466 lines
13 KiB
C
466 lines
13 KiB
C
//NXDN frame handler
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//Reworked portions from Osmocom OP25 rx_sync.cc
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/* -*- c++ -*- */
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/*
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* NXDN Encoder/Decoder (C) Copyright 2019 Max H. Parke KA1RBI
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*
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*
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* This is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 3, or (at your option)
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* any later version.
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*
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* This software is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this software; see the file COPYING. If not, write to
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* the Free Software Foundation, Inc., 51 Franklin Street,
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* Boston, MA 02110-1301, USA.
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*/
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#include "dsd.h"
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#include "nxdn_const.h"
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#include <assert.h>
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void nxdn_frame (dsd_opts * opts, dsd_state * state)
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{
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// length is implicitly 192, with frame sync in first 10 dibits
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uint8_t dbuf[182];
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uint8_t lich;
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int answer_len = 0;
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uint8_t answer[32];
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uint8_t sacch_answer[32];
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int lich_parity_received;
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int lich_parity_computed;
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int voice = 0;
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int facch = 0;
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int facch2 = 0;
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int udch = 0;
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int sacch = 0;
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int cac = 0;
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int sr_structure;
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int sr_ran;
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//new, and even more confusing NXDN Type-D / "IDAS" acronyms
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int idas = 0;
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int scch = 0;
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int facch3 = 0;
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int udch2 = 0;
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//new breakdown of lich codes
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uint8_t lich_rf = 0; //RF Channel Type
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uint8_t lich_fc = 0; //Functional Channel Type
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uint8_t lich_op = 0; //Options
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uint8_t direction; //inbound or outbound direction
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uint8_t lich_dibits[8];
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uint8_t sacch_bits[60];
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uint8_t facch_bits_a[144];
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uint8_t facch_bits_b[144];
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uint8_t cac_bits[300];
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uint8_t facch2_bits[348]; //facch2 or udch, same amount of bits
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uint8_t facch3_bits[288]; //facch3 or udch2, same amoount of bits
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//nxdn bit buffer, for easy assignment handling
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int nxdn_bit_buffer[364];
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int nxdn_dibit_buffer[182];
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//init all arrays
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memset (dbuf, 0, sizeof(dbuf));
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memset (answer, 0, sizeof(answer));
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memset (sacch_answer, 0, sizeof(sacch_answer));
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memset (lich_dibits, 0, sizeof(lich_dibits));
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memset (sacch_bits, 0, sizeof(sacch_bits));
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memset (facch_bits_b, 0, sizeof(facch_bits_b));
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memset (facch_bits_a, 0, sizeof(facch_bits_a));
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memset (cac_bits, 0, sizeof(cac_bits));
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memset (facch2_bits, 0, sizeof(facch2_bits));
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memset (nxdn_bit_buffer, 0, sizeof(nxdn_bit_buffer));
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memset (nxdn_dibit_buffer, 0, sizeof(nxdn_dibit_buffer));
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//collect lich bits first, if they are good, then we can collect the rest of them
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for (int i = 0; i < 8; i++) lich_dibits[i] = dbuf[i] = getDibit(opts, state);
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nxdn_descramble (lich_dibits, 8);
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lich = 0;
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for (int i=0; i<8; i++) lich |= (lich_dibits[i] >> 1) << (7-i);
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lich_parity_received = lich & 1;
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lich_parity_computed = ((lich >> 7) + (lich >> 6) + (lich >> 5) + (lich >> 4)) & 1;
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lich = lich >> 1;
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if (lich_parity_received != lich_parity_computed)
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{
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if (opts->payload == 1) fprintf(stderr, " Lich Parity Error %02X\n", lich);
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state->lastsynctype = -1; //set to -1 so we don't jump back here too quickly
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goto END;
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}
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voice = 0;
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facch = 0;
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facch2 = 0;
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sacch = 0;
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cac = 0;
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//test for inbound direction lich when trunking (false positive) and skip
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//all inbound lich are even value (lsb is set to 0 for inbound direction)
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if (lich % 2 == 0 && opts->p25_trunk == 1)
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{
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if (opts->payload == 1) fprintf(stderr, " Simplex/Inbound NXDN lich on trunking system - type 0x%02X\n", lich);
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state->lastsynctype = -1; //set to -1 so we don't jump back here too quickly
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goto END;
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}
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switch(lich) { //cases without breaks continue to flow downwards until they hit the break
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case 0x01: // CAC types
