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 <sys/cdefs.h> 15 __RCSID("$NetBSD: s_truncl.c,v 1.4 2013/11/13 12:58:11 joerg Exp $"); 16 #if 0 17 __FBSDID("$FreeBSD: head/lib/msun/src/s_truncl.c 176280 2008-02-14 15:10:34Z bde $"); 18 #endif 19 20 /* 21 * truncl(x) 22 * Return x rounded toward 0 to integral value 23 * Method: 24 * Bit twiddling. 25 * Exception: 26 * Inexact flag raised if x not equal to truncl(x). 27 */ 28 #include "namespace.h" 29 30 #include <float.h> 31 #include <math.h> 32 #include <stdint.h> 33 #include <machine/ieee.h> 34 35 #ifdef __HAVE_LONG_DOUBLE 36 37 #ifdef __weak_alias 38 __weak_alias(truncl, _truncl) 39 #endif 40 41 #ifdef LDBL_IMPLICIT_NBIT 42 #define MANH_SIZE (EXT_FRACHBITS + 1) 43 #else 44 #define MANH_SIZE EXT_FRACHBITS 45 #endif 46 47 static const long double huge = 1.0e300; 48 static const float zero[] = { 0.0, -0.0 }; 49 50 long double 51 truncl(long double x) 52 { 53 union ieee_ext_u ux = { .extu_ld = x, }; 54 int e = ux.extu_exp - LDBL_MAX_EXP + 1; 55 56 if (e < MANH_SIZE - 1) { 57 if (e < 0) { /* raise inexact if x != 0 */ 58 if (huge + x > 0.0) 59 ux.extu_ld = zero[ux.extu_sign]; 60 } else { 61 uint64_t m = ((1llu << MANH_SIZE) - 1) >> (e + 1); 62 if (((ux.extu_frach & m) | ux.extu_fracl) == 0) 63 return (x); /* x is integral */ 64 if (huge + x > 0.0) { /* raise inexact flag */ 65 ux.extu_frach &= ~m; 66 ux.extu_fracl = 0; 67 } 68 } 69 } else if (e < LDBL_MANT_DIG - 1) { 70 uint64_t m = (uint64_t)-1 >> (64 - LDBL_MANT_DIG + e + 1); 71 if ((ux.extu_fracl & m) == 0) 72 return (x); /* x is integral */ 73 if (huge + x > 0.0) /* raise inexact flag */ 74 ux.extu_fracl &= ~m; 75 } 76 return (ux.extu_ld); 77 } 78 79 #endif /* __HAVE_LONG_DOUBLE */ 80