[Discuss-gnuradio] question about gr_ofdm_sampler.cc

[bin zan]

Hi,
      I just wonder why in gr_ofdm_sampler.cc, the  consume_each for STATE_NO_SIG and STATE_PREAMBLE are different.
consume_each(index - d_fft_length + 1);
consume_each(index-d_fft_length); 

Both suppose to  leave one  fft length, right? 
Can any one explain it?

Thanks,
Bi