MMDVMHost-Private/DMRTA.cpp

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/*
* Copyright (C) 2015,2016,2017,2018 Jonathan Naylor, G4KLX
* Copyright (C) 2018 by Shawn Chain, BG5HHP
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; version 2 of the License.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*/
#include "DMRTA.h"
#include "Log.h"
#include <cstring>
#include <cassert>
CDMRTA::CDMRTA() :
m_TA(),
m_buf()
{
}
CDMRTA::~CDMRTA()
{
}
bool CDMRTA::add(unsigned int blockId, const unsigned char* data, unsigned int len)
{
assert(data != NULL);
if (blockId > 3) {
// invalid block id
reset();
return false;
}
unsigned int offset = blockId * 7;
if (offset + len >= sizeof(m_buf)) {
// buffer overflow
reset();
return false;
}
::memcpy(m_buf + offset, data, len);
return decodeTA();
}
const unsigned char* CDMRTA::get()
{
return (unsigned char*)m_TA;
}
void CDMRTA::reset()
{
::memset(m_TA, 0, sizeof(m_TA));
::memset(m_buf, 0, sizeof(m_buf));
}
bool CDMRTA::decodeTA()
{
unsigned char *b;
unsigned char c;
int j;
unsigned int i, t1, t2;
unsigned char* talkerAlias = m_buf;
unsigned int TAformat = (talkerAlias[0] >> 6U) & 0x03U;
unsigned int TAsize = (talkerAlias[0] >> 1U) & 0x1FU;
::memcpy(m_TA, "(could not decode)", sizeof(m_TA));
switch (TAformat) {
case 0U: // 7 bit
::memset(m_TA, 0, sizeof(m_TA));
b = &talkerAlias[0];
t1 = 0U; t2 = 0U; c = 0U;
for (i = 0U; (i < 32U) && (t2 < TAsize); i++) {
for (j = 7; j >= 0; j--) {
c = (c << 1U) | (b[i] >> j);
if (++t1 == 7U) {
if (i > 0U)
m_TA[t2++] = c & 0x7FU;
t1 = 0U;
c = 0U;
}
}
}
m_TA[TAsize] = 0;
break;
case 1U: // ISO 8 bit
case 2U: // UTF8
::memcpy(m_TA, talkerAlias + 1U, sizeof(m_TA));
break;
case 3U: // UTF16 poor man's conversion
t2=0;
::memset(&m_TA, 0, sizeof(m_TA));
for (i = 0U; (i < 15U) && (t2 < TAsize); i++) {
if (talkerAlias[2U * i + 1U] == 0)
m_TA[t2++] = talkerAlias[2U * i + 2U];
else
m_TA[t2++] = '?';
}
m_TA[TAsize] = 0;
break;
}
size_t TAlen = ::strlen(m_TA);
LogMessage("DMR Talker Alias (Data Format %u, Received %u/%u char): '%s'", TAformat, TAlen, TAsize, m_TA);
if (TAlen > TAsize) {
if (TAlen < 29U)
strcat(m_TA, " ?");
else
strcpy(m_TA + 28U, " ?");
}
return TAlen >= TAsize;
}