
||
|
|
* Conversion to IEEE quad long double by Jakub Jelinek, jj@ultra.linux.cz.
|
||
|
|
*/
|
||
|
|
|
||
|
|
/*
|
||
|
|
* ====================================================
|
||
|
|
* Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
|
||
|
|
*
|
||
|
|
* Developed at SunPro, a Sun Microsystems, Inc. business.
|
||
|
|
* Permission to use, copy, modify, and distribute this
|
||
|
|
* software is freely granted, provided that this notice
|
||
|
|
* is preserved.
|
||
|
|
* ====================================================
|
||
|
|
*/
|
||
|
|
|
||
|
|
/*
|
||
|
|
* long double logbl(x)
|
||
|
|
* IEEE 754 logb. Included to pass IEEE test suite. Not recommend.
|
||
|
|
* Use ilogb instead.
|
||
|
|
*/
|
||
|
|
|
||
|
|
#include "quadmath-imp.h"
|
||
|
|
|
||
|
|
__float128
|
||
|
|
logbq (__float128 x)
|
||
|
|
{
|
||
|
|
int64_t lx, hx, ex;
|
||
|
|
|
||
|
|
GET_FLT128_WORDS64 (hx, lx, x);
|
||
|
|
hx &= 0x7fffffffffffffffLL; /* high |x| */
|
||
|
|
if ((hx | lx) == 0)
|
||
|
|
return -1.0 / fabsq (x);
|
||
|
|
if (hx >= 0x7fff000000000000LL)
|
||
|
|
return x * x;
|
||
|
|
if ((ex = hx >> 48) == 0) /* IEEE 754 logb */
|
||
|
|
{
|
||
|
|
/* POSIX specifies that denormal number is treated as
|
||
|
|
though it were normalized. */
|
||
|
|
int ma;
|
||
|
|
if (hx == 0)
|
||
|
|
ma = __builtin_clzll (lx) + 64;
|
||
|
|
else
|
||
|
|
ma = __builtin_clzll (hx);
|
||
|
|
ex -= ma - 16;
|
||
|
|
}
|
||
|
|
return (__float128) (ex - 16383);
|
||
|
|
}
|