Return to sdiv.c CVS log

Up to [MW Coherent from dump] / coherent / d / usr / lib / libmp

coherent

#include "mprec.h"
#include <assert.h>


/*
 *	Sdiv divides the mint pointed to by "a" by the int "n".  It sets
 *	the mint pointed to by "q" to the quotient and the int pointed to
 *	by "r" to the remainder.
 *	Note that it is assumed that 1 <= "n" <= BASE.
 *	The division is performed such that the following two properties
 *	hold :
 *		1. r + q * n = a.
 *		2. the sign of r = the sign of q.
 *		3. the abs. value of r < the abs. value of b.
 *	Note that "a" == "q" is permissable.
 */

void
sdiv(a, n, q, r)
mint *a, *q;
register int n;
int *r;
{
	register char	*qp, *ap;
	char	*res;
	int	npfl;	/* numerator positive flag */
	char	dmfl;	/* denominator minus flag */
	mint	al;
	register int	rem;

	if (n == 0)
		mperr("division by zero attempted");
	if (dmfl = n < 0)
		n = -n;
	assert(1 <= n && n <= BASE);

	/* set npfl and negate a if necessary */
	npfl = ispos(a);
	if (!npfl) {
		minit(&al);
		mneg(a, &al);
		a = &al;
	}

	/* allocate space for result */
	res = (char *)mpalc(a->len);

	/* compute quotient, most sig. digit first */
	qp = res + a->len;
	ap = a->val + a->len;
	rem = 0;
	while (qp > res) {
		rem = BASE * rem + *--ap;
		*--qp = rem / n;
		rem %= n;
	}
	mpfree(q->val);
	q->val = res;
	q->len = a->len;
	norm(q);

	/* fix up sign if a was negative */
	if (npfl ? dmfl : !dmfl) {
		rem = -rem;
		mneg(q, q);
	}
	if (!npfl)
		mpfree(al.val);
	*r = rem;
}

This archive runs on limited infrastructure. Preserving old code on modern bandwidth. Automated agents are requested to crawl responsibly.