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/* $OpenBSD: poly_sin.c,v 1.1 1996/08/27 10:32:55 downsj Exp $ */
/*
* poly_sin.c
*
* Computation of an approximation of the sin function by a polynomial
*
*
* Copyright (C) 1992,1993,1994
* W. Metzenthen, 22 Parker St, Ormond, Vic 3163,
* Australia. E-mail billm@vaxc.cc.monash.edu.au
* All rights reserved.
*
* This copyright notice covers the redistribution and use of the
* FPU emulator developed by W. Metzenthen. It covers only its use
* in the 386BSD, FreeBSD and NetBSD operating systems. Any other
* use is not permitted under this copyright.
*
* 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 include information specifying
* that source code for the emulator is freely available and include
* either:
* a) an offer to provide the source code for a nominal distribution
* fee, or
* b) list at least two alternative methods whereby the source
* can be obtained, e.g. a publically accessible bulletin board
* and an anonymous ftp site from which the software can be
* downloaded.
* 3. All advertising materials specifically mentioning features or use of
* this emulator must acknowledge that it was developed by W. Metzenthen.
* 4. The name of W. Metzenthen may not be used to endorse or promote
* products derived from this software without specific prior written
* permission.
*
* THIS SOFTWARE IS PROVIDED ``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
* W. METZENTHEN 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.
*
*
* The purpose of this copyright, based upon the Berkeley copyright, is to
* ensure that the covered software remains freely available to everyone.
*
* The software (with necessary differences) is also available, but under
* the terms of the GNU copyleft, for the Linux operating system and for
* the djgpp ms-dos extender.
*
* W. Metzenthen June 1994.
*
*
* $FreeBSD: poly_sin.c,v 1.5 1994/08/31 04:45:22 davidg Exp $
*
*/
#include <gnu/arch/i386/fpemul/exception.h>
#include <gnu/arch/i386/fpemul/reg_constant.h>
#include <gnu/arch/i386/fpemul/fpu_emu.h>
#include <gnu/arch/i386/fpemul/control_w.h>
#define HIPOWER 5
static unsigned short lterms[HIPOWER][4] =
{
{0x846a, 0x42d1, 0xb544, 0x921f},
{0xe110, 0x75aa, 0xbc67, 0x1466},
{0x503d, 0xa43f, 0x83c1, 0x000a},
{0x8f9d, 0x7a19, 0x00f4, 0x0000},
{0xda03, 0x06aa, 0x0000, 0x0000},
};
static unsigned short negterms[HIPOWER][4] =
{
{0x95ed, 0x2df2, 0xe731, 0xa55d},
{0xd159, 0xe62b, 0xd2cc, 0x0132},
{0x6342, 0xe9fb, 0x3c60, 0x0000},
{0x6256, 0xdf5a, 0x0002, 0x0000},
{0xf279, 0x000b, 0x0000, 0x0000},
};
/*--- poly_sine() -----------------------------------------------------------+
| |
+---------------------------------------------------------------------------*/
void
poly_sine(FPU_REG * arg, FPU_REG * result)
{
short exponent;
FPU_REG Xx, Xx2, Xx4, accum, negaccum;
exponent = arg->exp - EXP_BIAS;
if (arg->tag == TW_Zero) {
/* Return 0.0 */
reg_move(&CONST_Z, result);
return;
}
#ifdef PARANOID
if (arg->sign != 0) { /* Can't hack a number < 0.0 */
EXCEPTION(EX_Invalid);
reg_move(&CONST_QNaN, result);
return;
}
if (exponent >= 0) { /* Can't hack a number > 1.0 */
if ((exponent == 0) && (arg->sigl == 0) && (arg->sigh == 0x80000000)) {
reg_move(&CONST_1, result);
return;
}
EXCEPTION(EX_Invalid);
reg_move(&CONST_QNaN, result);
return;
}
#endif /* PARANOID */
Xx.sigl = arg->sigl;
Xx.sigh = arg->sigh;
if (exponent < -1) {
/* shift the argument right by the required places */
if (shrx(&(Xx.sigl), -1 - exponent) >= (unsigned)0x80000000)
(*((long long *) (&(Xx.sigl))))++; /* round up */
}
mul64((long long *) &(Xx.sigl), (long long *) &(Xx.sigl),
(long long *) &(Xx2.sigl));
mul64((long long *) &(Xx2.sigl), (long long *) &(Xx2.sigl),
(long long *) &(Xx4.sigl));
/* will be a valid positive nr with expon = 0 */
*(short *) &(accum.sign) = 0;
accum.exp = 0;
/* Do the basic fixed point polynomial evaluation */
polynomial((u_int *) &(accum.sigl), (u_int *)&(Xx4.sigl), lterms, HIPOWER - 1);
/* will be a valid positive nr with expon = 0 */
*(short *) &(negaccum.sign) = 0;
negaccum.exp = 0;
/* Do the basic fixed point polynomial evaluation */
polynomial((u_int *) &(negaccum.sigl), (u_int *)&(Xx4.sigl), negterms, HIPOWER - 1);
mul64((long long *) &(Xx2.sigl), (long long *) &(negaccum.sigl),
(long long *) &(negaccum.sigl));
/* Subtract the mantissas */
*((long long *) (&(accum.sigl))) -= *((long long *) (&(negaccum.sigl)));
/* Convert to 64 bit signed-compatible */
accum.exp = EXP_BIAS - 1 + accum.exp;
*(short *) &(result->sign) = *(short *) &(accum.sign);
result->exp = accum.exp;
result->sigl = accum.sigl;
result->sigh = accum.sigh;
normalize(result);
reg_mul(result, arg, result, FULL_PRECISION);
reg_u_add(result, arg, result, FULL_PRECISION);
/* A small overflow may be possible... but an illegal result. */
if (result->exp >= EXP_BIAS) {
if ((result->exp > EXP_BIAS) /* Larger or equal 2.0 */
||(result->sigl > 1) /* Larger than 1.0+msb */
||(result->sigh != 0x80000000) /* Much > 1.0 */
) {
#ifdef DEBUGGING
RE_ENTRANT_CHECK_OFF
printk("\nEXP=%d, MS=%08x, LS=%08x\n", result->exp,
result->sigh, result->sigl);
RE_ENTRANT_CHECK_ON
#endif /* DEBUGGING */
EXCEPTION(EX_INTERNAL | 0x103);
}
#ifdef DEBUGGING
RE_ENTRANT_CHECK_OFF
printk("\n***CORRECTING ILLEGAL RESULT*** in poly_sin() computation\n");
printk("EXP=%d, MS=%08x, LS=%08x\n", result->exp,
result->sigh, result->sigl);
RE_ENTRANT_CHECK_ON
#endif /* DEBUGGING */
result->sigl = 0; /* Truncate the result to 1.00 */
}
}
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