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DroidStar/chamming.cpp

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/*
* Copyright (C) 2015,2016 by Jonathan Naylor G4KLX
*
* 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; either version 2 of the License, or
* (at your option) any later version.
*
* 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.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
#include "chamming.h"
#include <cstdio>
#include <cassert>
// Hamming (15,11,3) check a boolean data array
bool CHamming::decode15113_1(bool* d)
{
assert(d != NULL);
// Calculate the parity it should have
bool c0 = d[0] ^ d[1] ^ d[2] ^ d[3] ^ d[4] ^ d[5] ^ d[6];
bool c1 = d[0] ^ d[1] ^ d[2] ^ d[3] ^ d[7] ^ d[8] ^ d[9];
bool c2 = d[0] ^ d[1] ^ d[4] ^ d[5] ^ d[7] ^ d[8] ^ d[10];
bool c3 = d[0] ^ d[2] ^ d[4] ^ d[6] ^ d[7] ^ d[9] ^ d[10];
unsigned char n = 0U;
n |= (c0 != d[11]) ? 0x01U : 0x00U;
n |= (c1 != d[12]) ? 0x02U : 0x00U;
n |= (c2 != d[13]) ? 0x04U : 0x00U;
n |= (c3 != d[14]) ? 0x08U : 0x00U;
switch (n)
{
// Parity bit errors
case 0x01U: d[11] = !d[11]; return true;
case 0x02U: d[12] = !d[12]; return true;
case 0x04U: d[13] = !d[13]; return true;
case 0x08U: d[14] = !d[14]; return true;
// Data bit errors
case 0x0FU: d[0] = !d[0]; return true;
case 0x07U: d[1] = !d[1]; return true;
case 0x0BU: d[2] = !d[2]; return true;
case 0x03U: d[3] = !d[3]; return true;
case 0x0DU: d[4] = !d[4]; return true;
case 0x05U: d[5] = !d[5]; return true;
case 0x09U: d[6] = !d[6]; return true;
case 0x0EU: d[7] = !d[7]; return true;
case 0x06U: d[8] = !d[8]; return true;
case 0x0AU: d[9] = !d[9]; return true;
case 0x0CU: d[10] = !d[10]; return true;
// No bit errors
default: return false;
}
}
void CHamming::encode15113_1(bool* d)
{
assert(d != NULL);
// Calculate the checksum this row should have
d[11] = d[0] ^ d[1] ^ d[2] ^ d[3] ^ d[4] ^ d[5] ^ d[6];
d[12] = d[0] ^ d[1] ^ d[2] ^ d[3] ^ d[7] ^ d[8] ^ d[9];
d[13] = d[0] ^ d[1] ^ d[4] ^ d[5] ^ d[7] ^ d[8] ^ d[10];
d[14] = d[0] ^ d[2] ^ d[4] ^ d[6] ^ d[7] ^ d[9] ^ d[10];
}
// Hamming (15,11,3) check a boolean data array
bool CHamming::decode15113_2(bool* d)
{
assert(d != NULL);
// Calculate the checksum this row should have
bool c0 = d[0] ^ d[1] ^ d[2] ^ d[3] ^ d[5] ^ d[7] ^ d[8];
bool c1 = d[1] ^ d[2] ^ d[3] ^ d[4] ^ d[6] ^ d[8] ^ d[9];
bool c2 = d[2] ^ d[3] ^ d[4] ^ d[5] ^ d[7] ^ d[9] ^ d[10];
bool c3 = d[0] ^ d[1] ^ d[2] ^ d[4] ^ d[6] ^ d[7] ^ d[10];
unsigned char n = 0x00U;
