| 1 | /* s_logbl.c -- long double version of s_logb.c. |
|---|
| 2 | */ |
|---|
| 3 | |
|---|
| 4 | /* |
|---|
| 5 | * ==================================================== |
|---|
| 6 | * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved. |
|---|
| 7 | * |
|---|
| 8 | * Developed at SunPro, a Sun Microsystems, Inc. business. |
|---|
| 9 | * Permission to use, copy, modify, and distribute this |
|---|
| 10 | * software is freely granted, provided that this notice |
|---|
| 11 | * is preserved. |
|---|
| 12 | * ==================================================== |
|---|
| 13 | */ |
|---|
| 14 | |
|---|
| 15 | /* |
|---|
| 16 | * long double logbl(x) |
|---|
| 17 | * IEEE 754 logb. Included to pass IEEE test suite. Not recommend. |
|---|
| 18 | * Use ilogb instead. |
|---|
| 19 | */ |
|---|
| 20 | |
|---|
| 21 | #include <math.h> |
|---|
| 22 | #include <math_private.h> |
|---|
| 23 | |
|---|
| 24 | long double |
|---|
| 25 | __logbl (long double x) |
|---|
| 26 | { |
|---|
| 27 | int32_t es, lx, ix; |
|---|
| 28 | |
|---|
| 29 | GET_LDOUBLE_WORDS (es, ix, lx, x); |
|---|
| 30 | es &= 0x7fff; /* exponent */ |
|---|
| 31 | if ((es | ix | lx) == 0) |
|---|
| 32 | return -1.0 / fabsl (x: x); |
|---|
| 33 | if (es == 0x7fff) |
|---|
| 34 | return x * x; |
|---|
| 35 | if (es == 0) /* IEEE 754 logb */ |
|---|
| 36 | { |
|---|
| 37 | /* POSIX specifies that denormal number is treated as |
|---|
| 38 | though it were normalized. */ |
|---|
| 39 | if (ix == 0) |
|---|
| 40 | es = -(__builtin_clz (lx) + 32); |
|---|
| 41 | else |
|---|
| 42 | es = -__builtin_clz (ix); |
|---|
| 43 | } |
|---|
| 44 | return (long double) (es - 16383); |
|---|
| 45 | } |
|---|
| 46 | |
|---|
| 47 | weak_alias (__logbl, logbl) |
|---|
| 48 | |
|---|
