Merge pull request #2759 from eisenhauer/comment

Update format comment, add note about endian support
ornladios · Jun 9, 2021 · 1b16bdd · 1b16bdd
2 parents c678e3a + 7f74a08
commit 1b16bdd
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Showing 2 changed files with 22 additions and 6 deletions.
diff --git a/source/adios2/engine/bp5/BP5Engine.h b/source/adios2/engine/bp5/BP5Engine.h
@@ -129,12 +129,14 @@ class BP5Engine
  *number of different "formats" written by any rank.
  *
  *
- *   MetaData file (md.0) contains encoded metadata for each timestep, for each
- *rank BP5 header for "Metadata" (64 bytes) for each timestep: uint64_t
- *TotalSize of this metadata block (including this length) uint64_t[WriterCount]
- *Length of each writer rank's metadata for each rank FFS-encoded metadata block
- *of length corresponding to entry above
- *
+ *   MetaData file (md.0) contains encoded metadata/attribute data
+ *	BP5 header for "Metadata" (64 bytes)
+ *	for each timestep:
+ *		uint64_t  : TotalSize of this metadata block
+ *		uint64_t[WriterCount]  : Length of each rank's metadata
+ *		uint64_t[WriterCount]  : Length of each rank's attribute
+ *		FFS-encoded metadata block of the length above
+ *		FFS-encoded attribute data block of the length above
  *
  *   Data file (data.x) contains a block of data for each timestep, for each
  *rank

diff --git a/source/adios2/toolkit/format/bp5/BP5Deserializer.cpp b/source/adios2/toolkit/format/bp5/BP5Deserializer.cpp
@@ -798,6 +798,20 @@ static int FindOffsetCM(size_t Dims, const size_t *Size, const size_t *Index)
  *  - InData is the input, a slab of the global array
  *  - OutData is the output, to be filled with the selection array.
  */
+
+/*
+ * *******************************
+ *
+ * ExtractSelectionFromPartial*M both need to be extended to work when
+ * the reader and writer have different byte orders.  This involves at
+ * least supporting simple big/little-endian byte reversal, but a true
+ * archival format should also consider mixed and middle-endian
+ * hybrids.  This would require changes to the BP5 header so that the
+ * appropriate transformations could be determined.
+ *
+ * *******************************
+ */
+
 // Row major version
 void BP5Deserializer::ExtractSelectionFromPartialRM(
     int ElementSize, size_t Dims, const size_t *GlobalDims,