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case 0x05:
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cac = 1;
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break;
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case 0x28: //facch2 types
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case 0x29:
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case 0x48:
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case 0x49:
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facch2 = 1;
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break;
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case 0x2e: //udch types
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case 0x2f:
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case 0x4e:
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case 0x4f:
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udch = 1;
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break;
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case 0x32: //facch in 1, vch in 2
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case 0x33:
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case 0x52:
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case 0x53:
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voice = 2;
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facch = 1;
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sacch = 1;
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break;
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case 0x34: //vch in 1, facch in 2
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case 0x35:
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case 0x54:
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case 0x55: //disabled for testing, IDAS system randomly triggers this one, probably due to poor signal
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voice = 1;
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facch = 2;
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sacch = 1;
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break;
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case 0x36: //vch in both
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case 0x37:
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case 0x56:
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case 0x57:
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voice = 3;
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facch = 0;
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sacch = 1;
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break;
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case 0x20: //facch in both
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case 0x21:
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case 0x30:
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case 0x31:
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case 0x40:
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case 0x41:
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case 0x50:
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case 0x51:
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voice = 0;
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facch = 3;
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sacch = 1;
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break;
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case 0x38: //sacch only (NULL?)
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case 0x39:
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sacch = 1;
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break;
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//NXDN "Type-D" or "IDAS" Specific Lich Codes
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case 0x76: //normal vch voice (in one and two)
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case 0x77:
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idas = 1;
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scch = 1;
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voice = 3;
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break;
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case 0x74: //vch in 1, facch1 in 2 (facch 2 steal)
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case 0x75:
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idas = 1;
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scch = 1;
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voice = 1;
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facch = 2;
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break;
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case 0x72: //facch in 1, vch in 2 (facch 1 steal)
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case 0x73:
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idas = 1;
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scch = 1;
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voice = 2;
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facch = 1;
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break;
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case 0x70: //facch steal in vch 1 and vch 2 (during voice only)
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case 0x71:
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idas = 1;
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scch = 1;
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facch = 3;
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break;
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case 0x6E: //udch2
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case 0x6F:
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idas = 1;
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scch = 1;
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udch2 = 1;
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break;
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case 0x68:
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case 0x69: //facch3
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idas = 1;
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scch = 1;
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facch3 = 1;
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break;
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case 0x62:
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case 0x63: //facch1 in 1, null data and post field in 2
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idas = 1;
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scch = 1;
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facch = 1;
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break;
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case 0x60:
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case 0x61: //facch1 in both (non vch)
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idas = 1;
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scch = 1;
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facch = 3;
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break;
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default:
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if (opts->payload == 1) fprintf(stderr, " false sync or unsupported NXDN lich type 0x%02X\n", lich);
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//reset the sacch field, we probably got a false sync and need to wipe or give a bad crc
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memset (state->nxdn_sacch_frame_segment, 1, sizeof(state->nxdn_sacch_frame_segment));
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memset (state->nxdn_sacch_frame_segcrc, 1, sizeof(state->nxdn_sacch_frame_segcrc));
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state->lastsynctype = -1; //set to -1 so we don't jump back here too quickly
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voice = 0;
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goto END;
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break;
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} // end of switch(lich)
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//enable these after good lich parity and known lich value
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state->carrier = 1;
