fixunsdfdi.c revision 92986
11573Srgrimes/*- 21573Srgrimes * Copyright (c) 1992, 1993 31573Srgrimes * The Regents of the University of California. All rights reserved. 41573Srgrimes * 51573Srgrimes * This software was developed by the Computer Systems Engineering group 61573Srgrimes * at Lawrence Berkeley Laboratory under DARPA contract BG 91-66 and 71573Srgrimes * contributed to Berkeley. 81573Srgrimes * 91573Srgrimes * Redistribution and use in source and binary forms, with or without 101573Srgrimes * modification, are permitted provided that the following conditions 111573Srgrimes * are met: 121573Srgrimes * 1. Redistributions of source code must retain the above copyright 131573Srgrimes * notice, this list of conditions and the following disclaimer. 141573Srgrimes * 2. Redistributions in binary form must reproduce the above copyright 151573Srgrimes * notice, this list of conditions and the following disclaimer in the 161573Srgrimes * documentation and/or other materials provided with the distribution. 171573Srgrimes * 3. All advertising materials mentioning features or use of this software 181573Srgrimes * must display the following acknowledgement: 191573Srgrimes * This product includes software developed by the University of 201573Srgrimes * California, Berkeley and its contributors. 211573Srgrimes * 4. Neither the name of the University nor the names of its contributors 221573Srgrimes * may be used to endorse or promote products derived from this software 231573Srgrimes * without specific prior written permission. 241573Srgrimes * 251573Srgrimes * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 261573Srgrimes * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 271573Srgrimes * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 281573Srgrimes * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 291573Srgrimes * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 301573Srgrimes * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 311573Srgrimes * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 321573Srgrimes * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 331573Srgrimes * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 341573Srgrimes * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 351573Srgrimes * SUCH DAMAGE. 361573Srgrimes */ 371573Srgrimes 381573Srgrimes#if defined(LIBC_SCCS) && !defined(lint) 391573Srgrimesstatic char sccsid[] = "@(#)fixunsdfdi.c 8.1 (Berkeley) 6/4/93"; 401573Srgrimes#endif /* LIBC_SCCS and not lint */ 4192986Sobrien#include <sys/cdefs.h> 4292986Sobrien__FBSDID("$FreeBSD: head/lib/libc/quad/fixunsdfdi.c 92986 2002-03-22 21:53:29Z obrien $"); 431573Srgrimes 441573Srgrimes#include "quad.h" 451573Srgrimes 461573Srgrimes#define ONE_FOURTH (1 << (LONG_BITS - 2)) 471573Srgrimes#define ONE_HALF (ONE_FOURTH * 2.0) 481573Srgrimes#define ONE (ONE_FOURTH * 4.0) 491573Srgrimes 501573Srgrimes/* 511573Srgrimes * Convert double to (unsigned) quad. 521573Srgrimes * Not sure what to do with negative numbers---for now, anything out 531573Srgrimes * of range becomes UQUAD_MAX. 541573Srgrimes */ 551573Srgrimesu_quad_t 561573Srgrimes__fixunsdfdi(x) 571573Srgrimes double x; 581573Srgrimes{ 591573Srgrimes double toppart; 601573Srgrimes union uu t; 611573Srgrimes 621573Srgrimes if (x < 0) 631573Srgrimes return (UQUAD_MAX); /* ??? should be 0? ERANGE??? */ 641573Srgrimes#ifdef notdef /* this falls afoul of a GCC bug */ 651573Srgrimes if (x >= UQUAD_MAX) 661573Srgrimes return (UQUAD_MAX); 671573Srgrimes#else /* so we wire in 2^64-1 instead */ 681573Srgrimes if (x >= 18446744073709551615.0) 691573Srgrimes return (UQUAD_MAX); 701573Srgrimes#endif 711573Srgrimes /* 721573Srgrimes * Get the upper part of the result. Note that the divide 731573Srgrimes * may round up; we want to avoid this if possible, so we 741573Srgrimes * subtract `1/2' first. 751573Srgrimes */ 761573Srgrimes toppart = (x - ONE_HALF) / ONE; 771573Srgrimes /* 781573Srgrimes * Now build a u_quad_t out of the top part. The difference 791573Srgrimes * between x and this is the bottom part (this may introduce 801573Srgrimes * a few fuzzy bits, but what the heck). With any luck this 811573Srgrimes * difference will be nonnegative: x should wind up in the 821573Srgrimes * range [0..ULONG_MAX]. For paranoia, we assume [LONG_MIN.. 831573Srgrimes * 2*ULONG_MAX] instead. 841573Srgrimes */ 851573Srgrimes t.ul[H] = (unsigned long)toppart; 861573Srgrimes t.ul[L] = 0; 871573Srgrimes x -= (double)t.uq; 881573Srgrimes if (x < 0) { 891573Srgrimes t.ul[H]--; 901573Srgrimes x += ULONG_MAX; 911573Srgrimes } 921573Srgrimes if (x > ULONG_MAX) { 931573Srgrimes t.ul[H]++; 941573Srgrimes x -= ULONG_MAX; 951573Srgrimes } 961573Srgrimes t.ul[L] = (u_long)x; 971573Srgrimes return (t.uq); 981573Srgrimes} 99