compiler/blob: Allow for fixed-size blobs with a NULL data pointer

These can be used to easily count up the number of bytes that will be
required by "writing" it into the NULL blob.

Reviewed-by: Nicolai Hähnle <[email protected]>
Reviewed-by: Jordan Justen <[email protected]>

1 files changed, 4 insertions, 0 deletions

diff --git a/src/compiler/blob.h b/src/compiler/blob.h
index e23e392eedd..ec80b78284c 100644
--- a/src/compiler/blob.h
+++ b/src/compiler/blob.h
@@ -96,6 +96,10 @@ blob_init(struct blob *blob);
  * A fixed-size blob has a fixed block of data that will not be freed on
  * blob_finish and will never be grown.  If we hit the end, we simply start
  * returning false from the write functions.
+ *
+ * If a fixed-size blob has a NULL data pointer then the data is written but
+ * it otherwise operates normally.  This can be used to determine the size
+ * that will be required to write a given data structure.
  */
 void
 blob_init_fixed(struct blob *blob, void *data, size_t size);