[unix-history] / usr / src / cmd / lisp / subbig.c

#include "global.h"

lispval
subbig(pos,neg)
lispval pos, neg;
{
	register lispval work;
	int *sp(); lispval adbig();
	register int *mysp = sp() - 2;
	register int *ersatz = mysp;

	for(work = neg; work!=0; work = work->CDR) {
		stack(-work->i, (mysp -= 2));
	}
	mysp[3] = 0;
	return(adbig(pos,ersatz));
}
/*
 * subbig -- subtract one bignum from another.
 *
 * What this does is it negates each coefficient of a copy of the bignum
 * which is just pushed on the stack for convenience.  This may give rise
 * to a bignum which is not in canonical form, but is nonetheless a repre
 * sentation of a bignum.  Addbig then adds it to a bignum, and produces
 * a result in canonical form.
 */
Commit	Line	Data
18d1c3cd JF	1	#include "global.h"
	2
	3	lispval
	4	subbig(pos,neg)
	5	lispval pos, neg;
	6	{
	7	register lispval work;
	8	int *sp(); lispval adbig();
	9	register int *mysp = sp() - 2;
	10	register int *ersatz = mysp;
	11
	12	for(work = neg; work!=0; work = work->CDR) {
	13	stack(-work->i, (mysp -= 2));
	14	}
	15	mysp[3] = 0;
	16	return(adbig(pos,ersatz));
	17	}
	18	/*
	19	* subbig -- subtract one bignum from another.
	20	*
	21	* What this does is it negates each coefficient of a copy of the bignum
	22	* which is just pushed on the stack for convenience. This may give rise
	23	* to a bignum which is not in canonical form, but is nonetheless a repre
	24	* sentation of a bignum. Addbig then adds it to a bignum, and produces
	25	* a result in canonical form.
	26	*/