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Diffstat (limited to 'libm/s_logb.c')
| -rw-r--r-- | libm/s_logb.c | 44 |
1 files changed, 44 insertions, 0 deletions
diff --git a/libm/s_logb.c b/libm/s_logb.c new file mode 100644 index 000000000..7ec1c3696 --- /dev/null +++ b/libm/s_logb.c @@ -0,0 +1,44 @@ +#if !defined(__ppc__) +/* @(#)s_logb.c 5.1 93/09/24 */ +/* + * ==================================================== + * 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. + * ==================================================== + */ + +#if defined(LIBM_SCCS) && !defined(lint) +static char rcsid[] = "$NetBSD: s_logb.c,v 1.8 1995/05/10 20:47:50 jtc Exp $"; +#endif + +/* + * double logb(x) + * IEEE 754 logb. Included to pass IEEE test suite. Not recommend. + * Use ilogb instead. + */ + +#include "math.h" +#include "math_private.h" + +#ifdef __STDC__ + double logb(double x) +#else + double logb(x) + double x; +#endif +{ + int32_t lx,ix; + EXTRACT_WORDS(ix,lx,x); + ix &= 0x7fffffff; /* high |x| */ + if((ix|lx)==0) return -1.0/fabs(x); + if(ix>=0x7ff00000) return x*x; + if((ix>>=20)==0) /* IEEE 754 logb */ + return -1022.0; + else + return (double) (ix-1023); +} +#endif /* !__ppc__ */ |