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 #if 0 16 __FBSDID("$FreeBSD: src/lib/msun/src/s_truncl.c,v 1.9 2008/02/14 15:10:34 bde Exp $"); 17 #endif 18 19 /* 20 * truncl(x) 21 * Return x rounded toward 0 to integral value 22 * Method: 23 * Bit twiddling. 24 * Exception: 25 * Inexact flag raised if x not equal to truncl(x). 26 */ 27 28 #include <sys/types.h> 29 #include <machine/ieee.h> 30 31 #include <float.h> 32 #include <math.h> 33 #include <stdint.h> 34 35 #include "math_private.h" 36 37 #ifdef LDBL_IMPLICIT_NBIT 38 #define MANH_SIZE (EXT_FRACHBITS + 1) 39 #else 40 #define MANH_SIZE EXT_FRACHBITS 41 #endif 42 43 static const long double huge = 1.0e300; 44 static const float zero[] = { 0.0, -0.0 }; 45 46 long double 47 truncl(long double x) 48 { 49 int e, es; 50 uint32_t ix0, ix1; 51 52 GET_LDOUBLE_WORDS(es,ix0,ix1,x); 53 e = (es&0x7fff) - LDBL_MAX_EXP + 1; 54 55 if (e < MANH_SIZE - 1) { 56 if (e < 0) { /* raise inexact if x != 0 */ 57 if (huge + x > 0.0) 58 return (zero[(es&0x8000)!=0]); 59 } else { 60 uint64_t m = ((1llu << MANH_SIZE) - 1) >> (e + 1); 61 if (((ix0 & m) | ix1) == 0) 62 return (x); /* x is integral */ 63 if (huge + x > 0.0) { /* raise inexact flag */ 64 ix0 &= ~m; 65 ix1 = 0; 66 } 67 } 68 } else if (e < LDBL_MANT_DIG - 1) { 69 uint64_t m = (uint64_t)-1 >> (64 - LDBL_MANT_DIG + e + 1); 70 if ((ix1 & m) == 0) 71 return (x); /* x is integral */ 72 if (huge + x > 0.0) /* raise inexact flag */ 73 ix1 &= ~m; 74 } 75 SET_LDOUBLE_WORDS(x,es,ix0,ix1); 76 return (x); 77 } 78