/*

 * Copyright (C) the libgit2 contributors. All rights reserved.

 *

 * This file is part of libgit2, distributed under the GNU GPL v2 with

 * a Linking Exception. For full terms see the included COPYING file.

 */

#include "common.h"

#include "varint.h"

uintmax_t git_decode_varint(const unsigned char *bufp, size_t *varint_len)

{

	const unsigned char *buf = bufp;

	unsigned char c = *buf++;

	uintmax_t val = c & 127;

	while (c & 128) {

		val += 1;

		if (!val || MSB(val, 7)) {

			/* This is not a valid varint_len, so it signals

			   the error */

			*varint_len = 0;

			return 0; /* overflow */

		}

		c = *buf++;

		val = (val << 7) + (c & 127);

	}

	*varint_len = buf - bufp;

	return val;

}

int git_encode_varint(unsigned char *buf, size_t bufsize, uintmax_t value)

{

	unsigned char varint[16];

	unsigned pos = sizeof(varint) - 1;

	varint[pos] = value & 127;

	while (value >>= 7)

		varint[--pos] = 128 | (--value & 127);

	if (buf) {

		if (bufsize < (sizeof(varint) - pos))

			return -1;

		memcpy(buf, varint + pos, sizeof(varint) - pos);

	}

	return sizeof(varint) - pos;

}