Added Packing Heursitics IRC writeup.

diff --git a/delta.h b/delta.h
index bc3a220179cefd0af169ab4f2e6aeeb5675f900a..a15350dabcd497d4cb21261721706eca072de034 100644 (file)
--- a/delta.h
+++ b/delta.h
@@ -9,4 +9,26 @@ extern void *patch_delta(void *src_buf, unsigned long src_size,
                         void *delta_buf, unsigned long delta_size,
                         unsigned long *dst_size);
 
+/* the smallest possible delta size is 4 bytes */
+#define DELTA_SIZE_MIN 4
+
+/*
+ * This must be called twice on the delta data buffer, first to get the
+ * expected reference buffer size, and again to get the result buffer size.
+ */
+static inline unsigned long get_delta_hdr_size(const unsigned char **datap)
+{
+       const unsigned char *data = *datap;
+       unsigned char cmd;
+       unsigned long size = 0;
+       int i = 0;
+       do {
+               cmd = *data++;
+               size |= (cmd & ~0x80) << i;
+               i += 7;
+       } while (cmd & 0x80);
+       *datap = data;
+       return size;
+}
+
 #endif