1175309Sdas/*- 2175309Sdas * Copyright (c) 2008 David Schultz <das@FreeBSD.ORG> 3175309Sdas * All rights reserved. 4175309Sdas * 5175309Sdas * Redistribution and use in source and binary forms, with or without 6175309Sdas * modification, are permitted provided that the following conditions 7175309Sdas * are met: 8175309Sdas * 1. Redistributions of source code must retain the above copyright 9175309Sdas * notice, this list of conditions and the following disclaimer. 10175309Sdas * 2. Redistributions in binary form must reproduce the above copyright 11175309Sdas * notice, this list of conditions and the following disclaimer in the 12175309Sdas * documentation and/or other materials provided with the distribution. 13175309Sdas * 14175309Sdas * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 15175309Sdas * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 16175309Sdas * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 17175309Sdas * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 18175309Sdas * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 19175309Sdas * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 20175309Sdas * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 21175309Sdas * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 22175309Sdas * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 23175309Sdas * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 24175309Sdas * SUCH DAMAGE. 25175309Sdas */ 26175309Sdas 27175309Sdas#include <sys/cdefs.h> 28175309Sdas__FBSDID("$FreeBSD$"); 29175309Sdas 30175309Sdas#include <float.h> 31175309Sdas#include <math.h> 32175309Sdas 33175309Sdas#include "fpmath.h" 34175309Sdas 35176461Sbde#if LDBL_MAX_EXP != 0x4000 36176461Sbde/* We also require the usual bias, min exp and expsign packing. */ 37176461Sbde#error "Unsupported long double format" 38176461Sbde#endif 39176461Sbde 40175371Sdas#define BIAS (LDBL_MAX_EXP - 1) 41175371Sdas 42175371Sdasstatic const float 43175371Sdasshift[2] = { 44175309Sdas#if LDBL_MANT_DIG == 64 45175309Sdas 0x1.0p63, -0x1.0p63 46175309Sdas#elif LDBL_MANT_DIG == 113 47175309Sdas 0x1.0p112, -0x1.0p112 48175309Sdas#else 49175309Sdas#error "Unsupported long double format" 50175309Sdas#endif 51175309Sdas}; 52176458Sbdestatic const float zero[2] = { 0.0, -0.0 }; 53175309Sdas 54175309Sdaslong double 55175309Sdasrintl(long double x) 56175309Sdas{ 57175309Sdas union IEEEl2bits u; 58176461Sbde uint32_t expsign; 59176461Sbde int ex, sign; 60175309Sdas 61175309Sdas u.e = x; 62176461Sbde expsign = u.xbits.expsign; 63176461Sbde ex = expsign & 0x7fff; 64175309Sdas 65176461Sbde if (ex >= BIAS + LDBL_MANT_DIG - 1) { 66176461Sbde if (ex == BIAS + LDBL_MAX_EXP) 67176456Sbde return (x + x); /* Inf, NaN, or unsupported format */ 68176456Sbde return (x); /* finite and already an integer */ 69175309Sdas } 70176461Sbde sign = expsign >> 15; 71175309Sdas 72175309Sdas /* 73175309Sdas * The following code assumes that intermediate results are 74175309Sdas * evaluated in long double precision. If they are evaluated in 75175371Sdas * greater precision, double rounding may occur, and if they are 76175309Sdas * evaluated in less precision (as on i386), results will be 77175309Sdas * wildly incorrect. 78175309Sdas */ 79175371Sdas x += shift[sign]; 80175371Sdas x -= shift[sign]; 81175371Sdas 82175371Sdas /* 83175371Sdas * If the result is +-0, then it must have the same sign as x, but 84175371Sdas * the above calculation doesn't always give this. Fix up the sign. 85175371Sdas */ 86176461Sbde if (ex < BIAS && x == 0.0L) 87176458Sbde return (zero[sign]); 88176458Sbde 89175371Sdas return (x); 90175309Sdas} 91