/*

 * 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 "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;

}