mirror of https://github.com/lwvmobile/dsd-fme.git
M17 - Tweaks to LSF Frame Decoding;
This commit is contained in:
lwvmobile
parent
7d8a081e3f
commit
bceac916fe
297
src/m17.c
297
src/m17.c
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@ -707,41 +707,29 @@ void processM17STR(dsd_opts * opts, dsd_state * state)
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} //end processM17STR
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//original version using nxdn convolutional decoder
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void processM17LSF(dsd_opts * opts, dsd_state * state)
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{
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//WIP: Switch to libM17 Viterbi Decoder for better performance
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//Not yet working on actual signal, but debug version works
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//most likely frame sync / demodulation related issue
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//NOTE: Viterbi Decoder seems to respnd better
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//when the 112-bit nonce value isn't all zeroes
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//TODO: Work on implementing a symbol buffer of some sort
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//when the preamble starts?
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//NOTE: Works now with decisions based on previous bit, but still
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//not quite as good as it needs to be, need better decision making on the punctured bit
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int i, j, k, x;
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uint8_t dbuf[184]; //384-bit (192 symbol) frame - 16-bit (8 symbol) sync pattern (184 dibits)
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uint8_t dbuf[184]; //384-bit frame - 16-bit (8 symbol) sync pattern (184 dibits)
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uint8_t m17_rnd_bits[368]; //368 bits that are still scrambled (randomized)
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uint8_t m17_int_bits[368]; //368 bits that are still interleaved
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uint8_t m17_rnd_bits[368]; //368 bits that are still scrambled
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uint16_t m17_bits[368]; //368 bits that have been de-interleaved and de-scrambled
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uint16_t m17_depunc[488]; //488 weighted byte representation of bits after depuncturing
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uint8_t lsf_bytes[31];
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uint8_t lsf_packed[30];
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uint32_t v_err = 0; //errors in viterbi decoder
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UNUSED(v_err);
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uint8_t m17_bits[368]; //368 bits that have been de-interleaved and de-scramble
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uint8_t m17_depunc[500]; //488 bits after depuncturing
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memset (dbuf, 0, sizeof(dbuf));
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memset (state->m17_lsf, 0, sizeof(state->m17_lsf));
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memset (m17_rnd_bits, 0, sizeof(m17_rnd_bits));
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memset (m17_int_bits, 0, sizeof(m17_int_bits));
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memset (m17_bits, 0, sizeof(m17_bits));
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memset (m17_rnd_bits, 0, sizeof(m17_rnd_bits));
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memset (m17_depunc, 0, sizeof(m17_depunc));
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memset (lsf_packed, 0, sizeof(lsf_packed));
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memset (lsf_bytes, 0, sizeof(lsf_bytes));
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//load dibits into dibit buffer
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for (i = 0; i < 184; i++)
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dbuf[i] = getDibit(opts, state);
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dbuf[i] = (uint8_t) getDibit(opts, state);
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//convert dbuf into a bit array
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for (i = 0; i < 184; i++)
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@ -762,108 +750,57 @@ void processM17LSF(dsd_opts * opts, dsd_state * state)
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m17_bits[i] = m17_int_bits[x];
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}
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//P1 Depuncture & Add Weights
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x = 0;
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j = 0; k = 0; x = 0;
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// P1 Depuncture
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for (i = 0; i < 488; i++)
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{
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if (p1[i%61] == 1)
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m17_depunc[i] = m17_bits[x++];
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else m17_depunc[i] = 0;
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//assign any puncture as a 0
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// if (p1[k++] == 1) m17_depunc[x++] = m17_bits[j++];
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// else m17_depunc[x++] = 0;
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if (m17_depunc[i])
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m17_depunc[i] = 0xFFFF;
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else m17_depunc[i] = 0x7FFF;
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}
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//trailing zeroes
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// for (i = 484; i < 488; i++)
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// m17_depunc[i] = 0x7FFF;
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//seems to be better if we use the last bit as an educated guess on what the next bit should be
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//this pseudo logic is based purely on 0xFFFFFFFFFF as Broadcast, and all zeroes as the Meta(IV)
