1 files changed, 34 insertions, 0 deletions
diff --git a/delta.h b/delta.h
new file mode 100644
index 0000000000..31d1820f80
--- /dev/null
+++ b/delta.h
@@ -0,0 +1,34 @@
+#ifndef DELTA_H
+#define DELTA_H
+
+/* handling of delta buffers */
+extern void *diff_delta(void *from_buf, unsigned long from_size,
+			void *to_buf, unsigned long to_size,
+		        unsigned long *delta_size, unsigned long max_size);
+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 = *data++;
+	unsigned long size = cmd & ~0x80;
+	int i = 7;
+	while (cmd & 0x80) {
+		cmd = *data++;
+		size |= (cmd & ~0x80) << i;
+		i += 7;
+	}
+	*datap = data;
+	return size;
+}
+
+#endif