| The Android Open Source Project | a27d2ba | 2008-10-21 07:00:00 -0700 | [diff] [blame^] | 1 | /* s_logbf.c -- float version of s_logb.c. |
| 2 | * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com. |
| 3 | */ |
| 4 | |
| 5 | /* |
| 6 | * ==================================================== |
| 7 | * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved. |
| 8 | * |
| 9 | * Developed at SunPro, a Sun Microsystems, Inc. business. |
| 10 | * Permission to use, copy, modify, and distribute this |
| 11 | * software is freely granted, provided that this notice |
| 12 | * is preserved. |
| 13 | * ==================================================== |
| 14 | */ |
| 15 | |
| 16 | #ifndef lint |
| 17 | static char rcsid[] = "$FreeBSD: src/lib/msun/src/s_logbf.c,v 1.8 2005/12/03 11:57:19 bde Exp $"; |
| 18 | #endif |
| 19 | |
| 20 | #include "math.h" |
| 21 | #include "math_private.h" |
| 22 | |
| 23 | static const float |
| 24 | two25 = 3.355443200e+07; /* 0x4c000000 */ |
| 25 | |
| 26 | float |
| 27 | logbf(float x) |
| 28 | { |
| 29 | int32_t ix; |
| 30 | GET_FLOAT_WORD(ix,x); |
| 31 | ix &= 0x7fffffff; /* high |x| */ |
| 32 | if(ix==0) return (float)-1.0/fabsf(x); |
| 33 | if(ix>=0x7f800000) return x*x; |
| 34 | if(ix<0x00800000) { |
| 35 | x *= two25; /* convert subnormal x to normal */ |
| 36 | GET_FLOAT_WORD(ix,x); |
| 37 | ix &= 0x7fffffff; |
| 38 | return (float) ((ix>>23)-127-25); |
| 39 | } else |
| 40 | return (float) ((ix>>23)-127); |
| 41 | } |