/* * ==================================================== * 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. * ==================================================== * * From: @(#)s_floor.c 5.1 93/09/24 */ #ifndef lint static char rcsid[] = "$FreeBSD: src/lib/msun/src/s_truncl.c,v 1.4 2005/04/28 19:45:55 stefanf Exp $"; #endif /* * truncl(x) * Return x rounded toward 0 to integral value * Method: * Bit twiddling. * Exception: * Inexact flag raised if x not equal to truncl(x). */ #include <float.h> #include <math.h> #include <stdint.h> #include "fpmath.h" #ifdef LDBL_IMPLICIT_NBIT #define MANH_SIZE (LDBL_MANH_SIZE + 1) #else #define MANH_SIZE LDBL_MANH_SIZE #endif static const long double huge = 1.0e300; long double truncl(long double x) { union IEEEl2bits u = { .e = x }; int e = u.bits.exp - LDBL_MAX_EXP + 1; if (e < MANH_SIZE - 1) { if (e < 0) { /* raise inexact if x != 0 */ if (huge + x > 0.0) u.e = 0.0; } else { uint64_t m = ((1llu << MANH_SIZE) - 1) >> (e + 1); if (((u.bits.manh & m) | u.bits.manl) == 0) return (x); /* x is integral */ if (huge + x > 0.0) { /* raise inexact flag */ u.bits.manh &= ~m; u.bits.manl = 0; } } } else if (e < LDBL_MANT_DIG - 1) { uint64_t m = (uint64_t)-1 >> (64 - LDBL_MANT_DIG + e + 1); if ((u.bits.manl & m) == 0) return (x); /* x is integral */ if (huge + x > 0.0) /* raise inexact flag */ u.bits.manl &= ~m; } return (u.e); }