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M17 - Misc Cleanup and Reference Updates;

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lwvmobile
2024-03-06 11:52:53 -05:00
parent 404dc772d4
commit e7334a6c4f
1 changed files with 7 additions and 6 deletions
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13
src/m17.c
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@@ -1,9 +1,9 @@
/*-------------------------------------------------------------------------------
* m17.c
* M17 Decoder and Decoder (LSF and STR)
* M17 Decoder and Encoder
*
* m17_scramble Bit Array from SDR++
* CRC16 from M17-Implementations (thanks again, sp5wwp)
* CRC16, CSD encoder from libM17 / M17-Implementations (thanks again, sp5wwp)
*
* LWVMOBILE
* 2024-03 DSD-FME Florida Man Edition
@@ -46,7 +46,7 @@ uint8_t p1[62] = {
1, 1, 0, 1, 1, 1, 0, 1, 1, 1, 0, 1, 1
};
//from M17_Implementations -- sp5wwp -- should have just looked here to begin with
//from M17_Implementations / libM17 -- sp5wwp -- should have just looked here to begin with
//this setup looks very similar to the OP25 variant of crc16, but with a few differences (uses packed bytes)
uint16_t crc16m17(const uint8_t *in, const uint16_t len)
{
@@ -1170,6 +1170,7 @@ void encodeM17STR(dsd_opts * opts, dsd_state * state)
//NOTE: Most lich and lsf_chunk bits can be pre-set before the while loop,
//only need to refresh the lich_cnt value, nonce, and golay
uint16_t lsf_ps = 1; //packet or stream indicator bit
uint16_t lsf_dt = 2; //voice (3200bps)
uint16_t lsf_et = 0; //encryption type
uint16_t lsf_es = 0; //encryption sub-type
@@ -1178,7 +1179,7 @@ void encodeM17STR(dsd_opts * opts, dsd_state * state)
//compose the 16-bit frame information from the above sub elements
uint16_t lsf_fi = 0;
lsf_fi = (lsf_dt << 1) + (lsf_et << 3) + (lsf_es << 5) + (lsf_cn << 7) + (lsf_rs << 11);
lsf_fi = (lsf_ps & 1) + (lsf_dt << 1) + (lsf_et << 3) + (lsf_es << 5) + (lsf_cn << 7) + (lsf_rs << 11);
for (i = 0; i < 16; i++) m17_lsf[96+i] = (lsf_fi >> 15-i) & 1;
//Convert base40 CSD to numerical values (lifted from libM17)
@@ -1284,7 +1285,7 @@ void encodeM17STR(dsd_opts * opts, dsd_state * state)
m17_lsfs[i] = (m17_lsfi[i] ^ m17_scramble[i]) & 1;
fprintf (stderr, "\n M17 LSF (ENCODER): ");
processM17LSF_debug(opts, state, m17_lsfc);
processM17LSF_debug(opts, state, m17_lsfc);
//encodeM17RF
encodeM17RF (opts, state, m17_lsfs, 1);
@@ -1554,7 +1555,7 @@ void encodeM17STR(dsd_opts * opts, dsd_state * state)
for (i = 0; i < 368; i++)
m17_t4s[i] = (m17_t4i[i] ^ m17_scramble[i]) & 1;
//debug insert 3 random bit flips in the finished stream to test conv decoder
//debug insert 3 random bit flips in the finished stream to test conv/golay
// int rnd1 = rand()%368;
// int rnd2 = rand()%368;
// int rnd3 = rand()%368;