mirror of
https://github.com/lwvmobile/dsd-fme.git
synced 2026-11-14 09:47:30 -05:00
f8cd8d715f
Refactored implementation of p25p1_ldu1.c and p25p1_ldu2.c. There are less duplicities now and hopefully is easier to read and maintain. Added a unit test for the Hamming algorithm.
369 lines
10 KiB
C
369 lines
10 KiB
C
/*
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* Copyright (C) 2010 DSD Author
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* GPG Key ID: 0x3F1D7FD0 (74EF 430D F7F2 0A48 FCE6 F630 FAA2 635D 3F1D 7FD0)
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*
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* Permission to use, copy, modify, and/or distribute this software for any
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* purpose with or without fee is hereby granted, provided that the above
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* copyright notice and this permission notice appear in all copies.
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*
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* THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH
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* REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
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* AND FITNESS. IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT,
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* INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
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* LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
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* OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
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* PERFORMANCE OF THIS SOFTWARE.
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*/
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#include "dsd.h"
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#include "p25p1_check_hdu.h"
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/**
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* Read two bits from the stream of data. Takes into account the periodic occurrence of status bits.
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* Those are discarded.
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*/
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void
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read_dibit (dsd_opts* opts, dsd_state* state, char* output, int* status_count)
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{
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int dibit;
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int status;
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if (*status_count == 35) {
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// Status bits now
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status = getDibit (opts, state);
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// TODO: do something useful with the status bits...
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*status_count = 1;
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} else {
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(*status_count)++;
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}
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dibit = getDibit (opts, state);
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output[0] = (1 & (dibit >> 1)); // bit 1
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output[1] = (1 & dibit); // bit 0
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}
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/**
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* Read an hex word from the stream of data.
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*/
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void
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read_hex (dsd_opts* opts, dsd_state* state, char* hex, int* status_count)
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{
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unsigned int i;
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// Read 3 times a dibit = read 6 bits.
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for (i=0; i<=4; i+=2)
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{
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// We read two bits on each call
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read_dibit(opts, state, hex + i, status_count);
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}
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}
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/**
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* Read 12 bits from the stream of data. Those are the parity bits that follow each hex word.
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*/
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static void
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read_golay24_parity (dsd_opts* opts, dsd_state* state, char* parity, int* status_count)
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{
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unsigned int i;
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// Read 6 times a dibit = read 12 bits.
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for (i=0; i<=10; i+=2)
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{
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// We read two bits on each call
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read_dibit(opts, state, parity + i, status_count);
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}
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}
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static void
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correct_hex_word (dsd_state* state, char* hex, char* parity)
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{
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int fixed_errors;
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int irrecoverable_errors;
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irrecoverable_errors = check_and_fix_golay24(hex, parity, &fixed_errors);
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state->debug_header_errors += fixed_errors;
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if (irrecoverable_errors != 0)
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{
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state->debug_header_critical_errors++;
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}
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}
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/**
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* Read an hex word, its parity bits and attempts to error correct it using the Golay24 algorithm.
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*/
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static void
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read_and_correct_hex_word (dsd_opts* opts, dsd_state* state, char* hex, int* status_count)
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{
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char parity[12];
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// Read the hex word
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read_hex (opts, state, hex, status_count);
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// Read the parity
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read_golay24_parity (opts, state, parity, status_count);
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// Use the Golay24 FEC to correct it. This call modifies the content of hex to fix it, hopefully
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correct_hex_word (state, hex, parity);
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}
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void
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processHDU (dsd_opts * opts, dsd_state * state)
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{
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char mi[73], mfid[9], algid[9], kid[17], tgid[17], tmpstr[255];
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int dibit, i, j;
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long talkgroup;
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int algidhex, kidhex;
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char hex[6];
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int status_count;
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int status;
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char hex_data[20][6]; // Data in hex-words (6 bit words). A total of 20 hex words.
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char hex_parity[16][6]; // Parity of the data, again in hex-word format. A total of 16 parity hex words.
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int irrecoverable_errors;
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status_count = 35 - 14;
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// Read 20 hex words, correct them using their Golay24 parity data.
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for (i=19; i>=0; i--)
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{
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read_and_correct_hex_word (opts, state, hex, &status_count);
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// Store the corrected hex word into the hex_data store:
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for (j=0; j<6; j++)
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{
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hex_data[i][j] = hex[j];
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}
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}
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// Read the 16 parity hex word. These are used to FEC the 20 hex words using Reed-Solomon.
