kiszk commented on a change in pull request #7135:
URL: https://github.com/apache/arrow/pull/7135#discussion_r422764992
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File path: cpp/src/arrow/util/bit_util.cc
##########
@@ -273,28 +274,115 @@ void AlignedBitmapOp(const uint8_t* left, int64_t
left_offset, const uint8_t* ri
}
}
-template <typename Op>
+template <template <typename> class BitOp, typename LogicalOp>
void UnalignedBitmapOp(const uint8_t* left, int64_t left_offset, const
uint8_t* right,
int64_t right_offset, uint8_t* out, int64_t out_offset,
int64_t length) {
- Op op;
- auto left_reader = internal::BitmapReader(left, left_offset, length);
- auto right_reader = internal::BitmapReader(right, right_offset, length);
- auto writer = internal::BitmapWriter(out, out_offset, length);
- for (int64_t i = 0; i < length; ++i) {
- if (op(left_reader.IsSet(), right_reader.IsSet())) {
- writer.Set();
- } else {
- writer.Clear();
+ using Word = uint64_t;
+
+ left += left_offset / 8;
+ right += right_offset / 8;
+ out += out_offset / 8;
+
+ left_offset %= 8;
+ right_offset %= 8;
+ out_offset %= 8;
+
+ const int64_t min_offset = std::min({left_offset, right_offset, out_offset});
+ const int64_t min_nbytes = BitUtil::BytesForBits(length + min_offset);
+ int64_t nwords = min_nbytes / sizeof(Word);
+
+ // process in words, we may touch two words in each iteration
+ if (nwords > 1) {
+ BitOp<Word> op;
+ constexpr int64_t bits_per_word = sizeof(Word) * 8;
+ const Word out_mask = (1U << out_offset) - 1;
+
+ length -= (nwords - 1) * bits_per_word;
+ Word left_word0 = util::SafeLoadAs<Word>(left);
+ Word right_word0 = util::SafeLoadAs<Word>(right);
+ Word out_word0 = util::SafeLoadAs<Word>(out);
+
+ do {
Review comment:
Thank you very much for your fix.
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