n |= (c0 != d[11]) ? 0x01U : 0x00U;
n |= (c1 != d[12]) ? 0x02U : 0x00U;
n |= (c2 != d[13]) ? 0x04U : 0x00U;
n |= (c3 != d[14]) ? 0x08U : 0x00U;
switch (n) {
// Parity bit errors
case 0x01U: d[11] = !d[11]; return true;
case 0x02U: d[12] = !d[12]; return true;
case 0x04U: d[13] = !d[13]; return true;
case 0x08U: d[14] = !d[14]; return true;
// Data bit errors
case 0x09U: d[0] = !d[0]; return true;
case 0x0BU: d[1] = !d[1]; return true;
case 0x0FU: d[2] = !d[2]; return true;
case 0x07U: d[3] = !d[3]; return true;
case 0x0EU: d[4] = !d[4]; return true;
case 0x05U: d[5] = !d[5]; return true;
case 0x0AU: d[6] = !d[6]; return true;
case 0x0DU: d[7] = !d[7]; return true;
case 0x03U: d[8] = !d[8]; return true;
case 0x06U: d[9] = !d[9]; return true;
case 0x0CU: d[10] = !d[10]; return true;
// No bit errors
default: return false;
}
}
void CHamming::encode15113_2(bool* d)
{
assert(d != NULL);
// Calculate the checksum this row should have
d[11] = d[0] ^ d[1] ^ d[2] ^ d[3] ^ d[5] ^ d[7] ^ d[8];
d[12] = d[1] ^ d[2] ^ d[3] ^ d[4] ^ d[6] ^ d[8] ^ d[9];
d[13] = d[2] ^ d[3] ^ d[4] ^ d[5] ^ d[7] ^ d[9] ^ d[10];
d[14] = d[0] ^ d[1] ^ d[2] ^ d[4] ^ d[6] ^ d[7] ^ d[10];
}
// Hamming (13,9,3) check a boolean data array
bool CHamming::decode1393(bool* d)
{
assert(d != NULL);
// Calculate the checksum this column should have
bool c0 = d[0] ^ d[1] ^ d[3] ^ d[5] ^ d[6];
bool c1 = d[0] ^ d[1] ^ d[2] ^ d[4] ^ d[6] ^ d[7];
bool c2 = d[0] ^ d[1] ^ d[2] ^ d[3] ^ d[5] ^ d[7] ^ d[8];
bool c3 = d[0] ^ d[2] ^ d[4] ^ d[5] ^ d[8];
unsigned char n = 0x00U;
n |= (c0 != d[9]) ? 0x01U : 0x00U;
n |= (c1 != d[10]) ? 0x02U : 0x00U;
n |= (c2 != d[11]) ? 0x04U : 0x00U;
n |= (c3 != d[12]) ? 0x08U : 0x00U;
switch (n) {
// Parity bit errors
case 0x01U: d[9] = !d[9]; return true;
case 0x02U: d[10] = !d[10]; return true;
case 0x04U: d[11] = !d[11]; return true;
case 0x08U: d[12] = !d[12]; return true;
// Data bit erros
case 0x0FU: d[0] = !d[0]; return true;
case 0x07U: d[1] = !d[1]; return true;
case 0x0EU: d[2] = !d[2]; return true;
case 0x05U: d[3] = !d[3]; return true;
case 0x0AU: d[4] = !d[4]; return true;
case 0x0DU: d[5] = !d[5]; return true;
case 0x03U: d[6] = !d[6]; return true;
case 0x06U: d[7] = !d[7]; return true;
case 0x0CU: d[8] = !d[8]; return true;
// No bit errors
default: return false;
}
}
void CHamming::encode1393(bool* d)
{
assert(d != NULL);
// Calculate the checksum this column should have
d[9] = d[0] ^ d[1] ^ d[3] ^ d[5] ^ d[6];
d[10] = d[0] ^ d[1] ^ d[2] ^ d[4] ^ d[6] ^ d[7];
