1 /* s_ilogbl.c -- long double version of s_ilogb.c. 2 * Conversion to 128-bit long double by Mark Kettenis, kettenis@openbsd.org. 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 /* ilogbl(long double x) 17 * return the binary exponent of non-zero x 18 * ilogb(0) = FP_ILOGB0 19 * ilogb(NaN) = FP_ILOGBNAN (no signal is raised) 20 * ilogb(inf) = INT_MAX (no signal is raised) 21 */ 22 23 #include <float.h> 24 #include <math.h> 25 26 #include "math_private.h" 27 28 int 29 ilogbl(long double x) 30 { 31 int64_t hx,lx; 32 int32_t ix; 33 34 GET_LDOUBLE_WORDS64(hx,lx,x); 35 hx &= 0x7fffffffffffffffLL; 36 if(hx<0x0001000000000000LL) { 37 if((hx|lx)==0) 38 return FP_ILOGB0; /* ilogb(0) = FP_ILOGB0 */ 39 else /* subnormal x */ 40 if(hx==0) { 41 for (ix = -16431; lx>0; lx<<=1) ix -=1; 42 } else { 43 for (ix = -16382, hx<<=15; hx>0; hx<<=1) ix -=1; 44 } 45 return ix; 46 } 47 else if (hx<0x7fff000000000000LL) return (hx>>48)-16383; 48 else if (hx>0x7fff000000000000LL || lx!=0) return FP_ILOGBNAN; 49 else return INT_MAX; 50 } 51 DEF_STD(ilogbl); 52