i32_div32.c

/*
 * Copyright (c) 2016 Thomas Pornin <[email protected]>
 *
 * Permission is hereby granted, free of charge, to any person obtaining 
 * a copy of this software and associated documentation files (the
 * "Software"), to deal in the Software without restriction, including
 * without limitation the rights to use, copy, modify, merge, publish,
 * distribute, sublicense, and/or sell copies of the Software, and to
 * permit persons to whom the Software is furnished to do so, subject to
 * the following conditions:
 *
 * The above copyright notice and this permission notice shall be 
 * included in all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, 
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND 
 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
 * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
 * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */

#include "inner.h"

/* see inner.h */
uint32_t
br_divrem(uint32_t hi, uint32_t lo, uint32_t d, uint32_t *r)
{
	/* TODO: optimize this */
	uint32_t q;
	uint32_t ch, cf;
	int k;

	q = 0;
	ch = EQ(hi, d);
	hi = MUX(ch, 0, hi);
	for (k = 31; k > 0; k --) {
		int j;
		uint32_t w, ctl, hi2, lo2;

		j = 32 - k;
		w = (hi << j) | (lo >> k);
		ctl = GE(w, d) | (hi >> k);
		hi2 = (w - d) >> j;
		lo2 = lo - (d << k);
		hi = MUX(ctl, hi2, hi);
		lo = MUX(ctl, lo2, lo);
		q |= ctl << k;
	}
	cf = GE(lo, d) | hi;
	q |= cf;
	*r = MUX(cf, lo - d, lo);
	return q;
}