kiszk commented on code in PR #48215:
URL: https://github.com/apache/arrow/pull/48215#discussion_r3425968191
##########
cpp/src/parquet/arrow/reader_internal.cc:
##########
@@ -851,7 +851,41 @@ Status TransferHalfFloat(RecordReader* reader, MemoryPool*
pool,
std::shared_ptr<ChunkedArray> chunked_array;
RETURN_NOT_OK(
TransferBinary(reader, pool, field->WithType(binary_type),
&chunked_array));
+#if ARROW_LITTLE_ENDIAN
ARROW_ASSIGN_OR_RAISE(*out, chunked_array->View(field->type()));
+#else
+ // Convert little-endian bytes from Parquet to native-endian HalfFloat
+ std::vector<std::shared_ptr<::arrow::Array>> out_chunks;
+ out_chunks.reserve(chunked_array->num_chunks());
+
+ for (const auto& chunk : chunked_array->chunks()) {
+ auto fsb = std::static_pointer_cast<::arrow::FixedSizeBinaryArray>(chunk);
+ const int64_t n = fsb->length();
+
+ // Allocate buffer for native-endian uint16 values
+ ARROW_ASSIGN_OR_RAISE(auto data_buf,
+ ::arrow::AllocateBuffer(n * sizeof(uint16_t), pool));
+ auto* out16 = reinterpret_cast<uint16_t*>(data_buf->mutable_data());
+
+ // Copy and convert from little-endian (Parquet spec) to native-endian
+ for (int64_t i = 0; i < n; ++i) {
Review Comment:
Can we make it simpler w/o `memcpy()` like?
```
for (int64_t i = 0; i < n; ++i) {
// FromLittleEndian handles the load + byte-swap; .bits() gives the
// native-endian uint16 that Arrow's HalfFloatArray expects.
out16[i] =
::arrow::util::Float16::FromLittleEndian(fsb.GetValue(i)).bits();
}
```
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