gen/common/_base_S.c

	_base_S.c revision 7c478bd95313f5f23a4c958a745db2134aa03244
/*
 * 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
 */
#pragma ident   "%Z%%M% %I% %E% SMI"

/*
 * Copyright (c) 1988 by Sun Microsystems, Inc.
 */

#include "base_conversion.h"

/*  Fundamental utilities for base conversion that should be recoded as assembly language subprograms or as inline expansion templates. */

void
_fourdigitsquick(t, d)
    short unsigned  t;
    char            *d;

/* Converts t < 10000 into four ascii digits at *pc.     */

{
    register short  i;

    i = 3;
    do {
        d[i] = '0' + t % 10;
        t = t / 10;
    }
    while (--i != -1);
}

void
_multiply_base_two_vector(n, px, py, product)
    short unsigned  n, *py;
    _BIG_FLOAT_DIGIT *px, product[3];

{
    /*
     * Given xi and yi, base 2**16 vectors of length n, computes dot
     * product
     *
     * sum (i=0,n-1) of x[i]*y[n-1-i]
     *
     * Product may fill as many as three short-unsigned buckets. Product[0]
     * is least significant, product[2] most.
     */

    unsigned long   acc, p;
    short unsigned  carry;
    int             i;

    acc = 0;
    carry = 0;
    for (i = 0; i < n; i++) {
    p=_umac(px[i],py[n - 1 - i],acc);
        if (p < acc)
            carry++;
        acc = p;
    }
    product[0] = (_BIG_FLOAT_DIGIT) (acc & 0xffff);
    product[1] = (_BIG_FLOAT_DIGIT) (acc >> 16);
    product[2] = (_BIG_FLOAT_DIGIT) (carry);
}

void
_multiply_base_ten_vector(n, px, py, product)
    short unsigned  n, *py;
    _BIG_FLOAT_DIGIT *px, product[3];

{
    /*
     * Given xi and yi, base 10**4 vectors of length n, computes dot
     * product
     *
     * sum (i=0,n-1) of x[i]*y[n-1-i]
     *
     * Product may fill as many as three short-unsigned buckets. Product[0]
     * is least significant, product[2] most.
     */

#define ABASE   3000000000  /* Base of accumulator. */

    unsigned long   acc;
    short unsigned  carry;
    int             i;

    acc = 0;
    carry = 0;
    for (i = 0; i < n; i++) {
    acc=_umac(px[i],py[n - 1 - i],acc);
        if (acc >= (unsigned long) ABASE) {
            carry++;
            acc -= ABASE;
        }
    }
    /*
     NOTE: because
        acc * <= ABASE-1,
        acc/10000 <= 299999
     which would overflow a short unsigned
     */
    product[0] = (_BIG_FLOAT_DIGIT) (acc % 10000);
    acc /= 10000;
    product[1] = (_BIG_FLOAT_DIGIT) (acc % 10000);
    acc /= 10000;
    product[2] = (_BIG_FLOAT_DIGIT) (acc + (ABASE / 100000000) * carry);
}