minix/lib/libc/quad/floatundisf_ieee754.c

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/* $NetBSD: floatundisf_ieee754.c,v 1.2 2013/08/24 00:51:48 matt Exp $ */
/*-
* Copyright (c) 2013 The NetBSD Foundation, Inc.
* All rights reserved.
*
* This code is derived from software contributed to The NetBSD Foundation
* by Matt Thomas of 3am Software Foundry.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/
#include <sys/cdefs.h>
#if defined(LIBC_SCCS) && !defined(lint)
__RCSID("$NetBSD: floatundisf_ieee754.c,v 1.2 2013/08/24 00:51:48 matt Exp $");
#endif /* LIBC_SCCS and not lint */
#if defined(SOFTFLOAT) || defined(__ARM_EABI__)
#include "softfloat/softfloat-for-gcc.h"
#endif
#include <machine/ieee.h>
#include "quad.h"
float __floatundisf(u_quad_t);
/*
* Convert unsigned quad to float.
*/
float
__floatundisf(u_quad_t x)
{
union ieee_single_u ux = { .sngu_f = 0.0 };
if (x == 0)
return 0.0;
if (x == 1)
return 1.0;
#if defined(_LP64) || defined(__mips_n32)
u_int l = __builtin_clzll(x);
x <<= (l + 1); /* clear implicit bit */
ux.sngu_frac = x >> (64 - SNG_FRACBITS);
#else
union uu u = { .uq = x };
uint32_t frac;
u_int l;
if (u.ul[H] == 0) {
l = __builtin_clz(u.ul[L]);
frac = u.ul[L] << (l + 1); /* clear implicit bit */
l += 32;
} else {
l = __builtin_clz(u.ul[H]);
frac = u.ul[H] << (l + 1); /* clear implicit bit */
frac |= u.ul[L] >> (32 - (l + 1));
}
ux.sngu_frac = frac >> (32 - SNG_FRACBITS);
#endif
ux.sngu_exp = SNG_EXP_BIAS + 63 - l;
return ux.sngu_f;
}