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