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for (i=15; i>=0; i--)
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{
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read_and_correct_hex_word (opts, state, hex, &status_count);
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// Store the corrected hex word into the hex_parity store:
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for (j=0; j<6; j++)
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{
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hex_parity[i][j] = hex[j];
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}
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}
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// Use the Reed-Solomon algorithm to correct the data. hex_data is modified in place
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irrecoverable_errors = check_and_fix_redsolomon_36_20_17((char*)hex_data, (char*)hex_parity);
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if (irrecoverable_errors != 0)
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{
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state->debug_header_critical_errors++;
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}
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mi[72] = 0;
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mfid[8] = 0;
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algid[8] = 0;
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kid[16] = 0;
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tgid[16] = 0;
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// Now put the corrected data on the DSD structures
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mi[ 0] = hex_data[19][0] + '0';
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mi[ 1] = hex_data[19][1] + '0';
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mi[ 2] = hex_data[19][2] + '0';
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mi[ 3] = hex_data[19][3] + '0';
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mi[ 4] = hex_data[19][4] + '0';
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mi[ 5] = hex_data[19][5] + '0';
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mi[ 6] = hex_data[18][0] + '0';
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mi[ 7] = hex_data[18][1] + '0';
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mi[ 8] = hex_data[18][2] + '0';
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mi[ 9] = hex_data[18][3] + '0';
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mi[10] = hex_data[18][4] + '0';
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mi[11] = hex_data[18][5] + '0';
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mi[12] = hex_data[17][0] + '0';
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mi[13] = hex_data[17][1] + '0';
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mi[14] = hex_data[17][2] + '0';
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mi[15] = hex_data[17][3] + '0';
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mi[16] = hex_data[17][4] + '0';
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mi[17] = hex_data[17][5] + '0';
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mi[18] = hex_data[16][0] + '0';
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mi[19] = hex_data[16][1] + '0';
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mi[20] = hex_data[16][2] + '0';
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mi[21] = hex_data[16][3] + '0';
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mi[22] = hex_data[16][4] + '0';
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mi[23] = hex_data[16][5] + '0';
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mi[24] = hex_data[15][0] + '0';
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mi[25] = hex_data[15][1] + '0';
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mi[26] = hex_data[15][2] + '0';
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mi[27] = hex_data[15][3] + '0';
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mi[28] = hex_data[15][4] + '0';
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mi[29] = hex_data[15][5] + '0';
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mi[30] = hex_data[14][0] + '0';
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mi[31] = hex_data[14][1] + '0';
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mi[32] = hex_data[14][2] + '0';
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mi[33] = hex_data[14][3] + '0';
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mi[34] = hex_data[14][4] + '0';
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mi[35] = hex_data[14][5] + '0';
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mi[36] = hex_data[13][0] + '0';
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mi[37] = hex_data[13][1] + '0';
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mi[38] = hex_data[13][2] + '0';
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mi[39] = hex_data[13][3] + '0';
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mi[40] = hex_data[13][4] + '0';
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mi[41] = hex_data[13][5] + '0';
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mi[42] = hex_data[12][0] + '0';
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mi[43] = hex_data[12][1] + '0';
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mi[44] = hex_data[12][2] + '0';
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mi[45] = hex_data[12][3] + '0';
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mi[46] = hex_data[12][4] + '0';
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mi[47] = hex_data[12][5] + '0';
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mi[48] = hex_data[11][0] + '0';
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mi[49] = hex_data[11][1] + '0';
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mi[50] = hex_data[11][2] + '0';
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mi[51] = hex_data[11][3] + '0';
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mi[52] = hex_data[11][4] + '0';
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mi[53] = hex_data[11][5] + '0';
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mi[54] = hex_data[10][0] + '0';
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mi[55] = hex_data[10][1] + '0';
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mi[56] = hex_data[10][2] + '0';
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mi[57] = hex_data[10][3] + '0';
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mi[58] = hex_data[10][4] + '0';
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mi[59] = hex_data[10][5] + '0';
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mi[60] = hex_data[9][0] + '0';
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mi[61] = hex_data[9][1] + '0';
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mi[62] = hex_data[9][2] + '0';
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mi[63] = hex_data[9][3] + '0';
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mi[64] = hex_data[9][4] + '0';
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mi[65] = hex_data[9][5] + '0';
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mi[66] = hex_data[8][0] + '0';
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mi[67] = hex_data[8][1] + '0';
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mi[68] = hex_data[8][2] + '0';
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mi[69] = hex_data[8][3] + '0';
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mi[70] = hex_data[8][4] + '0';
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mi[71] = hex_data[8][5] + '0';
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mfid[0] = hex_data[7][0] + '0';
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mfid[1] = hex_data[7][1] + '0';
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mfid[2] = hex_data[7][2] + '0';
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mfid[3] = hex_data[7][3] + '0';
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mfid[4] = hex_data[7][4] + '0';
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mfid[5] = hex_data[7][5] + '0';
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mfid[6] = hex_data[6][0] + '0';
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mfid[7] = hex_data[6][1] + '0';
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algid[0] = hex_data[6][2] + '0'; // The important algorithm ID. This indicates whether the data is
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algid[1] = hex_data[6][3] + '0'; // encrypted and if so what is the encryption algorithm used.
