Function fxBigInt_udiv

xs/sources/xsBigInt.c:1814–1916

#endif

txBigInt *fxBigInt_udiv(txMachine* the, txBigInt *q, txBigInt *a, txBigInt *b, txBigInt **r)
{
	int sw;
	txBigInt *nb, *na, *tb, *a2, *b2, *tb2, *tb3;
	int i, n, t;
	txU4 *qp, *ap, *bp;
#define mk_dword(p, i)	(((txU8)(p)[i] << mxBigIntWordSize) | (p)[i - 1])

	if (fxBigInt_ucomp(a, b) < 0) {
		if (q == NULL) {
			q = fxBigInt_alloc(the, 1);
		}
		else {
			q->sign = 0;
			q->size = 1;
		}
		q->data[0] = 0;
		if (r != NULL) {
			if (*r == NULL)
				*r = fxBigInt_dup(the, a);
			else
				fxBigInt_copy(*r, a);
			(*r)->sign = 0;
		}
		return(q);
	}

	/* CAUTION: if q is present, it must take account of normalization */
	if (q == NULL)
		q = fxBigInt_alloc(the, a->size - b->size + 2);
	if (r != NULL && *r == NULL)
		*r = fxBigInt_alloc(the, b->size);

	/* normalize */
	sw = fxBigInt_ffs(b);
	nb = fxBigInt_ulsl1(the, NULL, b, sw);
	na = fxBigInt_ulsl1(the, NULL, a, sw);
	t = nb->size - 1;	/* the size must not change from 'b' */
	n = na->size - 1;

	/* adjust size of q */
	q->size = na->size - nb->size + 1;
	fxBigInt_fill0(q);	/* set 0 to quotient */

	/* process the most significant word */
	tb = fxBigInt_ulsl1(the, NULL, nb, (n - t) * mxBigIntWordSize);	/* y*b^n */
	if (fxBigInt_ucomp(na, tb) >= 0) {
		q->data[q->size - 1]++;
		fxBigInt_sub(C_NULL, na, na, tb);
		/* since nomalization done, must be na < tb here */
	}

	/* prepare the constant for the adjustment: y_t*b + y_{t-1} */
	b2 = fxBigInt_alloc(the, 2);
	fxBigInt_makepoly(b2, nb, t);
	/* and allocate for temporary buffer */
	a2 = fxBigInt_alloc(the, 3);
	tb2 = fxBigInt_alloc(the, 3);