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[git.git] / delta.h

diff --git a/delta.h b/delta.h
index e073dff..31d1820 100644 (file)
--- a/delta.h
+++ b/delta.h
@@ -1,6 +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 *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