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// Copyright 2014 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.
#ifndef MEDIA_CAST_COMMON_MOD_UTIL_H_
#define MEDIA_CAST_COMMON_MOD_UTIL_H_
#include <map>
#include "base/logging.h"
namespace media {
namespace cast {
// MAP is a map<uint??, ...> where the unsigned integer is
// assumed to wrap around, but only a small range is used at a time.
// Return the oldest entry in the map.
template<class MAP>
typename MAP::iterator ModMapOldest(MAP* map) {
typename MAP::iterator ret = map->begin();
if (ret != map->end()) {
typename MAP::key_type lower_quarter = 0;
lower_quarter--;
lower_quarter >>= 1;
if (ret->first < lower_quarter) {
typename MAP::iterator tmp = map->upper_bound(lower_quarter * 3);
if (tmp != map->end())
ret = tmp;
}
}
return ret;
}
// MAP is a map<uint??, ...> where the unsigned integer is
// assumed to wrap around, but only a small range is used at a time.
// Returns the previous entry in the map.
template<class MAP>
typename MAP::iterator ModMapPrevious(MAP* map, typename MAP::iterator i) {
DCHECK(!map->empty());
typename MAP::iterator ret = i;
if (i == map->begin()) {
ret = map->end();
}
ret--;
if (i == ret)
return map->end();
if ((i->first - ret->first) > ((typename MAP::key_type(0) - 1)) >> 1)
return map->end();
return ret;
}
} // namespace cast
} // namespace media
#endif
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