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//debug -- fill all of the byte array
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// memset (m17_depunc, 0xFFFF, sizeof(m17_depunc));
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//debug
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// fprintf (stderr, "\n depunc: \n");
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// for (i = 0; i < 488; i++)
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// fprintf (stderr, " %04X", m17_depunc[i]);
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//use the libM17 Viterbi Decoder
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uint16_t len = 488;
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v_err = viterbi_decode(lsf_bytes, m17_depunc, len);
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// v_err -= 3932040; //cost negation (double check this as well as unit, meaning, etc)
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//debug
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// fprintf (stderr, "\n lsf_bytes: \n");
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// for (i = 0; i < 31; i++)
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// fprintf (stderr, " %02X", lsf_bytes[i]);
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//copy + left shift one octet
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memcpy (lsf_packed, lsf_bytes+1, 30);
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//Unpack bytes into m17_lsf bits
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k = 0;
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for (j = 0; j < 30; j++)
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{
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for (i = 0; i < 8; i++)
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state->m17_lsf[k++] = (lsf_packed[j] >> 7-i) & 1;
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}
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uint16_t crc_cmp = crc16m17(lsf_packed, 28);
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uint16_t crc_ext = (lsf_packed[28] << 8) + (lsf_packed[29] << 0);
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int crc_err = 0;
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if (crc_cmp != crc_ext) crc_err = 1;
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if (crc_err == 0)
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M17decodeLSF(state);
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else if (opts->aggressive_framesync == 0)
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M17decodeLSF(state);
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if (opts->payload == 1)
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{
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fprintf (stderr, "\n LSF: ");
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for (i = 0; i < 30; i++)
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//DST, or META field
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if (i < 48 || i > 96)
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{
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if (i == 15) fprintf (stderr, "\n ");
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fprintf (stderr, "[%02X]", lsf_packed[i]);
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if (p1[k++] == 1) m17_depunc[x++] = m17_bits[j++];
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else if (m17_depunc[x-2] == 1) m17_depunc[x++] = 1;
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else m17_depunc[x++] = 0;
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}
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// fprintf (stderr, " V Err: %d", v_err);
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else //any other field
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{
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if (p1[k++] == 1) m17_depunc[x++] = m17_bits[j++];
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else m17_depunc[x++] = 0;
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}
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if (k == 61) k = 0; //61 -- should reset 8 times againt the array
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}
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//debug
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// fprintf (stderr, " E-%04X; C-%04X (CRC CHK)", crc_ext, crc_cmp);
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//debug -- values seem okay at end of run
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// fprintf (stderr, "K = %d; J = %d; X = %d", k, j, x);
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if (crc_err == 1) fprintf (stderr, " CRC ERR");
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//debug deinterleaved bits
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// fprintf (stderr, "\n DEINT: ");
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// for (i = 0; i < 368; i++)
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// fprintf (stderr, "%d,", m17_bits[i]);
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//zero out after decoding
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memset (state->m17_lsf, 0, sizeof(state->m17_lsf));
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//ending linebreak
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fprintf (stderr, "\n");
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} //end processM17LSF
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//This version is the older method, skipping the depuncturing and just doing deconv
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void processM17LSF_debug(dsd_opts * opts, dsd_state * state, uint8_t * m17_depunc)
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{
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//NOTE: This version has been stripped down, but will not be used,
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//but will keep in case of future debug for ease of use
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int i, x; UNUSED(x);
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uint8_t m17_int_bits[368]; //368 bits that are still interleaved
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uint8_t m17_bits[368]; //368 bits that have been de-interleaved and de-scramble
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memset (m17_int_bits, 0, sizeof(m17_int_bits));
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memset (m17_bits, 0, sizeof(m17_bits));
