[PATCH/RFC v2 5/9] pack-objects: note about in_pack_header_size

Object header in a pack is packed really tight (see
pack-format.txt). Even with 8 bytes length, we need 9-10 bytes most,
plus a hash (20 bytes). Which means this field only needs to store a
number as big as 32 (5 bits).

This is trickier to pack tight though since a new hash algorithm is
coming, the number of bits needed may quickly increase. So leave it
for now.

Signed-off-by: Nguyễn Thái Ngọc Duy <redacted>
---
 pack-objects.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/pack-objects.h b/pack-objects.h
index 2050a05a0b..fb2a3c8f48 100644
--- a/pack-objects.h
+++ b/pack-objects.h

@@ -32,7 +32,7 @@ struct object_entry {
 	unsigned long z_delta_size;	/* delta data size (compressed) */
 	uint32_t hash;			/* name hint hash */
 	unsigned int in_pack_pos;
-	unsigned char in_pack_header_size;
+	unsigned char in_pack_header_size; /* note: spare bits available! */
 	unsigned type:TYPE_BITS;
 	unsigned in_pack_type:TYPE_BITS; /* could be delta */
 	unsigned preferred_base:1; /*

-- 
2.16.1.435.g8f24da2e1a