vcs-svn: let deltas use data from preimage

diff --git a/pack-write.c b/pack-write.c
index 9f47cf9961212242bc01082944e83fb54da2a515..a905ca4486754f099a30f90a2fcd22d0c771a070 100644 (file)
--- a/pack-write.c
+++ b/pack-write.c
@@ -253,3 +253,30 @@ char *index_pack_lockfile(int ip_out)
        }
        return NULL;
 }
+
+/*
+ * The per-object header is a pretty dense thing, which is
+ *  - first byte: low four bits are "size", then three bits of "type",
+ *    and the high bit is "size continues".
+ *  - each byte afterwards: low seven bits are size continuation,
+ *    with the high bit being "size continues"
+ */
+int encode_in_pack_object_header(enum object_type type, uintmax_t size, unsigned char *hdr)
+{
+       int n = 1;
+       unsigned char c;
+
+       if (type < OBJ_COMMIT || type > OBJ_REF_DELTA)
+               die("bad type %d", type);
+
+       c = (type << 4) | (size & 15);
+       size >>= 4;
+       while (size) {
+               *hdr++ = c | 0x80;
+               c = size & 0x7f;
+               size >>= 7;
+               n++;
+       }
+       *hdr = c;
+       return n;
+}