+#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;
+ unsigned long size = 0;
+ int i = 0;
+ do {
+ cmd = *data++;
+ size |= (cmd & ~0x80) << i;
+ i += 7;
+ } while (cmd & 0x80);
+ *datap = data;
+ return size;
+}
+
+#endif