180 lines
5.9 KiB
C
180 lines
5.9 KiB
C
/*
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* poly_sin.c
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*
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* Computation of an approximation of the sin function by a polynomial
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*
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*
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* Copyright (C) 1992, 1993 W. Metzenthen, 22 Parker St, Ormond,
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* Vic 3163, Australia.
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* E-mail apm233m@vaxc.cc.monash.edu.au
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* All rights reserved.
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*
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* This copyright notice covers the redistribution and use of the
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* FPU emulator developed by W. Metzenthen. It covers only its use
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* in the 386BSD operating system. Any other use is not permitted
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* under this copyright.
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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 include information specifying
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* that source code for the emulator is freely available and include
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* either:
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* a) an offer to provide the source code for a nominal distribution
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* fee, or
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* b) list at least two alternative methods whereby the source
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* can be obtained, e.g. a publically accessible bulletin board
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* and an anonymous ftp site from which the software can be
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* downloaded.
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* 3. All advertising materials specifically mentioning features or use of
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* this emulator must acknowledge that it was developed by W. Metzenthen.
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* 4. The name of W. Metzenthen may not be used to endorse or promote
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* products derived from this software without specific prior written
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* permission.
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*
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* THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES,
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* INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY
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* AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
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* W. METZENTHEN BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
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* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
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* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
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* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
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* LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
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* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
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* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*
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*/
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#include "exception.h"
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#include "reg_constant.h"
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#include "fpu_emu.h"
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#include "control_w.h"
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#define HIPOWER 5
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static unsigned short lterms[HIPOWER][4] =
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{
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{0x846a, 0x42d1, 0xb544, 0x921f},
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{0xe110, 0x75aa, 0xbc67, 0x1466},
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{0x503d, 0xa43f, 0x83c1, 0x000a},
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{0x8f9d, 0x7a19, 0x00f4, 0x0000},
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{0xda03, 0x06aa, 0x0000, 0x0000},
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};
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static unsigned short negterms[HIPOWER][4] =
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{
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{0x95ed, 0x2df2, 0xe731, 0xa55d},
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{0xd159, 0xe62b, 0xd2cc, 0x0132},
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{0x6342, 0xe9fb, 0x3c60, 0x0000},
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{0x6256, 0xdf5a, 0x0002, 0x0000},
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{0xf279, 0x000b, 0x0000, 0x0000},
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};
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/*--- poly_sine() -----------------------------------------------------------+
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+---------------------------------------------------------------------------*/
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void
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poly_sine(FPU_REG * arg, FPU_REG * result)
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{
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short exponent;
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FPU_REG Xx, Xx2, Xx4, accum, negaccum;
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exponent = arg->exp - EXP_BIAS;
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if (arg->tag == TW_Zero) {
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/* Return 0.0 */
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reg_move(&CONST_Z, result);
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return;
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}
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#ifdef PARANOID
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if (arg->sign != 0) { /* Can't hack a number < 0.0 */
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EXCEPTION(EX_Invalid);
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reg_move(&CONST_QNaN, result);
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return;
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}
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if (exponent >= 0) { /* Can't hack a number > 1.0 */
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if ((exponent == 0) && (arg->sigl == 0) && (arg->sigh == 0x80000000)) {
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reg_move(&CONST_1, result);
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return;
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}
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EXCEPTION(EX_Invalid);
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reg_move(&CONST_QNaN, result);
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return;
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}
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#endif /* PARANOID */
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Xx.sigl = arg->sigl;
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Xx.sigh = arg->sigh;
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if (exponent < -1) {
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/* shift the argument right by the required places */
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if (shrx(&(Xx.sigl), -1 - exponent) >= (unsigned)0x80000000)
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(*((long long *) (&(Xx.sigl))))++; /* round up */
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}
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mul64((long long *) &(Xx.sigl), (long long *) &(Xx.sigl),
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(long long *) &(Xx2.sigl));
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mul64((long long *) &(Xx2.sigl), (long long *) &(Xx2.sigl),
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(long long *) &(Xx4.sigl));
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/* will be a valid positive nr with expon = 0 */
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*(short *) &(accum.sign) = 0;
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accum.exp = 0;
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/* Do the basic fixed point polynomial evaluation */
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polynomial((u_int *) &(accum.sigl), &(Xx4.sigl), lterms, HIPOWER - 1);
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/* will be a valid positive nr with expon = 0 */
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*(short *) &(negaccum.sign) = 0;
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negaccum.exp = 0;
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/* Do the basic fixed point polynomial evaluation */
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polynomial((u_int *) &(negaccum.sigl), &(Xx4.sigl), negterms, HIPOWER - 1);
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mul64((long long *) &(Xx2.sigl), (long long *) &(negaccum.sigl),
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(long long *) &(negaccum.sigl));
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/* Subtract the mantissas */
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*((long long *) (&(accum.sigl))) -= *((long long *) (&(negaccum.sigl)));
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/* Convert to 64 bit signed-compatible */
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accum.exp = EXP_BIAS - 1 + accum.exp;
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*(short *) &(result->sign) = *(short *) &(accum.sign);
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result->exp = accum.exp;
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result->sigl = accum.sigl;
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result->sigh = accum.sigh;
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normalize(result);
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reg_mul(result, arg, result, FULL_PRECISION);
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reg_u_add(result, arg, result, FULL_PRECISION);
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/* A small overflow may be possible... but an illegal result. */
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if (result->exp >= EXP_BIAS) {
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if ((result->exp > EXP_BIAS) /* Larger or equal 2.0 */
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||(result->sigl > 1) /* Larger than 1.0+msb */
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||(result->sigh != 0x80000000) /* Much > 1.0 */
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) {
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#ifdef DEBUGGING
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RE_ENTRANT_CHECK_OFF
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printk("\nEXP=%d, MS=%08x, LS=%08x\n", result->exp,
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result->sigh, result->sigl);
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RE_ENTRANT_CHECK_ON
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#endif /* DEBUGGING */
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EXCEPTION(EX_INTERNAL | 0x103);
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}
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#ifdef DEBUGGING
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RE_ENTRANT_CHECK_OFF
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printk("\n***CORRECTING ILLEGAL RESULT*** in poly_sin() computation\n");
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printk("EXP=%d, MS=%08x, LS=%08x\n", result->exp,
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result->sigh, result->sigl);
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RE_ENTRANT_CHECK_ON
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#endif /* DEBUGGING */
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result->sigl = 0; /* Truncate the result to 1.00 */
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}
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}
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