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// Copyright (c) 2011 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 "content/common/inter_process_time_ticks_converter.h"
#include "base/logging.h"
namespace content {
InterProcessTimeTicksConverter::InterProcessTimeTicksConverter(
const LocalTimeTicks& local_lower_bound,
const LocalTimeTicks& local_upper_bound,
const RemoteTimeTicks& remote_lower_bound,
const RemoteTimeTicks& remote_upper_bound)
: remote_lower_bound_(remote_lower_bound.value_),
remote_upper_bound_(remote_upper_bound.value_) {
int64 target_range = local_upper_bound.value_ - local_lower_bound.value_;
int64 source_range = remote_upper_bound.value_ - remote_lower_bound.value_;
if (source_range <= target_range) {
// We fit! Just shift the midpoints to match.
numerator_ = 1;
denominator_ = 1;
offset_ = ((local_upper_bound.value_ + local_lower_bound.value_) -
(remote_upper_bound.value_ + remote_lower_bound.value_)) / 2;
return;
}
// Set up scaling factors, and then deduce shift.
numerator_ = target_range;
denominator_ = source_range;
// Find out what we need to shift by to make this really work.
offset_ = local_lower_bound.value_ - Convert(remote_lower_bound.value_);
DCHECK_GE(local_upper_bound.value_, Convert(remote_upper_bound.value_));
}
LocalTimeTicks InterProcessTimeTicksConverter::ToLocalTimeTicks(
const RemoteTimeTicks& remote_ms) {
DCHECK_LE(remote_lower_bound_, remote_ms.value_);
DCHECK_GE(remote_upper_bound_, remote_ms.value_);
RemoteTimeDelta remote_delta = remote_ms - remote_lower_bound_;
return LocalTimeTicks(remote_lower_bound_ + offset_ +
ToLocalTimeDelta(remote_delta).value_);
}
LocalTimeDelta InterProcessTimeTicksConverter::ToLocalTimeDelta(
const RemoteTimeDelta& remote_delta) {
DCHECK_GE(remote_upper_bound_, remote_lower_bound_ + remote_delta.value_);
return LocalTimeDelta(Convert(remote_delta.value_));
}
int64 InterProcessTimeTicksConverter::Convert(int64 value) {
if (value <= 0) {
return value;
}
return numerator_ * value / denominator_;
}
} // namespace content
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