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      1 /*	$NetBSD: fixunssfdi.c,v 1.9 2013/02/03 01:48:53 matt Exp $	*/
      2 
      3 /*-
      4  * Copyright (c) 1992, 1993
      5  *	The Regents of the University of California.  All rights reserved.
      6  *
      7  * This software was developed by the Computer Systems Engineering group
      8  * at Lawrence Berkeley Laboratory under DARPA contract BG 91-66 and
      9  * contributed to Berkeley.
     10  *
     11  * Redistribution and use in source and binary forms, with or without
     12  * modification, are permitted provided that the following conditions
     13  * are met:
     14  * 1. Redistributions of source code must retain the above copyright
     15  *    notice, this list of conditions and the following disclaimer.
     16  * 2. Redistributions in binary form must reproduce the above copyright
     17  *    notice, this list of conditions and the following disclaimer in the
     18  *    documentation and/or other materials provided with the distribution.
     19  * 3. Neither the name of the University nor the names of its contributors
     20  *    may be used to endorse or promote products derived from this software
     21  *    without specific prior written permission.
     22  *
     23  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     24  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     25  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     26  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     27  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     28  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     29  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     30  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     31  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     32  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     33  * SUCH DAMAGE.
     34  */
     35 
     36 #include <sys/cdefs.h>
     37 #if defined(LIBC_SCCS) && !defined(lint)
     38 #if 0
     39 static char sccsid[] = "@(#)fixunssfdi.c	8.1 (Berkeley) 6/4/93";
     40 #else
     41 __RCSID("$NetBSD: fixunssfdi.c,v 1.9 2013/02/03 01:48:53 matt Exp $");
     42 #endif
     43 #endif /* LIBC_SCCS and not lint */
     44 
     45 #if defined(SOFTFLOAT) || defined(__ARM_EABI__)
     46 #include "softfloat/softfloat-for-gcc.h"
     47 #endif
     48 
     49 #include "quad.h"
     50 
     51 #define	ONE_FOURTH	((int)1 << (unsigned int)(INT_BITS - 2))
     52 #define	ONE_HALF	(ONE_FOURTH * 2.0)
     53 #define	ONE		(ONE_FOURTH * 4.0)
     54 
     55 /*
     56  * Convert float to (unsigned) quad.  We do most of our work in double,
     57  * out of sheer paranoia.
     58  *
     59  * Not sure what to do with negative numbers---for now, anything out
     60  * of range becomes UQUAD_MAX.
     61  *
     62  * N.B.: must use new ANSI syntax (sorry).
     63  */
     64 u_quad_t
     65 __fixunssfdi(float f)
     66 {
     67 	double x, toppart;
     68 	union uu t;
     69 
     70 	if (f < 0)
     71 		return (UQUAD_MAX);	/* ??? should be 0?  ERANGE??? */
     72 #ifdef notdef				/* this falls afoul of a GCC bug */
     73 	if (f >= UQUAD_MAX)
     74 		return (UQUAD_MAX);
     75 #else					/* so we wire in 2^64-1 instead */
     76 	if (f >= 18446744073709551615.0)	/* XXX */
     77 		return (UQUAD_MAX);
     78 #endif
     79 	x = f;
     80 	/*
     81 	 * Get the upper part of the result.  Note that the divide
     82 	 * may round up; we want to avoid this if possible, so we
     83 	 * subtract `1/2' first.
     84 	 */
     85 	toppart = (x - ONE_HALF) / ONE;
     86 	/*
     87 	 * Now build a u_quad_t out of the top part.  The difference
     88 	 * between x and this is the bottom part (this may introduce
     89 	 * a few fuzzy bits, but what the heck).  With any luck this
     90 	 * difference will be nonnegative: x should wind up in the
     91 	 * range [0..UINT_MAX].  For paranoia, we assume [INT_MIN..
     92 	 * 2*UINT_MAX] instead.
     93 	 */
     94 	t.ul[H] = (unsigned int)toppart;
     95 	t.ul[L] = 0;
     96 	x -= (double)t.uq;
     97 	if (x < 0) {
     98 		t.ul[H]--;
     99 		x += UINT_MAX;
    100 	}
    101 	if (x > UINT_MAX) {
    102 		t.ul[H]++;
    103 		x -= UINT_MAX;
    104 	}
    105 	t.ul[L] = (u_int)x;
    106 	return (t.uq);
    107 }
    108