rbsp_read_bits
ret = rbsp_read_bits(rbsp, leading_zero_bits, &tmp);
.rbsp_bits = rbsp_read_bits,
static int rbsp_read_bits(struct rbsp *rbsp, int n, unsigned int *value);
rbsp_read_bits(rbsp, 8, &tmp);
ret = rbsp_read_bits(rbsp, leading_zero_bits, &tmp);