80 lines
2.1 KiB
C++
80 lines
2.1 KiB
C++
// Copyright 2015-2016 Espressif Systems (Shanghai) PTE LTD
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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#ifndef compressed_enum_table_h
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#define compressed_enum_table_h
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#include <cstdint>
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#include <cassert>
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#include <type_traits>
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template<typename Tenum, size_t Nbits, size_t Nitems>
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class CompressedEnumTable
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{
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public:
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uint32_t* data()
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{
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return mData;
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}
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const uint32_t* data() const
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{
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return mData;
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}
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Tenum get(size_t index) const
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{
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assert(index >= 0 && index < Nitems);
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size_t wordIndex = index / ITEMS_PER_WORD;
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size_t offset = (index % ITEMS_PER_WORD) * Nbits;
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return static_cast<Tenum>((mData[wordIndex] >> offset) & VALUE_MASK);
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}
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void set(size_t index, Tenum val)
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{
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assert(index >= 0 && index < Nitems);
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size_t wordIndex = index / ITEMS_PER_WORD;
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size_t offset = (index % ITEMS_PER_WORD) * Nbits;
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uint32_t v = static_cast<uint32_t>(val) << offset;
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mData[wordIndex] = (mData[wordIndex] & ~(VALUE_MASK << offset)) | v;
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}
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static constexpr size_t getWordIndex(size_t index)
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{
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return index / ITEMS_PER_WORD;
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}
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static constexpr size_t byteSize()
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{
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return WORD_COUNT * 4;
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}
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static constexpr size_t count()
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{
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return Nitems;
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}
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protected:
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static_assert(32 % Nbits == 0, "Nbits must divide 32");
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static const size_t ITEMS_PER_WORD = 32 / Nbits;
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static const size_t WORD_COUNT = ( Nbits * Nitems + 31 ) / 32;
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static const uint32_t VALUE_MASK = (1 << Nbits) - 1;
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uint32_t mData[WORD_COUNT];
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};
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#endif /* compressed_enum_table_h */
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