lib/libc/quad/floatunditf_ieee754.c

   1 /*      $NetBSD: floatunditf_ieee754.c,v 1.4 2012/08/05 04:28:58 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[] = "@(#)floatunsdidf.c      8.1 (Berkeley) 6/4/93";
  40 #else
  41 __RCSID("$NetBSD: floatunditf_ieee754.c,v 1.4 2012/08/05 04:28:58 matt Exp $");
  42 #endif
  43 #endif /* LIBC_SCCS and not lint */
  44
  45 #ifdef SOFTFLOAT
  46 #include "softfloat/softfloat-for-gcc.h"
  47 #endif
  48
  49 #include "quad.h"
  50 #ifdef __vax__
  51 #error vax does not support a distinct long double
  52 #endif
  53 #include <machine/ieee.h>
  54
  55 /*
  56  * Convert (unsigned) quad to long double.
  57  * This is exactly like floatdidf.c except that negatives never occur.
  58  */
  59 long double
  60 __floatunditf(u_quad_t x)
  61 {
  62 #if 0
  63         long double ld;
  64         union uu u;
  65
  66         u.uq = x;
  67         ld = (long double)u.ul[H] * (((int)1 << (INT_BITS - 2)) * 4.0);
  68         ld += u.ul[L];
  69         return (ld);
  70 #else
  71         union ieee_ext_u extu;
  72         quad_t tmp = x;         /* must be signed */
  73         unsigned int width = 64;
  74         unsigned int bit = 0;
  75         quad_t mask = ~(quad_t)0;
  76
  77         if (x == 0)
  78                 return 0.0L;
  79         if (x == 1)
  80                 return 1.0L;
  81
  82         while (mask != 0 && (tmp >= 0)) {
  83                 width >>= 1;
  84                 mask <<= width;
  85                 if ((tmp & mask) == 0) {
  86                         tmp <<= width;
  87                         bit += width;
  88                 }
  89         }
  90
  91         x <<= (bit + 1);
  92         extu.extu_sign = 0;
  93         extu.extu_exp = EXT_EXP_BIAS + (64 - (bit + 1));
  94         extu.extu_frach = (unsigned int)(x >> (64 - EXT_FRACHBITS));
  95         x <<= EXT_FRACHBITS;
  96 #ifdef EXT_FRACHMBITS
  97         extu.extu_frachm =(unsigned int)(x >> (64 - EXT_FRACHMBITS));
  98         x <<= EXT_FRACHMBITS;
  99 #endif
 100 #ifdef EXT_FRACLMBITS
 101         extu.extu_fraclm =(unsigned int)(x >> (64 - EXT_FRACLMBITS));
 102         x <<= EXT_FRACLMBITS;
 103 #endif
 104         extu.extu_fracl =(unsigned int)(x >> (64 - EXT_FRACLBITS));
 105
 106         return extu.extu_ld;
 107 #endif
 108 }