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//debug depunctured bits
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// fprintf (stderr, "\n DEPUNC: ");
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// for (i = 0; i < 488; i++)
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// fprintf (stderr, "%d,", m17_depunc[i]);
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//setup the convolutional decoder
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uint8_t temp[488];
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uint8_t temp[500];
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uint8_t s0;
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uint8_t s1;
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uint8_t m_data[30];
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uint8_t trellis_buf[240]; //30*8 = 240
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uint8_t m_data[32];
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uint8_t trellis_buf[260]; //30*8 = 240
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memset (trellis_buf, 0, sizeof(trellis_buf));
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memset (temp, 0, sizeof (temp));
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memset (m_data, 0, sizeof (m_data));
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@ -914,7 +851,7 @@ void processM17LSF_debug(dsd_opts * opts, dsd_state * state, uint8_t * m17_depun
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if (crc_err == 0)
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M17decodeLSF(state);
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else if (opts->aggressive_framesync == 0)
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M17decodeLSF(state);
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M17decodeLSF(state);
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if (opts->payload == 1)
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{
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@ -924,10 +861,144 @@ void processM17LSF_debug(dsd_opts * opts, dsd_state * state, uint8_t * m17_depun
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if (i == 15) fprintf (stderr, "\n ");
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fprintf (stderr, "[%02X]", lsf_packed[i]);
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}
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fprintf (stderr, " (CRC CHK) E-%04X; C-%04X;", crc_ext, crc_cmp);
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}
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if (crc_err == 1) fprintf (stderr, " CRC ERR");
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//ending linebreak
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fprintf (stderr, "\n");
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} //end processM17LSF
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//This version is the older method, skipping the depuncturing and just doing deconv
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void processM17LSF_debug(dsd_opts * opts, dsd_state * state, uint8_t * m17_rnd_bits)
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{
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//NOTE: Why is this being a pain in the ass now?
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int i, j, k, x;
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uint8_t m17_int_bits[368]; //368 bits that are still interleaved
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uint8_t m17_bits[368]; //368 bits that have been de-interleaved and de-scramble
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uint8_t m17_depunc[500]; //488 bits after depuncturing
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memset (m17_int_bits, 0, sizeof(m17_int_bits));
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memset (m17_bits, 0, sizeof(m17_bits));
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memset (m17_depunc, 0, sizeof(m17_depunc));
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//descramble the frame
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for (i = 0; i < 368; i++)
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m17_int_bits[i] = (m17_rnd_bits[i] ^ m17_scramble[i]) & 1;
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//deinterleave the bit array using Quadratic Permutation Polynomial
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//function π(x) = (45x + 92x^2 ) mod 368
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for (i = 0; i < 368; i++)
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{
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x = ((45*i)+(92*i*i)) % 368;
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m17_bits[i] = m17_int_bits[x];
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}
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//debug
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// fprintf (stderr, " E-%04X; C-%04X (CRC CHK)", crc_ext, crc_cmp);
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j = 0; k = 0; x = 0;
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// P1 Depuncture
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for (i = 0; i < 488; i++)
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{
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//assign any puncture as a 0
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// if (p1[k++] == 1) m17_depunc[x++] = m17_bits[j++];
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// else m17_depunc[x++] = 0;
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//seems to be better if we use the last bit as an educated guess on what the next bit should be
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//this pseudo logic is based purely on 0xFFFFFFFFFF as Broadcast, and all zeroes as the Meta(IV)
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//DST, or META field
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if (i < 48 || i > 96)
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{
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if (p1[k++] == 1) m17_depunc[x++] = m17_bits[j++];
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else if (m17_depunc[x-2] == 1) m17_depunc[x++] = 1;
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else m17_depunc[x++] = 0;
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}
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else //any other field
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{
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if (p1[k++] == 1) m17_depunc[x++] = m17_bits[j++];
