1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
2 // Use of this source code is governed by a BSD-style license that can be
3 // found in the LICENSE file.
5 #include "sync/internal_api/public/base/node_ordinal.h"
11 NodeOrdinal Int64ToNodeOrdinal(int64 x) {
12 uint64 y = static_cast<uint64>(x);
13 y ^= 0x8000000000000000ULL;
14 std::string bytes(NodeOrdinal::kMinLength, '\x00');
16 // 0 is a special case since |bytes| must not be all zeros.
17 bytes.push_back('\x80');
19 for (int i = 7; i >= 0; --i) {
20 bytes[i] = static_cast<uint8>(y);
24 NodeOrdinal ordinal(bytes);
25 DCHECK(ordinal.IsValid());
29 int64 NodeOrdinalToInt64(const NodeOrdinal& ordinal) {
31 const std::string& s = ordinal.ToInternalValue();
32 size_t l = NodeOrdinal::kMinLength;
37 for (size_t i = 0; i < l; ++i) {
38 const uint8 byte = s[l - i - 1];
39 y |= static_cast<uint64>(byte) << (i * 8);
41 y ^= 0x8000000000000000ULL;
42 // This is technically implementation-defined if y > INT64_MAX, so
43 // we're assuming that we're on a twos-complement machine.
44 return static_cast<int64>(y);