Function fxBigInt_sqr

xs/sources/xsBigInt.c:1671–1716

}

txBigInt *fxBigInt_sqr(txMachine* the, txBigInt *r, txBigInt *a)
{
	int i, j, t;
	txU4 *ap, *rp;
	txU8 uv, t1, t2, t3, ai;
	txU4 c, cc;
	txU4 overflow = 0;	/* overflow flag of 'u' */

	if (r == NULL)
		r = fxBigInt_alloc(the, a->size * 2);
	fxBigInt_fill0(r);
	t = a->size;
	ap = a->data;
	rp = r->data;

	for (i = 0; i < t - 1; i++) {
		uv = (txU8)ap[i] * ap[i] + rp[i * 2];
		rp[i * 2] = mxBigIntLowWord(uv);
		c = mxBigIntHighWord(uv);
		cc = 0;
		ai = ap[i];
		for (j = i + 1; j < t; j++) {
			int k = i + j;
			t1 = ai * ap[j];
			t2 = t1 + c + ((txU8)cc << mxBigIntWordSize);	/* 'cc:c' must be <= 2(b-1) so no overflow here */
			t3 = t1 + t2;
			uv = t3 + rp[k];
			cc = t3 < t1 || uv < t3;
			c = (txU4)mxBigIntHighWord(uv);
			rp[k] = mxBigIntLowWord(uv);
		}
		c += overflow;
		rp[i + t] = c;		/* c = u */
		overflow = cc || c < overflow;
	}
	/* the last loop */
	uv = (txU8)ap[i] * ap[i] + rp[i * 2];
	rp[i * 2] = mxBigIntLowWord(uv);
	rp[i + t] = mxBigIntHighWord(uv) + overflow;

	/* remove leading 0s */
	for (i = 2*t; --i > 0 && rp[i] == 0;)
		;
	r->size = i + 1;
	return(r);
}

txBigInt *fxBigInt_div(txMachine* the, txBigInt *q, txBigInt *a, txBigInt *b)
{