FreeCalypso > hg > themwi-system-sw
annotate libutil/tfo_msg_enc.c @ 199:e6c7ced3c031
mgw: accept zero-length RTP payload as BFI
Mainline OsmoBTS now has an option (rtp continuous-streaming)
that causes it to emit an RTP packet every 20 ms without gaps,
sending a BFI marker in the form of zero-length RTP payload
when it has nothing else to send. These codec-independent
BFI markers don't indicate TAF, but this provision is a good
start. Accept this BFI packet format in themwi-mgw.
author | Mychaela Falconia <falcon@freecalypso.org> |
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date | Wed, 29 Mar 2023 20:23:43 -0800 |
parents | 05d01e810217 |
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rev | line source |
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194
05d01e810217
libutil: add TFO message gen function based on Osmocom crc8gen
Mychaela Falconia <falcon@freecalypso.org>
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1 /* |
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libutil: add TFO message gen function based on Osmocom crc8gen
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2 * The function implemented in this module encodes a GSM 08.62 Extension_Block. |
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libutil: add TFO message gen function based on Osmocom crc8gen
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3 */ |
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libutil: add TFO message gen function based on Osmocom crc8gen
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4 |
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5 #include <stdint.h> |
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6 #include "osmo_bits.h" |
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libutil: add TFO message gen function based on Osmocom crc8gen
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7 |
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8 /* |
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9 * EFR TRAU parity |
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10 * |
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11 * g(x) = x^3 + x^1 + 1 |
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12 */ |
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13 static const struct osmo_crc8gen_code gsm0860_efr_crc3 = { |
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14 .bits = 3, |
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15 .poly = 0x3, |
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16 .init = 0x0, |
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17 .remainder = 0x7, |
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18 }; |
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19 |
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20 void |
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21 encode_tfo_ext_words(bits_2_10, bits_12_15, ex, out) |
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22 unsigned bits_2_10, bits_12_15, ex; |
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23 uint16_t *out; |
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24 { |
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25 ubit_t crc_in[13]; |
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26 uint8_t crc; |
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27 |
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28 uint16_to_bits(bits_2_10, crc_in, 9); |
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29 uint16_to_bits(bits_12_15, crc_in + 9, 4); |
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30 crc = osmo_crc8gen_compute_bits(&gsm0860_efr_crc3, crc_in, 13); |
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31 out[0] = bits_2_10; |
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32 out[1] = (bits_12_15 << 5) | (crc << 2) | ex; |
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33 } |