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/*
* Copyright (c) 2020 Samsung Electronics Co., Ltd. All Rights Reserved
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include "IntervalSet.h"
#include <cassert>
#include <stdexcept>
namespace kuma
{
namespace details
{
IntervalSet::IntervalSet(uint32_t len)
{
// Update _content
_content[len] = len;
}
void IntervalSet::insert(const IntervalMask &m)
{
auto s = m.s;
auto e = m.e;
assert(s <= e);
if (s == e)
{
// Empty region, nothing to do
return;
}
// lower_bound() returns an iterator to the first element not less than the given key
auto lb = _content.lower_bound(s);
// NOTE 1. "lower_bound" ensures "prev_s < s <= curr_e"
// NOTE 2. "e" points to somewhere after "s"
auto curr_s = lb->first - lb->second;
auto curr_e = lb->first;
if (curr_s < s)
{
// Split the current interval
_content[s] = s - curr_s;
// NOTE The invariant over "_content" is temporarily broken here.
}
if (e < curr_e)
{
// Adjust the current interval
_content[curr_e] = curr_e - e;
}
else
{
// Remove the current interval
_content.erase(curr_e);
// Check the next interval (e > curr_e)
//
// TODO Remove this recursive call (to prevent stack overflow issue)
insert(mask(curr_e, e));
}
}
uint32_t IntervalSet::firstfit(uint32_t len) const
{
for (auto it = _content.begin(); it != _content.end(); ++it)
{
if (it->second >= len)
{
// Got it! This interval is larger than "len".
return it->first - it->second;
}
}
throw std::runtime_error{"infeasible"};
}
} // namespace details
} // namespace kuma
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