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