[GitHub] [arrow] jorgecarleitao commented on a change in pull request #8262: ARROW-10040: [Rust] Iterate over and combine boolean buffers with arbitrary offsets

[GitBox <gi...@apache.org>]

jorgecarleitao commented on a change in pull request #8262:
URL: https://github.com/apache/arrow/pull/8262#discussion_r501772813



##########
File path: rust/arrow/src/buffer.rs
##########
@@ -369,120 +394,171 @@ where
     result.freeze()
 }
 
+/// Apply a bitwise operation `op` to two inputs and return the result as a Buffer.
+/// The inputs are treated as bitmaps, meaning that offsets and length are specified in number of bits.
 fn bitwise_bin_op_helper<F>(
     left: &Buffer,
-    left_offset: usize,
+    left_offset_in_bits: usize,
     right: &Buffer,
-    right_offset: usize,
-    len: usize,
+    right_offset_in_bits: usize,
+    len_in_bits: usize,
     op: F,
 ) -> Buffer
 where
-    F: Fn(u8, u8) -> u8,
+    F: Fn(u64, u64) -> u64,
 {
-    let mut result = MutableBuffer::new(len).with_bitset(len, false);
+    // reserve capacity and set length so we can get a typed view of u64 chunks
+    let mut result =
+        MutableBuffer::new(ceil(len_in_bits, 8)).with_bitset(len_in_bits / 64 * 8, false);
 
-    result
-        .data_mut()
-        .iter_mut()
-        .zip(
-            left.data()[left_offset..]
-                .iter()
-                .zip(right.data()[right_offset..].iter()),
-        )
+    let left_chunks = left.bit_chunks(left_offset_in_bits, len_in_bits);
+    let right_chunks = right.bit_chunks(right_offset_in_bits, len_in_bits);
+    let result_chunks = result.typed_data_mut::<u64>().iter_mut();
+
+    result_chunks
+        .zip(left_chunks.iter().zip(right_chunks.iter()))

Review comment:
       Out of curiosity, which toolkit or procedure do you guys use for looking at the assembly? I am curious (amazed) how you end up on that level of detail!




----------------------------------------------------------------
This is an automated message from the Apache Git Service.
To respond to the message, please log on to GitHub and use the
URL above to go to the specific comment.

For queries about this service, please contact Infrastructure at:
users@infra.apache.org