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algid[2] = hex_data[6][4] + '0'; // A code 0x80 here means that the data is unencrypted.
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algid[3] = hex_data[6][5] + '0';
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algid[4] = hex_data[5][0] + '0';
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algid[5] = hex_data[5][1] + '0';
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algid[6] = hex_data[5][2] + '0';
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algid[7] = hex_data[5][3] + '0';
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kid[ 0] = hex_data[5][4] + '0';
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kid[ 1] = hex_data[5][5] + '0';
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kid[ 2] = hex_data[4][0] + '0'; // The encryption key ID
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kid[ 3] = hex_data[4][1] + '0';
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kid[ 4] = hex_data[4][2] + '0';
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kid[ 5] = hex_data[4][3] + '0';
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kid[ 6] = hex_data[4][4] + '0';
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kid[ 7] = hex_data[4][5] + '0';
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kid[ 8] = hex_data[3][0] + '0';
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kid[ 9] = hex_data[3][1] + '0';
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kid[10] = hex_data[3][2] + '0';
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kid[11] = hex_data[3][3] + '0';
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kid[12] = hex_data[3][4] + '0';
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kid[13] = hex_data[3][5] + '0';
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kid[14] = hex_data[2][0] + '0';
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kid[15] = hex_data[2][1] + '0';
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tgid[ 0] = hex_data[2][2] + '0'; // Talk group ID
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tgid[ 1] = hex_data[2][3] + '0';
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tgid[ 2] = hex_data[2][4] + '0';
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tgid[ 3] = hex_data[2][5] + '0';
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tgid[ 4] = hex_data[1][0] + '0';
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tgid[ 5] = hex_data[1][1] + '0';
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tgid[ 6] = hex_data[1][2] + '0';
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tgid[ 7] = hex_data[1][3] + '0';
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tgid[ 8] = hex_data[1][4] + '0';
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tgid[ 9] = hex_data[1][5] + '0';
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tgid[10] = hex_data[0][0] + '0';
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tgid[11] = hex_data[0][1] + '0';
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tgid[12] = hex_data[0][2] + '0';
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tgid[13] = hex_data[0][3] + '0';
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tgid[14] = hex_data[0][4] + '0';
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tgid[15] = hex_data[0][5] + '0';
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state->p25kid = strtol(kid, NULL, 2);
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skipDibit (opts, state, 5);
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status = getDibit (opts, state);
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//TODO: Do something useful with the status bits...
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if (opts->p25enc == 1)
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{
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algidhex = strtol (algid, NULL, 2);
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kidhex = strtol (kid, NULL, 2);
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printf ("mi: %s algid: $%x kid: $%x\n", mi, algidhex, kidhex);
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}
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if (opts->p25lc == 1)
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{
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printf ("mfid: %s tgid: %s ", mfid, tgid);
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if (opts->p25tg == 0)
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{
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printf ("\n");
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}
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}
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j = 0;
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if (strcmp (mfid, "10010000") == 0)
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{
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for (i = 4; i < 16; i++)
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{
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if (state->tgcount < 24)
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{
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state->tg[state->tgcount][j] = tgid[i];
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}
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tmpstr[j] = tgid[i];
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j++;
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}
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tmpstr[12] = '0';
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tmpstr[13] = '0';
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tmpstr[14] = '0';
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tmpstr[15] = '0';
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}
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else
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{
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for (i = 0; i < 16; i++)
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{
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if (state->tgcount < 24)
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{
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state->tg[state->tgcount][j] = tgid[i];
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}
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tmpstr[j] = tgid[i];
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j++;
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}
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}
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tmpstr[16] = 0;
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talkgroup = strtol (tmpstr, NULL, 2);
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state->lasttg = talkgroup;
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if (state->tgcount < 24)
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{
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state->tgcount = state->tgcount + 1;
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}
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if (opts->p25tg == 1)
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{
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printf ("tg: %li\n", talkgroup);
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}
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}
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