forked from blender/blender
WIP: uv-simple-select #1
@ -16,13 +16,13 @@
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*
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*
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* The compact nature of storing bools in individual bits has some downsides that have to be kept
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* The compact nature of storing bools in individual bits has some downsides that have to be kept
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* in mind:
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* in mind:
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* - Writing to separate bits in the same byte is not thread-safe. Therefore, an existing vector of
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* - Writing to separate bits in the same int is not thread-safe. Therefore, an existing vector of
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* bool can't easily be replaced with a bit vector, if it is written to from multiple threads.
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* bool can't easily be replaced with a bit vector, if it is written to from multiple threads.
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* Read-only access from multiple threads is fine though.
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* Read-only access from multiple threads is fine though.
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* - Writing individual elements is more expensive when the array is in cache already. That is
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* - Writing individual elements is more expensive when the array is in cache already. That is
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* because changing a bit is always a read-modify-write operation on the byte the bit resides in.
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* because changing a bit is always a read-modify-write operation on the int the bit resides in.
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* - Reading individual elements is more expensive when the array is in cache already. That is
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* - Reading individual elements is more expensive when the array is in cache already. That is
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* because additional bit-wise operations have to be applied after the corresponding byte is
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* because additional bit-wise operations have to be applied after the corresponding int is
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* read.
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* read.
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*
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*
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* Comparison to `std::vector<bool>`:
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* Comparison to `std::vector<bool>`:
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@ -42,18 +42,27 @@
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#include "BLI_memory_utils.hh"
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#include "BLI_memory_utils.hh"
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#include "BLI_span.hh"
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#include "BLI_span.hh"
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namespace blender {
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namespace blender::bits {
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/**
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/**
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* This is a read-only pointer to a specific bit. The value of the bit can be retrieved, but not
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* Using a large integer type is better because then it's easier to process many bits at once.
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* changed.
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*/
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using IntType = uint64_t;
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static constexpr int64_t BitsPerInt = int64_t(sizeof(IntType) * 8);
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static constexpr int64_t BitToIntIndexShift = 3 + (sizeof(IntType) >= 2) + (sizeof(IntType) >= 4) +
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(sizeof(IntType) >= 8);
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static constexpr IntType BitIndexMask = (IntType(1) << BitToIntIndexShift) - 1;
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/**
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* This is a read-only pointer to a specific bit. The value of the bit can be retrieved, but
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* not changed.
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*/
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*/
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class BitRef {
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class BitRef {
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private:
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private:
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/** Points to the exact byte that the bit is in. */
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/** Points to the integer that the bit is in. */
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const uint8_t *byte_ptr_;
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const IntType *ptr_;
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/** All zeros except for a single one at the bit that is referenced. */
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/** All zeros except for a single one at the bit that is referenced. */
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uint8_t mask_;
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IntType mask_;
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friend class MutableBitRef;
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friend class MutableBitRef;
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@ -61,13 +70,13 @@ class BitRef {
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BitRef() = default;
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BitRef() = default;
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/**
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/**
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* Reference a specific bit in a byte array. Note that #byte_ptr does *not* have to point to the
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* Reference a specific bit in an array. Note that #ptr does *not* have to point to the
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* exact byte the bit is in.
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* exact integer the bit is in.
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*/
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*/
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BitRef(const uint8_t *byte_ptr, const int64_t bit_index)
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BitRef(const IntType *ptr, const int64_t bit_index)
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{
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{
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byte_ptr_ = byte_ptr + (bit_index >> 3);
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ptr_ = ptr + (bit_index >> BitToIntIndexShift);
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mask_ = 1 << (bit_index & 7);
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mask_ = IntType(1) << (bit_index & BitIndexMask);
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}
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}
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/**
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/**
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@ -75,9 +84,9 @@ class BitRef {
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*/
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*/
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bool test() const
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bool test() const
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{
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{
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const uint8_t byte = *byte_ptr_;
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const IntType value = *ptr_;
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const uint8_t masked_byte = byte & mask_;
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const IntType masked_value = value & mask_;
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return masked_byte != 0;
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return masked_value != 0;
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}
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}
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operator bool() const
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operator bool() const
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@ -91,22 +100,22 @@ class BitRef {
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*/
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*/
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class MutableBitRef {
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class MutableBitRef {
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private:
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private:
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/** Points to the exact byte that the bit is in. */
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/** Points to the integer that the bit is in. */
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uint8_t *byte_ptr_;
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IntType *ptr_;
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/** All zeros except for a single one at the bit that is referenced. */
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/** All zeros except for a single one at the bit that is referenced. */
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uint8_t mask_;
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IntType mask_;
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public:
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public:
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MutableBitRef() = default;
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MutableBitRef() = default;
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/**
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/**
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* Reference a specific bit in a byte array. Note that #byte_ptr does *not* have to point to the
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* Reference a specific bit in an array. Note that #ptr does *not* have to point to the
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* exact byte the bit is in.
