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Diffstat (limited to 'libquadmath/math/ilogbq.c')
| -rw-r--r-- | libquadmath/math/ilogbq.c | 64 |
1 files changed, 64 insertions, 0 deletions
diff --git a/libquadmath/math/ilogbq.c b/libquadmath/math/ilogbq.c new file mode 100644 index 000000000..47986f5b3 --- /dev/null +++ b/libquadmath/math/ilogbq.c @@ -0,0 +1,64 @@ +/* s_ilogbl.c -- long double version of s_ilogb.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. + * ==================================================== + */ + +#if defined(LIBM_SCCS) && !defined(lint) +static char rcsid[] = "$NetBSD: $"; +#endif + +/* ilogbl(long double x) + * return the binary exponent of non-zero x + * ilogbl(0) = FP_ILOGB0 + * ilogbl(NaN) = FP_ILOGBNAN (no signal is raised) + * ilogbl(+-Inf) = INT_MAX (no signal is raised) + */ + +#include <limits.h> +#include <math.h> +#include "quadmath-imp.h" + +#ifndef FP_ILOGB0 +# define FP_ILOGB0 INT_MIN +#endif +#ifndef FP_ILOGBNAN +# define FP_ILOGBNAN INT_MAX +#endif + +int +ilogbq (__float128 x) +{ + int64_t hx,lx; + int ix; + + GET_FLT128_WORDS64(hx,lx,x); + hx &= 0x7fffffffffffffffLL; + if(hx <= 0x0001000000000000LL) { + if((hx|lx)==0) + return FP_ILOGB0; /* ilogbl(0) = FP_ILOGB0 */ + else /* subnormal x */ + if(hx==0) { + for (ix = -16431; lx>0; lx<<=1) ix -=1; + } else { + for (ix = -16382, hx<<=15; hx>0; hx<<=1) ix -=1; + } + return ix; + } + else if (hx<0x7fff000000000000LL) return (hx>>48)-0x3fff; + else if (FP_ILOGBNAN != INT_MAX) { + /* ISO C99 requires ilogbl(+-Inf) == INT_MAX. */ + if (((hx^0x7fff000000000000LL)|lx) == 0) + return INT_MAX; + } + return FP_ILOGBNAN; +} |