d[11] = d[0] ^ d[1] ^ d[2] ^ d[3] ^ d[5] ^ d[7] ^ d[8];
d[12] = d[0] ^ d[2] ^ d[4] ^ d[5] ^ d[8];
}
// Hamming (10,6,3) check a boolean data array
bool CHamming::decode1063(bool* d)
{
assert(d != NULL);
// Calculate the checksum this column should have
bool c0 = d[0] ^ d[1] ^ d[2] ^ d[5];
bool c1 = d[0] ^ d[1] ^ d[3] ^ d[5];
bool c2 = d[0] ^ d[2] ^ d[3] ^ d[4];
bool c3 = d[1] ^ d[2] ^ d[3] ^ d[4];
unsigned char n = 0x00U;
n |= (c0 != d[6]) ? 0x01U : 0x00U;
n |= (c1 != d[7]) ? 0x02U : 0x00U;
n |= (c2 != d[8]) ? 0x04U : 0x00U;
n |= (c3 != d[9]) ? 0x08U : 0x00U;
switch (n) {
// Parity bit errors
case 0x01U: d[6] = !d[6]; return true;
case 0x02U: d[7] = !d[7]; return true;
case 0x04U: d[8] = !d[8]; return true;
case 0x08U: d[9] = !d[9]; return true;
// Data bit erros
case 0x07U: d[0] = !d[0]; return true;
case 0x0BU: d[1] = !d[1]; return true;
case 0x0DU: d[2] = !d[2]; return true;
case 0x0EU: d[3] = !d[3]; return true;
case 0x0CU: d[4] = !d[4]; return true;
case 0x03U: d[5] = !d[5]; return true;
// No bit errors
default: return false;
}
}
void CHamming::encode1063(bool* d)
{
assert(d != NULL);
// Calculate the checksum this column should have
d[6] = d[0] ^ d[1] ^ d[2] ^ d[5];
d[7] = d[0] ^ d[1] ^ d[3] ^ d[5];
d[8] = d[0] ^ d[2] ^ d[3] ^ d[4];
d[9] = d[1] ^ d[2] ^ d[3] ^ d[4];
}
// A Hamming (16,11,4) Check
bool CHamming::decode16114(bool* d)
{
assert(d != NULL);
// Calculate the checksum this column should have
bool c0 = d[0] ^ d[1] ^ d[2] ^ d[3] ^ d[5] ^ d[7] ^ d[8];
bool c1 = d[1] ^ d[2] ^ d[3] ^ d[4] ^ d[6] ^ d[8] ^ d[9];
bool c2 = d[2] ^ d[3] ^ d[4] ^ d[5] ^ d[7] ^ d[9] ^ d[10];
bool c3 = d[0] ^ d[1] ^ d[2] ^ d[4] ^ d[6] ^ d[7] ^ d[10];
bool c4 = d[0] ^ d[2] ^ d[5] ^ d[6] ^ d[8] ^ d[9] ^ d[10];
// Compare these with the actual bits
unsigned char n = 0x00U;
n |= (c0 != d[11]) ? 0x01U : 0x00U;
n |= (c1 != d[12]) ? 0x02U : 0x00U;
n |= (c2 != d[13]) ? 0x04U : 0x00U;
n |= (c3 != d[14]) ? 0x08U : 0x00U;
n |= (c4 != d[15]) ? 0x10U : 0x00U;
switch (n) {
// Parity bit errors
case 0x01U: d[11] = !d[11]; return true;
case 0x02U: d[12] = !d[12]; return true;
case 0x04U: d[13] = !d[13]; return true;
case 0x08U: d[14] = !d[14]; return true;
case 0x10U: d[15] = !d[15]; return true;
// Data bit errors
case 0x19U: d[0] = !d[0]; return true;
case 0x0BU: d[1] = !d[1]; return true;
case 0x1FU: d[2] = !d[2]; return true;
case 0x07U: d[3] = !d[3]; return true;
case 0x0EU: d[4] = !d[4]; return true;
case 0x15U: d[5] = !d[5]; return true;
case 0x1AU: d[6] = !d[6]; return true;
