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110 lines
2.6 KiB
110 lines
2.6 KiB
/**
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* Copyright 2012 Facebook
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* @author Tudor Bosman (tudorb@fb.com)
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*/
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#ifndef THRIFT_LIB_CPP_PROTOCOL_NEUTRONIUM_UTILS_H_
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#define THRIFT_LIB_CPP_PROTOCOL_NEUTRONIUM_UTILS_H_
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#include <cstddef>
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#include <cstdint>
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#include <cassert>
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#include <algorithm>
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namespace apache {
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namespace thrift {
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namespace protocol {
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namespace neutronium {
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// Helper functions for using an array of uint8_t values as a bitset
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// byte index
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constexpr inline size_t byteIndex(size_t bit) {
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return bit / 8;
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}
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// offset within byte
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constexpr inline size_t bitOffset(size_t bit) {
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return bit % 8;
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}
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// number of bytes needed to represent bitCount bits (round up)
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constexpr inline size_t byteCount(size_t bitCount) {
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return bitCount / 8 + (bitCount % 8 != 0);
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}
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// set bit
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inline void setBit(uint8_t* p, size_t bit) {
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p[byteIndex(bit)] |= (1 << bitOffset(bit));
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}
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inline void setBits(uint8_t* p, size_t bit, size_t count, uint32_t value) {
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assert(value < (1 << count));
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while (count) {
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size_t index = byteIndex(bit);
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size_t offset = bitOffset(bit);
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size_t countInThisByte = std::min(count, 8 - offset);
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// Extract "countInThisByte" bits from value
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uint8_t mask = (1 << countInThisByte) - 1;
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uint8_t v = value & mask;
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// Wipe out these bits, then set them to the new value
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p[index] = (p[index] & ~(mask << offset)) | (v << offset);
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value >>= countInThisByte;
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bit += countInThisByte;
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count -= countInThisByte;
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}
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}
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inline uint32_t getBits(uint8_t* p, size_t bit, size_t count) {
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uint32_t value = 0;
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size_t shift = 0;
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while (count) {
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size_t index = byteIndex(bit);
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size_t offset = bitOffset(bit);
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size_t countInThisByte = std::min(count, 8 - offset);
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uint8_t mask = (1 << countInThisByte) - 1;
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uint8_t v = (p[index] & (mask << offset)) >> offset;
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value |= (v << shift);
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shift += countInThisByte;
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bit += countInThisByte;
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count -= countInThisByte;
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}
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return value;
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}
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// clear bit
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inline void clearBit(uint8_t* p, size_t bit) {
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p[byteIndex(bit)] &= ~(1 << bitOffset(bit));
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}
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// test bit
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inline bool testBit(const uint8_t* p, size_t bit) {
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return p[byteIndex(bit)] & (1 << bitOffset(bit));
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}
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// Overloads for vector<uint8_t>, array<uint8_t>, or anything else that has
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// a working operator[]
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template <class T>
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inline void setBit(T& p, size_t bit) {
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setBit(&p[0], bit);
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}
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template <class T>
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inline void clearBit(T& p, size_t bit) {
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clearBit(&p[0], bit);
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}
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template <class T>
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inline bool testBit(const T& p, size_t bit) {
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return testBit(&p[0], bit);
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}
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} // namespace neutronium
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} // namespace protocol
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} // namespace thrift
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} // namespace apache
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#endif /* THRIFT_LIB_CPP_PROTOCOL_NEUTRONIUM_UTILS_H_ */
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