1 /* $OpenBSD: s_lrint.c,v 1.1 2006/09/25 20:25:41 kettenis Exp $ */ 2 /* $NetBSD: lrint.c,v 1.3 2004/10/13 15:18:32 drochner Exp $ */ 3 4 /*- 5 * Copyright (c) 2004 6 * Matthias Drochner. All rights reserved. 7 * 8 * Redistribution and use in source and binary forms, with or without 9 * modification, are permitted provided that the following conditions 10 * are met: 11 * 1. Redistributions of source code must retain the above copyright 12 * notice, this list of conditions and the following disclaimer. 13 * 2. Redistributions in binary form must reproduce the above copyright 14 * notice, this list of conditions and the following disclaimer in the 15 * documentation and/or other materials provided with the distribution. 16 * 17 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 20 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 27 * SUCH DAMAGE. 28 */ 29 30 #include <sys/types.h> 31 #include <sys/limits.h> 32 #include <math.h> 33 #include <ieeefp.h> 34 #include <machine/ieee.h> 35 #include "math_private.h" 36 37 #ifndef LRINTNAME 38 #define LRINTNAME lrint 39 #define RESTYPE long int 40 #define RESTYPE_MIN LONG_MIN 41 #define RESTYPE_MAX LONG_MAX 42 #endif 43 44 #define RESTYPE_BITS (sizeof(RESTYPE) * 8) 45 46 static const double 47 TWO52[2]={ 48 4.50359962737049600000e+15, /* 0x43300000, 0x00000000 */ 49 -4.50359962737049600000e+15, /* 0xC3300000, 0x00000000 */ 50 }; 51 52 RESTYPE 53 LRINTNAME(double x) 54 { 55 u_int32_t i0, i1; 56 int e, s, shift; 57 RESTYPE res; 58 59 GET_HIGH_WORD(i0, x); 60 e = i0 >> 20; 61 s = e >> DBL_EXPBITS; 62 e = (e & 0x7ff) - DBL_EXP_BIAS; 63 64 /* 1.0 x 2^-1 is the smallest number which can be rounded to 1 */ 65 if (e < -1) 66 return (0); 67 /* 1.0 x 2^31 (or 2^63) is already too large */ 68 if (e >= (int)RESTYPE_BITS - 1) 69 return (s ? RESTYPE_MIN : RESTYPE_MAX); /* ??? unspecified */ 70 71 /* >= 2^52 is already an exact integer */ 72 if (e < DBL_FRACBITS) { 73 /* round, using current direction */ 74 x += TWO52[s]; 75 x -= TWO52[s]; 76 } 77 78 EXTRACT_WORDS(i0, i1, x); 79 e = ((i0 >> 20) & 0x7ff) - DBL_EXP_BIAS; 80 i0 &= 0xfffff; 81 i0 |= (1 << 20); 82 83 shift = e - DBL_FRACBITS; 84 if (shift >=0) 85 res = (shift < 32 ? (RESTYPE)i1 << shift : 0); 86 else 87 res = (shift > -32 ? i1 >> -shift : 0); 88 shift += 32; 89 if (shift >=0) 90 res |= (shift < 32 ? (RESTYPE)i0 << shift : 0); 91 else 92 res |= (shift > -32 ? i0 >> -shift : 0); 93 94 return (s ? -res : res); 95 } 96