81 lines
2.5 KiB
C
81 lines
2.5 KiB
C
/* $NetBSD: lroundf.c,v 1.3 2008/04/26 23:49:50 christos Exp $ */
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/*-
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* Copyright (c) 2004
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* Matthias Drochner. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#include <math.h>
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#include <sys/ieee754.h>
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#include <machine/limits.h>
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#include "math_private.h"
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#ifndef LROUNDNAME
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#define LROUNDNAME lroundf
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#define RESTYPE long int
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#define RESTYPE_MIN LONG_MIN
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#define RESTYPE_MAX LONG_MAX
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#endif
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#define RESTYPE_BITS (sizeof(RESTYPE) * 8)
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RESTYPE
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LROUNDNAME(float x)
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{
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uint32_t i0;
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int e, s, shift;
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RESTYPE res;
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GET_FLOAT_WORD(i0, x);
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e = i0 >> SNG_FRACBITS;
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s = (uint32_t)e >> SNG_EXPBITS;
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e = (e & 0xff) - SNG_EXP_BIAS;
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/* 1.0 x 2^-1 is the smallest number which can be rounded to 1 */
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if (e < -1)
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return (0);
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/* 1.0 x 2^31 (or 2^63) is already too large */
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if (e >= (int)RESTYPE_BITS - 1)
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return (s ? RESTYPE_MIN : RESTYPE_MAX); /* ??? unspecified */
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/* >= 2^23 is already an exact integer */
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if (e < SNG_FRACBITS) {
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/* add 0.5, extraction below will truncate */
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x += (s ? -0.5 : 0.5);
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}
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GET_FLOAT_WORD(i0, x);
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e = ((i0 >> SNG_FRACBITS) & 0xff) - SNG_EXP_BIAS;
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i0 &= 0x7fffff;
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i0 |= (1 << SNG_FRACBITS);
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shift = e - SNG_FRACBITS;
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if (shift >=0)
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res = (shift < 32 ? (RESTYPE)i0 << shift : 0);
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else
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res = (shift > -32 ? i0 >> -shift : 0);
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return (s ? -res : res);
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}
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