1 /* 2 * ==================================================== 3 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved. 4 * 5 * Developed at SunPro, a Sun Microsystems, Inc. business. 6 * Permission to use, copy, modify, and distribute this 7 * software is freely granted, provided that this notice 8 * is preserved. 9 * ==================================================== 10 * 11 * From: @(#)s_floor.c 5.1 93/09/24 12 */ 13 14 #include "cdefs-compat.h" 15 //__FBSDID("$FreeBSD: src/lib/msun/src/s_truncl.c,v 1.9 2008/02/14 15:10:34 bde Exp $"); 16 17 /* 18 * truncl(x) 19 * Return x rounded toward 0 to integral value 20 * Method: 21 * Bit twiddling. 22 * Exception: 23 * Inexact flag raised if x not equal to truncl(x). 24 */ 25 26 #include <float.h> 27 #include <openlibm_math.h> 28 #include <stdint.h> 29 30 #include "fpmath.h" 31 #include "math_private.h" 32 33 #ifdef LDBL_IMPLICIT_NBIT 34 #define MANH_SIZE (LDBL_MANH_SIZE + 1) 35 #else 36 #define MANH_SIZE LDBL_MANH_SIZE 37 #endif 38 39 static const long double huge = 1.0e300; 40 static const float zero[] = { 0.0, -0.0 }; 41 42 OLM_DLLEXPORT long double 43 truncl(long double x) 44 { 45 union IEEEl2bits u = { .e = x }; 46 int e = u.bits.exp - LDBL_MAX_EXP + 1; 47 48 if (e < MANH_SIZE - 1) { 49 if (e < 0) { /* raise inexact if x != 0 */ 50 if (huge + x > 0.0) 51 u.e = zero[u.bits.sign]; 52 } else { 53 uint64_t m = ((1llu << MANH_SIZE) - 1) >> (e + 1); 54 if (((u.bits.manh & m) | u.bits.manl) == 0) 55 return (x); /* x is integral */ 56 if (huge + x > 0.0) { /* raise inexact flag */ 57 u.bits.manh &= ~m; 58 u.bits.manl = 0; 59 } 60 } 61 } else if (e < LDBL_MANT_DIG - 1) { 62 uint64_t m = (uint64_t)-1 >> (64 - LDBL_MANT_DIG + e + 1); 63 if ((u.bits.manl & m) == 0) 64 return (x); /* x is integral */ 65 if (huge + x > 0.0) /* raise inexact flag */ 66 u.bits.manl &= ~m; 67 } 68 return (u.e); 69 } 70