xref: /illumos-gate/usr/src/uts/sparc/fpu/mul.c (revision 7c478bd9)

/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License, Version 1.0 only
 * (the "License").  You may not use this file except in compliance
 * with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */
/*
 * Copyright (c) 1988 by Sun Microsystems, Inc.
 */

#ident	"%Z%%M%	%I%	%E% SMI"	/* SunOS-4.1 1.8 88/12/06 */

#include <sys/fpu/fpu_simulator.h>
#include <sys/fpu/globals.h>

void
_fp_mul(pfpsd, px, py, pz)
	fp_simd_type	*pfpsd;
	unpacked	*px, *py, *pz;

{
	unpacked	*pt;
	unsigned	acc[4];		/* Product accumulator. */
	unsigned	j, y, *x, s, r, c;

	if ((int) px->fpclass <= (int) py->fpclass) {
		pt = px;
		px = py;
		py = pt;
	}
	/* Now class(x) >= class(y).  */

	*pz = *px;
	if (pz->fpclass < fp_quiet)
		pz->sign = px->sign ^ py->sign;

	switch (px->fpclass) {
	case fp_quiet:
	case fp_signaling:
	case fp_zero:
		return;
	case fp_infinity:
		if (py->fpclass == fp_zero) {
			fpu_error_nan(pfpsd, pz);
			pz->fpclass = fp_quiet;
		}
		return;
	case fp_normal:
		if (py->fpclass == fp_zero) {
			pz->fpclass = fp_zero;
			return;
		}
	}

	/* Now x and y are both normal or subnormal. */

	x = px->significand;	/* save typing */

	/* intialize acc to zero */
	s = r = acc[0] = acc[1] = acc[2] = acc[3] = 0;

	y = py->significand[3];		/* py->significand[3] * x */
	if (y != 0) {
	    j = 1;
	    do {
		s |= r;		/* shift acc right one bit */
		r  = acc[3]&1;
		acc[3] = ((acc[2]&1)<<31)|(acc[3]>>1);
		acc[2] = ((acc[1]&1)<<31)|(acc[2]>>1);
		acc[1] = ((acc[0]&1)<<31)|(acc[1]>>1);
		acc[0] = (acc[0]>>1);
		if (j&y) {		/* bit i of y != 0, add x to acc */
			c = 0;
			c = fpu_add3wc(&acc[3], acc[3], x[3], c);
			c = fpu_add3wc(&acc[2], acc[2], x[2], c);
			c = fpu_add3wc(&acc[1], acc[1], x[1], c);
			c = fpu_add3wc(&acc[0], acc[0], x[0], c);
		}
		j += j;
	    } while (j != 0);
	}

	y = py->significand[2];		/* py->significand[2] * x */
	if (y != 0) {
	    j = 1;
	    do {
		s |= r;		/* shift acc right one bit */
		r  = acc[3]&1;
		acc[3] = ((acc[2]&1)<<31)|(acc[3]>>1);
		acc[2] = ((acc[1]&1)<<31)|(acc[2]>>1);
		acc[1] = ((acc[0]&1)<<31)|(acc[1]>>1);
		acc[0] = (acc[0]>>1);
		if (j&y) {		/* bit i of y != 0, add x to acc */
			c = 0;
			c = fpu_add3wc(&acc[3], acc[3], x[3], c);
			c = fpu_add3wc(&acc[2], acc[2], x[2], c);
			c = fpu_add3wc(&acc[1], acc[1], x[1], c);
			c = fpu_add3wc(&acc[0], acc[0], x[0], c);
		}
		j += j;
	    } while (j != 0);
	} else {
		s |= r|(acc[3]&0x7fffffff);
		r  = (acc[3]&0x80000000)>>31;
		acc[3] = acc[2]; acc[2] = acc[1]; acc[1] = acc[0]; acc[0] = 0;
	}

	y = py->significand[1];		/* py->significand[1] * x */
	if (y != 0) {
	    j = 1;
	    do {
		s |= r;		/* shift acc right one bit */
		r  = acc[3]&1;
		acc[3] = ((acc[2]&1)<<31)|(acc[3]>>1);
		acc[2] = ((acc[1]&1)<<31)|(acc[2]>>1);
		acc[1] = ((acc[0]&1)<<31)|(acc[1]>>1);
		acc[0] = (acc[0]>>1);
		if (j&y) {		/* bit i of y != 0, add x to acc */
			c = 0;
			c = fpu_add3wc(&acc[3], acc[3], x[3], c);
			c = fpu_add3wc(&acc[2], acc[2], x[2], c);
			c = fpu_add3wc(&acc[1], acc[1], x[1], c);
			c = fpu_add3wc(&acc[0], acc[0], x[0], c);
		}
		j += j;
	    } while (j != 0);
	} else {
		s |= r|(acc[3]&0x7fffffff);
		r  = (acc[3]&0x80000000)>>31;
		acc[3] = acc[2]; acc[2] = acc[1]; acc[1] = acc[0]; acc[0] = 0;
	}

					/* py->significand[0] * x */
	y = py->significand[0];		/* y is of form 0x0001???? */
	j = 1;
	do {
		s |= r;		/* shift acc right one bit */
		r  = acc[3]&1;
		acc[3] = ((acc[2]&1)<<31)|(acc[3]>>1);
		acc[2] = ((acc[1]&1)<<31)|(acc[2]>>1);
		acc[1] = ((acc[0]&1)<<31)|(acc[1]>>1);
		acc[0] = (acc[0]>>1);
		if (j&y) {		/* bit i of y != 0, add x to acc */
			c = 0;
			c = fpu_add3wc(&acc[3], acc[3], x[3], c);
			c = fpu_add3wc(&acc[2], acc[2], x[2], c);
			c = fpu_add3wc(&acc[1], acc[1], x[1], c);
			c = fpu_add3wc(&acc[0], acc[0], x[0], c);
		}
		j += j;
	} while (j <= y);

	if (acc[0] >= 0x20000) {	/* right shift one bit to normalize */
		pz->exponent = px->exponent + py->exponent + 1;
		pz->sticky = s|r;
		pz->rounded = acc[3]&1;
		pz->significand[3] = ((acc[2]&1)<<31)|(acc[3]>>1);
		pz->significand[2] = ((acc[1]&1)<<31)|(acc[2]>>1);
		pz->significand[1] = ((acc[0]&1)<<31)|(acc[1]>>1);
		pz->significand[0] = (acc[0]>>1);
	} else {
		pz->exponent = px->exponent + py->exponent;
		pz->sticky = s;
		pz->rounded = r;
		pz->significand[3] = acc[3];
		pz->significand[2] = acc[2];
		pz->significand[1] = acc[1];
		pz->significand[0] = acc[0];
	}
}