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state->last_cc_sync_time = time(NULL);
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//printframesync after determining we have a good lich and it has something in it
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if (idas)
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{
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if (opts->frame_nxdn48 == 1)
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{
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printFrameSync (opts, state, "IDAS D ", 0, "-");
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}
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if (opts->payload == 1)
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fprintf (stderr, "L%02X - ", lich);
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}
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else if (voice || facch || sacch || facch2 || cac)
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{
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if (opts->frame_nxdn48 == 1)
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{
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printFrameSync (opts, state, "NXDN48 ", 0, "-");
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}
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else printFrameSync (opts, state, "NXDN96 ", 0, "-");
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if (opts->payload == 1)
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fprintf (stderr, "L%02X - ", lich);
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}
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//now that we have a good LICH, we can collect all of our dibits
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//and push them to the proper places for decoding (if LICH calls for that type)
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for (int i = 0; i < 174; i++) //192total-10FSW-8lich = 174
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{
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dbuf[i+8] = getDibit(opts, state);
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}
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nxdn_descramble (dbuf, 182); //sizeof(dbuf)
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//seperate our dbuf (dibit_buffer) into individual bit array
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for (int i = 0; i < 182; i++)
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{
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nxdn_bit_buffer[i*2] = dbuf[i] >> 1;
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nxdn_bit_buffer[i*2+1] = dbuf[i] & 1;
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}
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//sacch or scch bits
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for (int i = 0; i < 60; i++)
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{
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sacch_bits[i] = nxdn_bit_buffer[i+16];
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}
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//facch
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for (int i = 0; i < 144; i++)
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{
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facch_bits_a[i] = nxdn_bit_buffer[i+16+60];
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facch_bits_b[i] = nxdn_bit_buffer[i+16+60+144];
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}
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//cac
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for (int i = 0; i < 300; i++)
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{
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cac_bits[i] = nxdn_bit_buffer[i+16];
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}
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//udch or facch2
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for (int i = 0; i < 348; i++)
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{
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facch2_bits[i] = nxdn_bit_buffer[i+16];
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}
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//udch2 or facch3
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for (int i = 0; i < 288; i++)
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{
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facch3_bits[i] = nxdn_bit_buffer[i+16+60];
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}
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//vch frames stay inside dbuf, easier to assign that to ambe_fr frames
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//sacch needs extra handling depending on superframe or non-superframe variety
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//Add advanced decoding of LICH (RF, FC, OPT, and Direction
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lich_rf = (lich >> 5) & 0x3;
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lich_fc = (lich >> 3) & 0x3;
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lich_op = (lich >> 1) & 0x3;
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if (lich % 2 == 0) direction = 0;
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else direction = 1;
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// RF Channel Type
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if (lich_rf == 0) fprintf (stderr, "RCCH ");
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else if (lich_rf == 1) fprintf (stderr, "RTCH ");
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else if (lich_rf == 2) fprintf (stderr, "RDCH ");
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else
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{
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if (lich < 0x60) fprintf (stderr, "RTCH_C ");
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else fprintf (stderr, "RTCH2 ");
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}
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// Functional Channel Type -- things start to get really convoluted here
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// These will echo when handled, either with the decoded message type, or relevant crc err
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// if (lich_rf == 0) //CAC Type
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// {
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// //Technically, we should be checking direction as well, but the fc never has split meaning on CAC
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// if (lich_fc == 0) fprintf (stderr, "CAC ");
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// else if (lich_fc == 1) fprintf (stderr, "Long CAC ");
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// else if (lich_fc == 3) fprintf (stderr, "Short CAC ");
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// else fprintf (stderr, "Reserved ");
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// }
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// else //USC Type
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// {
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// if (lich_fc == 0) fprintf (stderr, "NSF SACCH ");
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// else if (lich_fc == 1) fprintf (stderr, "UDCH ");
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// else if (lich_fc == 2) fprintf (stderr, "SF SACCH ");
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// else if (lich_fc == 3) fprintf (stderr, "SF SACCH/IDLE ");
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// }
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//Option/Steal Flags echoed in Voice, V+F, or Data
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if (voice && !facch) //voice only, no facch steal
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{
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fprintf (stderr, "%s", KGRN);
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fprintf (stderr, " Voice ");
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fprintf (stderr, "%s", KNRM);
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}
