[Commit-gnuradio] r8072 - gnuradio/branches/developers/trondeau/ofdm/gnuradio-core/src/lib/general

[trondeau]

Author: trondeau
Date: 2008-03-22 14:26:15 -0600 (Sat, 22 Mar 2008)
New Revision: 8072

Modified:
   
gnuradio/branches/developers/trondeau/ofdm/gnuradio-core/src/lib/general/gr_ofdm_mapper_bcv.cc
Log:
added comments

Modified: 
gnuradio/branches/developers/trondeau/ofdm/gnuradio-core/src/lib/general/gr_ofdm_mapper_bcv.cc
===================================================================
--- 
gnuradio/branches/developers/trondeau/ofdm/gnuradio-core/src/lib/general/gr_ofdm_mapper_bcv.cc
      2008-03-22 20:25:26 UTC (rev 8071)
+++ 
gnuradio/branches/developers/trondeau/ofdm/gnuradio-core/src/lib/general/gr_ofdm_mapper_bcv.cc
      2008-03-22 20:26:15 UTC (rev 8072)
@@ -161,6 +161,7 @@
     }
 
     if(d_nresid > 0) {
+      // take the residual bits, fill out nbits with info from the new byte, 
and put them in the symbol
       d_resid |= (((1 << d_nresid)-1) & d_msgbytes) << (d_nbits - d_nresid);
       bits = d_resid;
 
@@ -174,14 +175,16 @@
       //     bits, d_resid, d_nresid, d_bit_offset);
     }
     else {
-      if((8 - d_bit_offset) >= d_nbits) {
+      if((8 - d_bit_offset) >= d_nbits) {  // test to make sure we can fit 
nbits
+       // take the nbits number of bits at a time from the byte to add to the 
symbol
        bits = ((1 << d_nbits)-1) & (d_msgbytes >> d_bit_offset);
        d_bit_offset += d_nbits;
        
        out[d_subcarrier_map[i]] = d_constellation[bits];
        i++;
       }
-      else {
+      else {  // if we can't fit nbits, store them for the next 
+       // saves d_nresid bits of this message where d_nresid < d_nbits
        unsigned int extra = 8-d_bit_offset;
        d_resid = ((1 << extra)-1) & (d_msgbytes >> d_bit_offset);
        d_bit_offset += extra;