delta.h

   1 #ifndef DELTA_H
   2 #define DELTA_H
   3
   4 /* handling of delta buffers */
   5 extern void *diff_delta(void *from_buf, unsigned long from_size,
   6                         void *to_buf, unsigned long to_size,
   7                         unsigned long *delta_size, unsigned long max_size);
   8 extern void *patch_delta(void *src_buf, unsigned long src_size,
   9                          void *delta_buf, unsigned long delta_size,
  10                          unsigned long *dst_size);
  11
  12 /* the smallest possible delta size is 4 bytes */
  13 #define DELTA_SIZE_MIN  4
  14
  15 /*
  16  * This must be called twice on the delta data buffer, first to get the
  17  * expected reference buffer size, and again to get the result buffer size.
  18  */
  19 static inline unsigned long get_delta_hdr_size(const unsigned char **datap)
  20 {
  21         const unsigned char *data = *datap;
  22         unsigned char cmd = *data++;
  23         unsigned long size = cmd & ~0x80;
  24         int i = 7;
  25         while (cmd & 0x80) {
  26                 cmd = *data++;
  27                 size |= (cmd & ~0x80) << i;
  28                 i += 7;
  29         }
  30         *datap = data;
  31         return size;
  32 }
  33
  34 #endif