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Handle the P25 low speed data.

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This commit is contained in:
Jonathan Naylor
2016-09-20 06:53:30 +01:00
parent c8cb7a5429
commit 34bf8f18a7
8 changed files with 105 additions and 32 deletions
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71
P25LowSpeedData.cpp
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@@ -18,16 +18,81 @@
#include "P25LowSpeedData.h"
#include "P25Utils.h"
#include "Utils.h"
#include "Log.h"
#include <cstdio>
#include <cassert>
const unsigned int MAX_CCS_ERRS = 4U;
CP25LowSpeedData::CP25LowSpeedData()
{
}
CP25LowSpeedData::~CP25LowSpeedData()
{
}
void CP25LowSpeedData::process(unsigned char* data)
{
assert(data != NULL);
unsigned char lsd[4U];
CP25Utils::decode(data, lsd, 1546U, 1578U);
CUtils::dump(1U, "P25, Low Speed Data", lsd, 4U);
for (unsigned int a = 0x00U; a < 0x100U; a++) {
unsigned char ccs[2U];
ccs[0U] = a;
ccs[1U] = encode(ccs[0U]);
unsigned int errs = CP25Utils::compare(ccs, lsd + 0U, 2U);
if (errs < MAX_CCS_ERRS) {
lsd[0U] = ccs[0U];
lsd[1U] = ccs[1U];
break;
}
}
for (unsigned int a = 0x00U; a < 0x100U; a++) {
unsigned char ccs[2U];
ccs[0U] = a;
ccs[1U] = encode(ccs[0U]);
unsigned int errs = CP25Utils::compare(ccs, lsd + 2U, 2U);
if (errs < MAX_CCS_ERRS) {
lsd[2U] = ccs[0U];
lsd[3U] = ccs[1U];
break;
}
}
}
unsigned char CP25LowSpeedData::encode(unsigned char in)
{
unsigned char result = 0x00U;
if ((in & 0x01U) == 0x01U)
result ^= 0x39U;
if ((in & 0x02U) == 0x02U)
result ^= 0x72U;
if ((in & 0x04U) == 0x04U)
result ^= 0xE4U;
if ((in & 0x08U) == 0x08U)
result ^= 0xF1U;
if ((in & 0x10U) == 0x10U)
result ^= 0xDBU;
if ((in & 0x20U) == 0x20U)
result ^= 0x8FU;
if ((in & 0x40U) == 0x40U)
result ^= 0x27U;
if ((in & 0x80U) == 0x80U)
result ^= 0x4EU;
return result;
}