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else m17_depunc[x++] = 0;
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}
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if (k == 61) k = 0; //61 -- should reset 8 times againt the array
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}
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//setup the convolutional decoder
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uint8_t temp[500];
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uint8_t s0;
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uint8_t s1;
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uint8_t m_data[32];
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uint8_t trellis_buf[260]; //30*8 = 240
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memset (trellis_buf, 0, sizeof(trellis_buf));
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memset (temp, 0, sizeof (temp));
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memset (m_data, 0, sizeof (m_data));
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for (i = 0; i < 488; i++)
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temp[i] = m17_depunc[i] << 1;
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CNXDNConvolution_start();
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for (i = 0; i < 244; i++)
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{
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s0 = temp[(2*i)];
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s1 = temp[(2*i)+1];
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CNXDNConvolution_decode(s0, s1);
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}
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CNXDNConvolution_chainback(m_data, 240);
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//244/8 = 30, last 4 (244-248) are trailing zeroes
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for(i = 0; i < 30; i++)
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{
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trellis_buf[(i*8)+0] = (m_data[i] >> 7) & 1;
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trellis_buf[(i*8)+1] = (m_data[i] >> 6) & 1;
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trellis_buf[(i*8)+2] = (m_data[i] >> 5) & 1;
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trellis_buf[(i*8)+3] = (m_data[i] >> 4) & 1;
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trellis_buf[(i*8)+4] = (m_data[i] >> 3) & 1;
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trellis_buf[(i*8)+5] = (m_data[i] >> 2) & 1;
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trellis_buf[(i*8)+6] = (m_data[i] >> 1) & 1;
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trellis_buf[(i*8)+7] = (m_data[i] >> 0) & 1;
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}
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memset (state->m17_lsf, 0, sizeof(state->m17_lsf));
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memcpy (state->m17_lsf, trellis_buf, 240);
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uint8_t lsf_packed[30];
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memset (lsf_packed, 0, sizeof(lsf_packed));
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//need to pack bytes for the sw5wwp variant of the crc (might as well, may be useful in the future)
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for (i = 0; i < 30; i++)
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lsf_packed[i] = (uint8_t)ConvertBitIntoBytes(&state->m17_lsf[i*8], 8);
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uint16_t crc_cmp = crc16m17(lsf_packed, 28);
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uint16_t crc_ext = (uint16_t)ConvertBitIntoBytes(&state->m17_lsf[224], 16);
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int crc_err = 0;
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if (crc_cmp != crc_ext) crc_err = 1;
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if (crc_err == 0)
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M17decodeLSF(state);
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else if (opts->aggressive_framesync == 0)
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M17decodeLSF(state);
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if (opts->payload == 1)
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{
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fprintf (stderr, "\n LSF: ");
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for (i = 0; i < 30; i++)
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{
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if (i == 15) fprintf (stderr, "\n ");
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fprintf (stderr, "[%02X]", lsf_packed[i]);
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}
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fprintf (stderr, " (CRC CHK) E-%04X; C-%04X;", crc_ext, crc_cmp);
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}
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if (crc_err == 1) fprintf (stderr, " CRC ERR");
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@ -2089,7 +2160,7 @@ void encodeM17STR(dsd_opts * opts, dsd_state * state)
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fprintf (stderr, "\n M17 LSF (ENCODER): ");
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if (opts->monitor_input_audio == 0)
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processM17LSF_debug2(opts, state, m17_lsfs);
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processM17LSF_debug(opts, state, m17_lsfs);
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else fprintf (stderr, " To Audio Out Device Type: %d; ", opts->audio_out_type);
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//convert bit array into symbols and RF/Audio
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@ -2822,7 +2893,7 @@ void encodeM17PKT(dsd_opts * opts, dsd_state * state)
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{
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fprintf (stderr, "\n M17 LSF (ENCODER): ");
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processM17LSF_debug2(opts, state, m17_lsfs);
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processM17LSF_debug(opts, state, m17_lsfs);
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//convert bit array into symbols and RF/Audio
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memset (nil, 0, sizeof(nil));
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