Optimizing variable-length encoding

I've got a case where I need to compress a lot of often small values. Thus I compress them with a variable-length byte encoding (ULEB128, to be specific):

size_t
compress_unsigned_int(unsigned int n, char* data)
{
  size_t size = 0;
  while (n  > 127)
  {
    ++size;
    *data++ = (n & 127)|128;
    n >>= 7;
  }
  *data++ = n;
  return ++size;
}

Is there a more efficient way to do this (maybe using SSE)?

Edit: After this compression, the result is stored into data, taking size bytes. Then, the compression function is called on the next unsigned int.

If your unsigned int values are limited to a specific range - say, 32 bits - you can unroll the loop:

size_t
compress_unsigned_int(unsigned int n, char* data)
{
  size_t size;

  if (n < 0x00000080U) {
    size = 1;
    goto b1;
  }
  if (n < 0x00004000U) {
    size = 2;
    goto b2;
  }
  if (n < 0x00200000U) {
    size = 3;
    goto b3;
  }
  if (n < 0x10000000U) {
    size = 4;
    goto b4;
  }
  size = 5;

  *data++ = (n & 0x7f) | 0x80;
  n >>= 7;
b4:
  *data++ = (n & 0x7f) | 0x80;
  n >>= 7;
b3:
  *data++ = (n & 0x7f) | 0x80;
  n >>= 7;
b2:
  *data++ = (n & 0x7f) | 0x80;
  n >>= 7;
b1:
  *data = n;
  return size;
}