blob: f6e083d613a5ce5309bfe319e0e528962e464fb0 [file] [log] [blame]
/*
* Copyright (C) 2017 The Android Open Source Project
*
* 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 <algorithm>
#include "index_bss_mapping.h"
#include "base/bit_utils.h"
#include "base/length_prefixed_array.h"
namespace art {
size_t IndexBssMappingEntry::GetBssOffset(size_t index_bits,
uint32_t index,
size_t slot_size) const {
uint32_t diff = GetIndex(index_bits) - index;
if (diff == 0u) {
return bss_offset;
}
size_t mask_bits = 32u - index_bits;
if (diff > mask_bits) {
return IndexBssMappingLookup::npos;
}
// Shift out the index bits and bits for lower indexes.
// Note that `index_bits + (mask_bits - diff) == 32 - diff`.
uint32_t mask_from_index = index_and_mask >> (32u - diff);
if ((mask_from_index & 1u) != 0u) {
return bss_offset - POPCOUNT(mask_from_index) * slot_size;
} else {
return IndexBssMappingLookup::npos;
}
}
size_t IndexBssMappingLookup::GetBssOffset(const IndexBssMapping* mapping,
uint32_t index,
uint32_t number_of_indexes,
size_t slot_size) {
DCHECK_LT(index, number_of_indexes);
if (mapping == nullptr) {
return npos;
}
size_t index_bits = IndexBssMappingEntry::IndexBits(number_of_indexes);
uint32_t index_mask = IndexBssMappingEntry::IndexMask(index_bits);
auto it = std::partition_point(
mapping->begin(),
mapping->end(),
[=](const struct IndexBssMappingEntry& entry) {
return (entry.index_and_mask & index_mask) < index;
});
if (it == mapping->end()) {
return npos;
}
const IndexBssMappingEntry& entry = *it;
return entry.GetBssOffset(index_bits, index, slot_size);
}
} // namespace art