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Annotation of src/lib/libc/quad/floatunditf_ieee754.c, Revision 1.4

1.4     ! matt        1: /*     $NetBSD: floatunditf_ieee754.c,v 1.3 2012/03/25 19:53:18 christos Exp $ */
1.1       matt        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
1.4     ! matt       41: __RCSID("$NetBSD: floatunditf_ieee754.c,v 1.3 2012/03/25 19:53:18 christos Exp $");
1.1       matt       42: #endif
                     43: #endif /* LIBC_SCCS and not lint */
                     44:
1.4     ! matt       45: #ifdef SOFTFLOAT
        !            46: #include "softfloat/softfloat-for-gcc.h"
        !            47: #endif
        !            48:
1.1       matt       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;
1.2       matt       72:        quad_t tmp = x;         /* must be signed */
1.3       christos   73:        unsigned int width = 64;
                     74:        unsigned int bit = 0;
1.2       matt       75:        quad_t mask = ~(quad_t)0;
1.1       matt       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));
1.3       christos   94:        extu.extu_frach = (unsigned int)(x >> (64 - EXT_FRACHBITS));
1.1       matt       95:        x <<= EXT_FRACHBITS;
                     96: #ifdef EXT_FRACHMBITS
1.3       christos   97:        extu.extu_frachm =(unsigned int)(x >> (64 - EXT_FRACHMBITS));
1.1       matt       98:        x <<= EXT_FRACHMBITS;
                     99: #endif
                    100: #ifdef EXT_FRACLMBITS
1.3       christos  101:        extu.extu_fraclm =(unsigned int)(x >> (64 - EXT_FRACLMBITS));
1.1       matt      102:        x <<= EXT_FRACLMBITS;
                    103: #endif
1.3       christos  104:        extu.extu_fracl =(unsigned int)(x >> (64 - EXT_FRACLBITS));
1.1       matt      105:
                    106:        return extu.extu_ld;
                    107: #endif
                    108: }