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* exact int the bit is in.
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*/
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*/
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MutableBitRef(uint8_t *byte_ptr, const int64_t bit_index)
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MutableBitRef(IntType *ptr, const int64_t bit_index)
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{
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{
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byte_ptr_ = byte_ptr + (bit_index >> 3);
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ptr_ = ptr + (bit_index >> BitToIntIndexShift);
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mask_ = 1 << uint8_t(bit_index & 7);
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mask_ = IntType(1) << IntType(bit_index & BitIndexMask);
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}
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}
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/**
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/**
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@ -115,7 +124,7 @@ class MutableBitRef {
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operator BitRef() const
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operator BitRef() const
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{
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{
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BitRef bit_ref;
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BitRef bit_ref;
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bit_ref.byte_ptr_ = byte_ptr_;
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bit_ref.ptr_ = ptr_;
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bit_ref.mask_ = mask_;
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bit_ref.mask_ = mask_;
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return bit_ref;
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return bit_ref;
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}
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}
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@ -125,9 +134,9 @@ class MutableBitRef {
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*/
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*/
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bool test() const
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bool test() const
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{
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{
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const uint8_t byte = *byte_ptr_;
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const IntType value = *ptr_;
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const uint8_t masked_byte = byte & mask_;
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const IntType masked_value = value & mask_;
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return masked_byte != 0;
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return masked_value != 0;
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}
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}
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operator bool() const
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operator bool() const
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@ -140,7 +149,7 @@ class MutableBitRef {
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*/
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*/
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void set()
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void set()
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{
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{
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*byte_ptr_ |= mask_;
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*ptr_ |= mask_;
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}
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}
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/**
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/**
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@ -148,7 +157,7 @@ class MutableBitRef {
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*/
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*/
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void reset()
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void reset()
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{
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{
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*byte_ptr_ &= ~mask_;
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*ptr_ &= ~mask_;
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}
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}
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/**
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/**
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@ -177,21 +186,20 @@ template<
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typename Allocator = GuardedAllocator>
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typename Allocator = GuardedAllocator>
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class BitVector {
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class BitVector {
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private:
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private:
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static constexpr int64_t required_bytes_for_bits(const int64_t number_of_bits)
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static constexpr int64_t required_ints_for_bits(const int64_t number_of_bits)
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{
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{
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return (number_of_bits + BitsPerByte - 1) / BitsPerByte;
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return (number_of_bits + BitsPerInt - 1) / BitsPerInt;
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}
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}
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static constexpr int64_t BitsPerByte = 8;
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static constexpr int64_t IntsInInlineBuffer = required_ints_for_bits(InlineBufferCapacity);
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static constexpr int64_t BytesInInlineBuffer = required_bytes_for_bits(InlineBufferCapacity);
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static constexpr int64_t BitsInInlineBuffer = IntsInInlineBuffer * BitsPerInt;
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static constexpr int64_t BitsInInlineBuffer = BytesInInlineBuffer * BitsPerByte;
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static constexpr int64_t AllocationAlignment = alignof(IntType);
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static constexpr int64_t AllocationAlignment = 8;
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/**
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/**
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* Points to the first byte used by the vector. It might point to the memory in the inline
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* Points to the first integer used by the vector. It might point to the memory in the inline
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* buffer.
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* buffer.
