i32_decode.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 */
void
br_i32_decode(uint32_t *x, const void *src, size_t len)
{
	const unsigned char *buf;
	size_t u, v;

	buf = src;
	u = len;
	v = 1;
	for (;;) {
		if (u < 4) {
			uint32_t w;

			if (u < 2) {
				if (u == 0) {
					break;
				} else {
					w = buf[0];
				}
			} else {
				if (u == 2) {
					w = br_dec16be(buf);
				} else {
					w = ((uint32_t)buf[0] << 16)
						| br_dec16be(buf + 1);
				}
			}
			x[v ++] = w;
			break;
		} else {
			u -= 4;
			x[v ++] = br_dec32be(buf + u);
		}
	}
	x[0] = br_i32_bit_length(x + 1, v - 1);
}