case 0x0DU: d[7] = !d[7]; return true;
case 0x13U: d[8] = !d[8]; return true;
case 0x16U: d[9] = !d[9]; return true;
case 0x1CU: d[10] = !d[10]; return true;
// No bit errors
case 0x00U: return true;
// Unrecoverable errors
default: return false;
}
}
void CHamming::encode16114(bool* d)
{
assert(d != NULL);
d[11] = d[0] ^ d[1] ^ d[2] ^ d[3] ^ d[5] ^ d[7] ^ d[8];
d[12] = d[1] ^ d[2] ^ d[3] ^ d[4] ^ d[6] ^ d[8] ^ d[9];
d[13] = d[2] ^ d[3] ^ d[4] ^ d[5] ^ d[7] ^ d[9] ^ d[10];
d[14] = d[0] ^ d[1] ^ d[2] ^ d[4] ^ d[6] ^ d[7] ^ d[10];
d[15] = d[0] ^ d[2] ^ d[5] ^ d[6] ^ d[8] ^ d[9] ^ d[10];
}
// A Hamming (17,12,3) Check
bool CHamming::decode17123(bool* d)
{
assert(d != NULL);
// Calculate the checksum this column should have
bool c0 = d[0] ^ d[1] ^ d[2] ^ d[3] ^ d[6] ^ d[7] ^ d[9];
bool c1 = d[0] ^ d[1] ^ d[2] ^ d[3] ^ d[4] ^ d[7] ^ d[8] ^ d[10];
bool c2 = d[1] ^ d[2] ^ d[3] ^ d[4] ^ d[5] ^ d[8] ^ d[9] ^ d[11];
bool c3 = d[0] ^ d[1] ^ d[4] ^ d[5] ^ d[7] ^ d[10];
bool c4 = d[0] ^ d[1] ^ d[2] ^ d[5] ^ d[6] ^ d[8] ^ d[11];
// Compare these with the actual bits
unsigned char n = 0x00U;
n |= (c0 != d[12]) ? 0x01U : 0x00U;
n |= (c1 != d[13]) ? 0x02U : 0x00U;
n |= (c2 != d[14]) ? 0x04U : 0x00U;
n |= (c3 != d[15]) ? 0x08U : 0x00U;
n |= (c4 != d[16]) ? 0x10U : 0x00U;
switch (n) {
// Parity bit errors
case 0x01U: d[12] = !d[12]; return true;
case 0x02U: d[13] = !d[13]; return true;
case 0x04U: d[14] = !d[14]; return true;
case 0x08U: d[15] = !d[15]; return true;
case 0x10U: d[16] = !d[16]; return true;
// Data bit errors
case 0x1BU: d[0] = !d[0]; return true;
case 0x1FU: d[1] = !d[1]; return true;
case 0x17U: d[2] = !d[2]; return true;
case 0x07U: d[3] = !d[3]; return true;
case 0x0EU: d[4] = !d[4]; return true;
case 0x1CU: d[5] = !d[5]; return true;
case 0x11U: d[6] = !d[6]; return true;
case 0x0BU: d[7] = !d[7]; return true;
case 0x16U: d[8] = !d[8]; return true;
case 0x05U: d[9] = !d[9]; return true;
case 0x0AU: d[10] = !d[10]; return true;
case 0x14U: d[11] = !d[11]; return true;
// No bit errors
case 0x00U: return true;
// Unrecoverable errors
default: return false;
}
}
void CHamming::encode17123(bool* d)
{
assert(d != NULL);
d[12] = d[0] ^ d[1] ^ d[2] ^ d[3] ^ d[6] ^ d[7] ^ d[9];
d[13] = d[0] ^ d[1] ^ d[2] ^ d[3] ^ d[4] ^ d[7] ^ d[8] ^ d[10];
d[14] = d[1] ^ d[2] ^ d[3] ^ d[4] ^ d[5] ^ d[8] ^ d[9] ^ d[11];
d[15] = d[0] ^ d[1] ^ d[4] ^ d[5] ^ d[7] ^ d[10];
d[16] = d[0] ^ d[1] ^ d[2] ^ d[5] ^ d[6] ^ d[8] ^ d[11];
}
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