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*/
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*/
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uint8_t *data_;
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IntType *data_;
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/** Current size of the vector in bits. */
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/** Current size of the vector in bits. */
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int64_t size_in_bits_;
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int64_t size_in_bits_;
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@ -203,7 +211,7 @@ class BitVector {
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BLI_NO_UNIQUE_ADDRESS Allocator allocator_;
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BLI_NO_UNIQUE_ADDRESS Allocator allocator_;
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/** Contains the bits as long as the vector is small enough. */
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/** Contains the bits as long as the vector is small enough. */
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BLI_NO_UNIQUE_ADDRESS TypedBuffer<uint8_t, BytesInInlineBuffer> inline_buffer_;
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BLI_NO_UNIQUE_ADDRESS TypedBuffer<IntType, IntsInInlineBuffer> inline_buffer_;
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public:
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public:
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BitVector(Allocator allocator = {}) noexcept : allocator_(allocator)
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BitVector(Allocator allocator = {}) noexcept : allocator_(allocator)
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@ -211,7 +219,7 @@ class BitVector {
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data_ = inline_buffer_;
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data_ = inline_buffer_;
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size_in_bits_ = 0;
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size_in_bits_ = 0;
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capacity_in_bits_ = BitsInInlineBuffer;
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capacity_in_bits_ = BitsInInlineBuffer;
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uninitialized_fill_n(data_, BytesInInlineBuffer, uint8_t(0));
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uninitialized_fill_n(data_, IntsInInlineBuffer, IntType(0));
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}
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}
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BitVector(NoExceptConstructor, Allocator allocator = {}) noexcept : BitVector(allocator)
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BitVector(NoExceptConstructor, Allocator allocator = {}) noexcept : BitVector(allocator)
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@ -220,29 +228,29 @@ class BitVector {
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BitVector(const BitVector &other) : BitVector(NoExceptConstructor(), other.allocator_)
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BitVector(const BitVector &other) : BitVector(NoExceptConstructor(), other.allocator_)
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{
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{
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const int64_t bytes_to_copy = other.used_bytes_amount();
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const int64_t ints_to_copy = other.used_ints_amount();
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if (other.size_in_bits_ <= BitsInInlineBuffer) {
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if (other.size_in_bits_ <= BitsInInlineBuffer) {
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/* The data is copied into the owned inline buffer. */
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/* The data is copied into the owned inline buffer. */
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data_ = inline_buffer_;
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data_ = inline_buffer_;
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capacity_in_bits_ = BitsInInlineBuffer;
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capacity_in_bits_ = BitsInInlineBuffer;
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}
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}
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else {
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else {
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/* Allocate a new byte array because the inline buffer is too small. */
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/* Allocate a new array because the inline buffer is too small. */
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data_ = static_cast<uint8_t *>(
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data_ = static_cast<IntType *>(
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allocator_.allocate(bytes_to_copy, AllocationAlignment, __func__));
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allocator_.allocate(ints_to_copy * sizeof(IntType), AllocationAlignment, __func__));
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capacity_in_bits_ = bytes_to_copy * BitsPerByte;
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capacity_in_bits_ = ints_to_copy * BitsPerInt;
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}
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}
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size_in_bits_ = other.size_in_bits_;
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size_in_bits_ = other.size_in_bits_;
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uninitialized_copy_n(other.data_, bytes_to_copy, data_);
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uninitialized_copy_n(other.data_, ints_to_copy, data_);
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}
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}
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BitVector(BitVector &&other) noexcept : BitVector(NoExceptConstructor(), other.allocator_)
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BitVector(BitVector &&other) noexcept : BitVector(NoExceptConstructor(), other.allocator_)
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{
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{
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if (other.is_inline()) {
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if (other.is_inline()) {
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/* Copy the data into the inline buffer. */
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/* Copy the data into the inline buffer. */
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const int64_t bytes_to_copy = other.used_bytes_amount();
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const int64_t ints_to_copy = other.used_ints_amount();
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data_ = inline_buffer_;
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data_ = inline_buffer_;
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uninitialized_copy_n(other.data_, bytes_to_copy, data_);
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uninitialized_copy_n(other.data_, ints_to_copy, data_);
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}
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}
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else {
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else {
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/* Steal the pointer. */
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/* Steal the pointer. */
