diff options
| author | Tom Rondeau <tom@trondeau.com> | 2014-05-17 19:23:44 -0400 |
|---|---|---|
| committer | Tom Rondeau <tom@trondeau.com> | 2014-05-17 19:23:44 -0400 |
| commit | 91b5f380b6c511624064f1b64ae3ebfd710d7272 (patch) | |
| tree | 5c157b11cebf25e110d26f8829287f0b97fb0bfd /gr-fec/lib/cc_decoder_impl.cc | |
| parent | 3245fde378417687db10f7cdeb274c9fa126d4e8 (diff) | |
fec: wip: adding concept of padding for CC encoder/decoder.
When using terminated mode, the CC encoder adds K-1 bits to the output, which doesn't fit a full byte and will throw off the book-keeping in PDU or tagged mode. Padding to fill a byte tells both encoder and decoder to handle the extra bits.
Diffstat (limited to 'gr-fec/lib/cc_decoder_impl.cc')
| -rw-r--r-- | gr-fec/lib/cc_decoder_impl.cc | 29 |
1 files changed, 19 insertions, 10 deletions
diff --git a/gr-fec/lib/cc_decoder_impl.cc b/gr-fec/lib/cc_decoder_impl.cc index 6b7daaf4b2..6739f7bf3d 100644 --- a/gr-fec/lib/cc_decoder_impl.cc +++ b/gr-fec/lib/cc_decoder_impl.cc @@ -40,23 +40,24 @@ namespace gr { cc_decoder::make(int frame_size, int k, int rate, std::vector<int> polys, int start_state, int end_state, - cc_mode_t mode) + cc_mode_t mode, bool padded) { return generic_decoder::sptr (new cc_decoder_impl(frame_size, k, rate, polys, - start_state, end_state, mode)); + start_state, end_state, mode, padded)); } cc_decoder_impl::cc_decoder_impl(int frame_size, int k, int rate, std::vector<int> polys, int start_state, int end_state, - cc_mode_t mode) + cc_mode_t mode, bool padded) : generic_decoder("cc_decoder"), d_k(k), d_rate(rate), d_partial_rate(rate), d_polys(polys), d_mode(mode), + d_padding(0), d_start_state_chaining(start_state), d_start_state_nonchaining(start_state), d_end_state_nonchaining(end_state) @@ -65,7 +66,12 @@ namespace gr { // based on this value. d_max_frame_size = frame_size; d_frame_size = frame_size; - //set_frame_size(frame_size); + + // set up a padding factor. If padding, the encoded frame was exteded + // by this many bits to fit into a full byte. + if(padded && (mode == CC_TERMINATED)) { + d_padding = static_cast<int>(8.0f*ceilf(d_rate*(d_k-1)/8.0f) - (d_rate*(d_k-1))); + } d_vp = new struct v; @@ -170,7 +176,7 @@ namespace gr { cc_decoder_impl::get_input_size() { if(d_mode == CC_TERMINATED) { - return d_rate * (d_frame_size + d_k - 1); + return d_rate * (d_frame_size + d_k - 1) + d_padding; } else { return d_rate * d_frame_size; @@ -365,7 +371,6 @@ namespace gr { d += tailsize * d_decision_t_size ; /* Look past tail */ int retval; int dif = tailsize - (d_k - 1); - //printf("break, %d, %d\n", dif, (nbits+dif)%d_frame_size); decision_t dec; while(nbits-- > d_frame_size - (d_k - 1)) { int k; @@ -373,8 +378,6 @@ namespace gr { k = (dec.w[(endstate>>d_ADDSHIFT)/32] >> ((endstate>>d_ADDSHIFT)%32)) & 1; endstate = (endstate >> 1) | (k << (d_k-2+d_ADDSHIFT)); - //data[((nbits+dif)%nbits)>>3] = endstate>>d_SUBSHIFT; - //printf("%d, %d\n", k, (nbits+dif)%d_frame_size); data[((nbits+dif)%d_frame_size)] = k; retval = endstate; @@ -400,7 +403,7 @@ namespace gr { { bool ret = true; if(frame_size > d_max_frame_size) { - GR_LOG_INFO(d_logger, boost::format("tried to set frame to %1%; max possible is %2%") \ + GR_LOG_INFO(d_logger, boost::format("cc_decoder: tried to set frame to %1%; max possible is %2%") \ % frame_size % d_max_frame_size); frame_size = d_max_frame_size; ret = false; @@ -412,7 +415,7 @@ namespace gr { case(CC_TAILBITING): d_veclen = d_frame_size + (6 * (d_k - 1)); if(d_veclen * d_rate > d_managed_in_size) { - throw std::runtime_error("attempt to resize beyond d_managed_in buffer size!\n"); + throw std::runtime_error("cc_decoder: attempt to resize beyond d_managed_in buffer size!\n"); } break; @@ -421,7 +424,13 @@ namespace gr { break; case(CC_STREAMING): + d_veclen = d_frame_size + d_k - 1; + break; + case(CC_TERMINATED): + // If the input is being padded out to a byte, we know the + // real frame size is without the padding. + d_frame_size -= d_padding * d_rate; d_veclen = d_frame_size + d_k - 1; break; |