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else if (voice && facch) //voice with facch1 steal
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{
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fprintf (stderr, "%s", KGRN);
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fprintf (stderr, " V%d+F%d ", 3 - facch, facch); //print which position on each
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fprintf (stderr, "%s", KNRM);
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}
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else //Covers FACCH1 in both, FACCH2, UDCH, UDCH2, CAC
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{
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fprintf (stderr, "%s", KCYN);
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fprintf (stderr, " Data ");
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fprintf (stderr, "%s", KNRM);
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//roll the voice scrambler LFSR here if key available to advance seed (usually just needed on NXDN96)
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if (state->nxdn_cipher_type == 0x1 && state->R != 0)
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{
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char ambe_temp[49] = {0};
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char ambe_d[49] = {0};
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for (int i = 0; i < 4; i++)
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{
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LFSRN(ambe_temp, ambe_d, state);
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}
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}
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}
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if (voice && facch == 1) //facch steal 1 -- before voice
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{
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//force scrambler here, but with unspecified key (just use what's loaded)
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if (state->M == 1 && state->R != 0) state->nxdn_cipher_type = 0x1;
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//roll the voice scrambler LFSR here if key available to advance seed -- half rotation on a facch steal
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if (state->nxdn_cipher_type == 0x1 && state->R != 0)
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{
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char ambe_temp[49] = {0};
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char ambe_d[49] = {0};
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for (int i = 0; i < 2; i++)
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{
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LFSRN(ambe_temp, ambe_d, state);
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}
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}
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}
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if (lich == 0x20 || lich == 0x21 || lich == 0x61 || lich == 0x40 || lich == 0x41) state->nxdn_sacch_non_superframe = TRUE;
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else state->nxdn_sacch_non_superframe = FALSE;
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//TODO Later: Add Direction and/or LICH to all decoding functions
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if (scch) nxdn_deperm_scch (opts, state, sacch_bits, direction);
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if (udch2) nxdn_deperm_facch3_udch2(opts, state, facch3_bits, 0);
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if (facch3) nxdn_deperm_facch3_udch2(opts, state, facch3_bits, 1);
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if (sacch) nxdn_deperm_sacch(opts, state, sacch_bits);
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if (cac) nxdn_deperm_cac(opts, state, cac_bits);
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//Seperated UDCH user data from facch2 data
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if (udch) nxdn_deperm_facch2_udch(opts, state, facch2_bits, 0);
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if (facch2) nxdn_deperm_facch2_udch(opts, state, facch2_bits, 1);
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//SHOULD be okay to run facch1's again on steal frames, will need testing
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if (facch & 1) nxdn_deperm_facch(opts, state, facch_bits_a);
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if (facch & 2) nxdn_deperm_facch(opts, state, facch_bits_b);
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if (voice)
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{
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//restore MBE file open here
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if ((opts->mbe_out_dir[0] != 0) && (opts->mbe_out_f == NULL)) openMbeOutFile (opts, state);
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//update last voice sync time
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state->last_vc_sync_time = time(NULL);
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//turn on scrambler if forced by user option
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if (state->M == 1 && state->R != 0) state->nxdn_cipher_type = 0x1;
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//process voice frame
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nxdn_voice (opts, state, voice, dbuf);
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}
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//close MBE file if no voice and its open
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if (!voice)
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{
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if (opts->mbe_out_f != NULL)
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{
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if (opts->frame_nxdn96 == 1) //nxdn96 has pure voice and data frames mixed together, so we will need to do a time check first
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{
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if ( (time(NULL) - state->last_vc_sync_time) > 1) //test for optimal time, 1 sec should be okay
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{
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closeMbeOutFile (opts, state);
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}
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}
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if (opts->frame_nxdn48 == 1) closeMbeOutFile (opts, state); //okay to close right away if nxdn48, no data/voice frames mixing
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}
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}
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if (voice && facch == 2) //facch steal 2 -- after voice 1
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{
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//roll the voice scrambler LFSR here if key available to advance seed -- half rotation on a facch steal
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if (state->nxdn_cipher_type == 0x1 && state->R != 0)
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{
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char ambe_temp[49] = {0};
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char ambe_d[49] = {0};
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for (int i = 0; i < 2; i++)
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{
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LFSRN(ambe_temp, ambe_d, state);
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}
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}
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}
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if (opts->payload == 1 && !voice) fprintf (stderr, "\n");
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else if (opts->payload == 0) fprintf (stderr, "\n");
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END: ; //do nothing
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}
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