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// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "sync/internal_api/public/base/node_ordinal.h"
#include <stddef.h>
#include <stdint.h>
#include <algorithm>
#include <string>
namespace syncer {
NodeOrdinal Int64ToNodeOrdinal(int64_t x) {
uint64_t y = static_cast<uint64_t>(x);
y ^= 0x8000000000000000ULL;
std::string bytes(NodeOrdinal::kMinLength, '\x00');
if (y == 0) {
// 0 is a special case since |bytes| must not be all zeros.
bytes.push_back('\x80');
} else {
for (int i = 7; i >= 0; --i) {
bytes[i] = static_cast<uint8_t>(y);
y >>= 8;
}
}
NodeOrdinal ordinal(bytes);
DCHECK(ordinal.IsValid());
return ordinal;
}
int64_t NodeOrdinalToInt64(const NodeOrdinal& ordinal) {
uint64_t y = 0;
const std::string& s = ordinal.ToInternalValue();
size_t l = NodeOrdinal::kMinLength;
if (s.length() < l) {
NOTREACHED();
l = s.length();
}
for (size_t i = 0; i < l; ++i) {
const uint8_t byte = s[l - i - 1];
y |= static_cast<uint64_t>(byte) << (i * 8);
}
y ^= 0x8000000000000000ULL;
// This is technically implementation-defined if y > INT64_MAX, so
// we're assuming that we're on a twos-complement machine.
return static_cast<int64_t>(y);
}
} // namespace syncer
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