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@ -305,7 +313,7 @@ class BitVector {
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|
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bool is_empty() const
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bool is_empty() const
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{
|
{
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return this->size() == 0;
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return size_in_bits_ == 0;
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}
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}
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/**
|
/**
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@ -442,20 +450,20 @@ class BitVector {
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*/
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*/
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void fill_range(const IndexRange range, const bool value)
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void fill_range(const IndexRange range, const bool value)
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{
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{
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const AlignedIndexRanges aligned_ranges = split_index_range_by_alignment(range, BitsPerByte);
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const AlignedIndexRanges aligned_ranges = split_index_range_by_alignment(range, BitsPerInt);
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|
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/* Fill first few bits. */
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/* Fill first few bits. */
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for (const int64_t i : aligned_ranges.prefix) {
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for (const int64_t i : aligned_ranges.prefix) {
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(*this)[i].set(value);
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(*this)[i].set(value);
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}
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}
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|
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/* Fill entire bytes at once. */
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/* Fill entire ints at once. */
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const int64_t start_fill_byte_index = aligned_ranges.aligned.start() / BitsPerByte;
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const int64_t start_fill_int_index = aligned_ranges.aligned.start() / BitsPerInt;
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const int64_t bytes_to_fill = aligned_ranges.aligned.size() / BitsPerByte;
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const int64_t ints_to_fill = aligned_ranges.aligned.size() / BitsPerInt;
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const uint8_t fill_value = value ? uint8_t(0xff) : uint8_t(0x00);
|
const IntType fill_value = value ? IntType(-1) : IntType(0);
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initialized_fill_n(data_ + start_fill_byte_index, bytes_to_fill, fill_value);
|
initialized_fill_n(data_ + start_fill_int_index, ints_to_fill, fill_value);
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|
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/* Fill bits in the end that don't cover a full byte. */
|
/* Fill bits in the end that don't cover a full int. */
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for (const int64_t i : aligned_ranges.suffix) {
|
for (const int64_t i : aligned_ranges.suffix) {
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(*this)[i].set(value);
|
(*this)[i].set(value);
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}
|
}
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@ -509,37 +517,35 @@ class BitVector {
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}
|
}
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|
|
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BLI_NOINLINE void realloc_to_at_least(const int64_t min_capacity_in_bits,
|
BLI_NOINLINE void realloc_to_at_least(const int64_t min_capacity_in_bits,
|
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const uint8_t initial_value_for_new_bytes = 0x00)
|
const IntType initial_value_for_new_ints = 0x00)
|
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{
|
{
|
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if (capacity_in_bits_ >= min_capacity_in_bits) {
|
if (capacity_in_bits_ >= min_capacity_in_bits) {
|
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return;
|
return;
|
||||||
}
|
}
|
||||||
|
|
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const int64_t min_capacity_in_bytes = this->required_bytes_for_bits(min_capacity_in_bits);
|
const int64_t min_capacity_in_ints = this->required_ints_for_bits(min_capacity_in_bits);
|
||||||
|
|
||||||
/* At least double the size of the previous allocation. */
|
/* At least double the size of the previous allocation. */
|
||||||
const int64_t min_new_capacity_in_bytes = capacity_in_bits_ * 2;
|
const int64_t min_new_capacity_in_ints = 2 * this->required_ints_for_bits(capacity_in_bits_);
|
||||||
|
|
||||||
const int64_t new_capacity_in_bytes = std::max(min_capacity_in_bytes,
|
const int64_t new_capacity_in_ints = std::max(min_capacity_in_ints, min_new_capacity_in_ints);
|
||||||
min_new_capacity_in_bytes);
|
const int64_t ints_to_copy = this->used_ints_amount();
|
||||||
const int64_t bytes_to_copy = this->used_bytes_amount();
|
|
||||||
|
|
||||||
uint8_t *new_data = static_cast<uint8_t *>(
|
IntType *new_data = static_cast<IntType *>(allocator_.allocate(
|
||||||
allocator_.allocate(new_capacity_in_bytes, AllocationAlignment, __func__));
|
new_capacity_in_ints * sizeof(IntType), AllocationAlignment, __func__));
|
||||||
uninitialized_copy_n(data_, bytes_to_copy, new_data);
|
uninitialized_copy_n(data_, ints_to_copy, new_data);
|
||||||
/* Always initialize new capacity even if it isn't used yet. That's necessary to avoid warnings
|
/* Always initialize new capacity even if it isn't used yet. That's necessary to avoid warnings
|
||||||
* caused by using uninitialized memory. This happens when e.g. setting a clearing a bit in an
|
* caused by using uninitialized memory. This happens when e.g. setting a clearing a bit in an
|
||||||
* uninitialized byte. */
|
* uninitialized int. */
|
||||||
uninitialized_fill_n(new_data + bytes_to_copy,
|
uninitialized_fill_n(
|
||||||
new_capacity_in_bytes - bytes_to_copy,
|
new_data + ints_to_copy, new_capacity_in_ints - ints_to_copy, initial_value_for_new_ints);
|
||||||
uint8_t(initial_value_for_new_bytes));
|
|
||||||
|
|
||||||
if (!this->is_inline()) {
|
if (!this->is_inline()) {
|
||||||
allocator_.deallocate(data_);
|
allocator_.deallocate(data_);
|
||||||
}
|
}
|
||||||
|
|
||||||
data_ = new_data;
|
data_ = new_data;
|
||||||
capacity_in_bits_ = new_capacity_in_bytes * BitsPerByte;
|
capacity_in_bits_ = new_capacity_in_ints * BitsPerInt;
|
||||||
}
|
}
|
||||||
|
|
||||||
bool is_inline() const
|
bool is_inline() const
|
||||||
@ -547,10 +553,16 @@ class BitVector {
|
|||||||
return data_ == inline_buffer_;
|
return data_ == inline_buffer_;
|
||||||
}
|
}
|
||||||
|
|
||||||
int64_t used_bytes_amount() const
|
int64_t used_ints_amount() const
|
||||||
{
|
{
|
||||||
return this->required_bytes_for_bits(size_in_bits_);
|
return this->required_ints_for_bits(size_in_bits_);
|
||||||
}
|
}
|
||||||
};
|
};
|
||||||
|
|
||||||
|
} // namespace blender::bits
|
||||||
|
|
||||||
|
namespace blender {
|
||||||
|
using bits::BitRef;
|
||||||
|
using bits::BitVector;
|
||||||
|
using bits::MutableBitRef;
|
||||||
} // namespace blender
|
} // namespace blender
|
||||||
|
Loading…
Reference in New Issue
Block a user