paleolimbot commented on code in PR #214:
URL: https://github.com/apache/arrow-nanoarrow/pull/214#discussion_r1223791275
##########
extensions/nanoarrow_ipc/src/nanoarrow/nanoarrow_ipc_decoder.c:
##########
@@ -1297,6 +1299,143 @@ static struct ArrowIpcBufferFactory
ArrowIpcBufferFactoryFromShared(
return out;
}
+// Just for the purposes of endian-swapping (not data access)
+struct ArrowIpcDecimal128 {
+ uint64_t words[2];
+};
+
+struct ArrowIpcDecimal256 {
+ uint64_t words[4];
+};
+
+struct ArrowIpcMonthsDays {
+ uint32_t months;
+ uint32_t days;
+};
+
+struct ArrowIpcIntervalMonthDayNano {
+ union {
+ uint64_t force_align_uint64;
+ struct ArrowIpcMonthsDays months_days;
+ };
+ uint64_t ns;
+};
+
+static int ArrowIpcDecoderSwapEndian(struct ArrowIpcBufferSource* src,
+ struct ArrowBufferView* out_view,
+ struct ArrowBuffer* dst, struct
ArrowError* error) {
+ // Some buffer data types don't need any endian swapping
+ switch (src->data_type) {
+ case NANOARROW_TYPE_BOOL:
+ case NANOARROW_TYPE_INT8:
+ case NANOARROW_TYPE_UINT8:
+ case NANOARROW_TYPE_STRING:
+ case NANOARROW_TYPE_BINARY:
+ return NANOARROW_OK;
+ default:
+ break;
+ }
+
+ // Make sure dst is not a shared buffer that we can't modify
+ struct ArrowBuffer tmp;
+ ArrowBufferInit(&tmp);
+
+ if (dst->allocator.private_data != NULL) {
+ ArrowBufferMove(dst, &tmp);
+ ArrowBufferInit(dst);
+ }
+
+ if (dst->size_bytes == 0) {
+ NANOARROW_RETURN_NOT_OK(ArrowBufferReserve(dst, out_view->size_bytes));
+ dst->size_bytes = out_view->size_bytes;
+ }
+
+ switch (src->data_type) {
+ case NANOARROW_TYPE_DECIMAL128: {
+ struct ArrowIpcDecimal128* ptr_src =
+ (struct ArrowIpcDecimal128*)out_view->data.data;
+ struct ArrowIpcDecimal128* ptr = (struct ArrowIpcDecimal128*)dst->data;
+ uint64_t words[2];
+ for (int64_t i = 0; i < (dst->size_bytes / 16); i++) {
+ words[0] = bswap64(ptr_src[i].words[0]);
+ words[1] = bswap64(ptr_src[i].words[1]);
+ ptr[i].words[0] = words[1];
+ ptr[i].words[1] = words[0];
+ }
Review Comment:
I updated this to not add even more types that we reinterpret cast
to...there are a number of places that (perhaps inadvisably) cast to `int64_t*`
or `uint64_t*`, but adding more seems like a bad idea for marginally better
readability.
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