varint.c

   1 #include "git-compat-util.h"
   2 #include "varint.h"
   3
   4 uintmax_t decode_varint(const unsigned char **bufp)
   5 {
   6         const unsigned char *buf = *bufp;
   7         unsigned char c = *buf++;
   8         uintmax_t val = c & 127;
   9         while (c & 128) {
  10                 val += 1;
  11                 if (!val || MSB(val, 7))
  12                         return 0; /* overflow */
  13                 c = *buf++;
  14                 val = (val << 7) + (c & 127);
  15         }
  16         *bufp = buf;
  17         return val;
  18 }
  19
  20 int encode_varint(uintmax_t value, unsigned char *buf)
  21 {
  22         unsigned char varint[16];
  23         unsigned pos = sizeof(varint) - 1;
  24         varint[pos] = value & 127;
  25         while (value >>= 7)
  26                 varint[--pos] = 128 | (--value & 127);
  27         if (buf)
  28                 memcpy(buf, varint + pos, sizeof(varint) - pos);
  29         return sizeof(varint) - pos;
  30 }