diff options
Diffstat (limited to 'sysdeps/ieee754/dbl-64/e_ilogb.c')
| -rw-r--r-- | sysdeps/ieee754/dbl-64/e_ilogb.c | 55 |
1 files changed, 55 insertions, 0 deletions
diff --git a/sysdeps/ieee754/dbl-64/e_ilogb.c b/sysdeps/ieee754/dbl-64/e_ilogb.c new file mode 100644 index 0000000000..7772880a1f --- /dev/null +++ b/sysdeps/ieee754/dbl-64/e_ilogb.c @@ -0,0 +1,55 @@ +/* @(#)s_ilogb.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_ilogb.c,v 1.9 1995/05/10 20:47:28 jtc Exp $"; +#endif + +/* ilogb(double x) + * return the binary exponent of non-zero x + * ilogb(0) = FP_ILOGB0 + * ilogb(NaN) = FP_ILOGBNAN (no signal is raised) + * ilogb(+-Inf) = INT_MAX (no signal is raised) + */ + +#include <limits.h> +#include <math.h> +#include <math_private.h> + +int __ieee754_ilogb(double x) +{ + int32_t hx,lx,ix; + + GET_HIGH_WORD(hx,x); + hx &= 0x7fffffff; + if(hx<0x00100000) { + GET_LOW_WORD(lx,x); + if((hx|lx)==0) + return FP_ILOGB0; /* ilogb(0) = FP_ILOGB0 */ + else /* subnormal x */ + if(hx==0) { + for (ix = -1043; lx>0; lx<<=1) ix -=1; + } else { + for (ix = -1022,hx<<=11; hx>0; hx<<=1) ix -=1; + } + return ix; + } + else if (hx<0x7ff00000) return (hx>>20)-1023; + else if (FP_ILOGBNAN != INT_MAX) { + /* ISO C99 requires ilogb(+-Inf) == INT_MAX. */ + GET_LOW_WORD(lx,x); + if(((hx^0x7ff00000)|lx) == 0) + return INT_MAX; + } + return FP_ILOGBNAN; +} +strong_alias (__ieee754_ilogb, __ilogb_finite) |