SSB_HighSpeed_Modem/hsmodem/constellation.cpp

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2020-11-05 13:11:57 -05:00
/*
* High Speed modem to transfer data in a 2,7kHz SSB channel
* =========================================================
* Author: DJ0ABR
*
* (c) DJ0ABR
* www.dj0abr.de
*
* 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 "hsmodem.h"
// functions for non-differential QPSK
// depending on the phase shift rotate a data blocks constellation
//uint8_t headerbytes[HEADERLEN] = {0x53, 0xe1, 0xa6};
// corresponds to these QPSK symbols:
// bits: 01010011 11100001 10100110
// syms: 1 1 0 3 3 2 0 1 2 2 1 2
uint8_t rxbytebuf[UDPBLOCKLEN+100]; // +100 ... reserve, just to be sure
uint8_t *convertQPSKSymToBytes(uint8_t *rxsymbols)
{
int sidx = 0;
for(int i=0; i<UDPBLOCKLEN; i++)
{
rxbytebuf[i] = rxsymbols[sidx++] << (bitsPerSymbol*3);
rxbytebuf[i] |= rxsymbols[sidx++] << (bitsPerSymbol*2);
rxbytebuf[i] |= rxsymbols[sidx++] << (bitsPerSymbol*1);
rxbytebuf[i] |= rxsymbols[sidx++] << (bitsPerSymbol*0);
}
return rxbytebuf;
}
void convertBytesToSyms_QPSK(uint8_t *bytes, uint8_t *syms, int bytenum)
{
unsigned int symidx = 0;
for(int i=0; i<bytenum; i++)
{
syms[symidx++] = (bytes[i] >> 6) & 3;
syms[symidx++] = (bytes[i] >> 4) & 3;
syms[symidx++] = (bytes[i] >> 2) & 3;
syms[symidx++] = (bytes[i] >> 0) & 3;
}
}
void rotateQPSKsyms(uint8_t *src, uint8_t *dst, int len)
{
for(int i=0; i<len; i++)
{
dst[i] = src[i] + 4;
dst[i]++;
dst[i] %= 4;
}
}
uint8_t QPSK_backbuf[UDPBLOCKLEN*8/2];
uint8_t *rotateBackQPSK(uint8_t *buf, int len, int rotations)
{
memcpy(QPSK_backbuf,buf,len);
for(unsigned int i=0; i<(unsigned int)len; i++)
{
for(int r=0; r<rotations; r++)
{
QPSK_backbuf[i] += 4;
QPSK_backbuf[i]--;
QPSK_backbuf[i] %= 4;
}
}
return QPSK_backbuf;
}
// works ONLY if number of bytes is a multiple of 3 !!!
void convertBytesToSyms_8PSK(uint8_t *bytes, uint8_t *syms, int bytenum)
{
unsigned int symidx = 0;
for(int i=0; i<bytenum; i+=3)
{
// convert next 3 bytes to 8 syms
syms[symidx++] = (bytes[0+i] >> 5) & 7;
syms[symidx++] = (bytes[0+i] >> 2) & 7;
syms[symidx++] = ((bytes[0+i] & 3) << 1) | ((bytes[1+i] >> 7) & 1);
syms[symidx++] = (bytes[1+i] >> 4) & 7;
syms[symidx++] = (bytes[1+i] >> 1) & 7;
syms[symidx++] = ((bytes[1+i] & 1) << 2) | ((bytes[2+i] >> 6) & 3);
syms[symidx++] = (bytes[2+i] >> 3) & 7;
syms[symidx++] = bytes[2+i] & 7;
}
}
void rotate8PSKsyms(uint8_t *src, uint8_t *dst, int len)
{
for(int i=0; i<len; i++)
{
dst[i] = src[i] + 8;
dst[i]++;
dst[i] %= 8;
}
}
void rotate8APSKsyms(uint8_t *src, uint8_t *dst, int len)
{
for(int i=0; i<len; i++)
{
if(src[i] == 0) dst[i] = 0;
else if(src[i] == 1) dst[i] = 4;
else if(src[i] == 2) dst[i] = 3;
else if(src[i] == 3) dst[i] = 1;
else if(src[i] == 4) dst[i] = 5;
else if(src[i] == 5) dst[i] = 7;
else if(src[i] == 6) dst[i] = 2;
else if(src[i] == 7) dst[i] = 6;
}
}
uint8_t _8PSK_backbuf[UDPBLOCKLEN*8/3];
uint8_t *rotateBack8PSK(uint8_t *buf, int len, int rotations)
{
memcpy(_8PSK_backbuf,buf,len);
for(int i=0; i<len; i++)
{
for(int r=0; r<rotations; r++)
{
_8PSK_backbuf[i] += 8;
_8PSK_backbuf[i]--;
_8PSK_backbuf[i] %= 8;
}
}
return _8PSK_backbuf;
}
uint8_t *rotateBack8APSK(uint8_t *buf, int len, int rotations)
{
memcpy(_8PSK_backbuf,buf,len);
for(int i=0; i<len; i++)
{
for(int r=0; r<rotations; r++)
{
if(_8PSK_backbuf[i] == 0) _8PSK_backbuf[i] = 0;
else if(_8PSK_backbuf[i] == 4) _8PSK_backbuf[i] = 1;
else if(_8PSK_backbuf[i] == 3) _8PSK_backbuf[i] = 2;
else if(_8PSK_backbuf[i] == 1) _8PSK_backbuf[i] = 3;
else if(_8PSK_backbuf[i] == 5) _8PSK_backbuf[i] = 4;
else if(_8PSK_backbuf[i] == 7) _8PSK_backbuf[i] = 5;
else if(_8PSK_backbuf[i] == 2) _8PSK_backbuf[i] = 6;
else if(_8PSK_backbuf[i] == 6) _8PSK_backbuf[i] = 7;
}
}
return _8PSK_backbuf;
}
uint8_t *convert8PSKSymToBytes(uint8_t *rxsymbols, int len)
{
int sidx = 0;
// works ONLY if total frame length is a multiple of 3 !
for(int i=0; i<len; i+=3)
{
rxbytebuf[i] = rxsymbols[sidx++] << 5;
rxbytebuf[i] |= rxsymbols[sidx++] << 2;
rxbytebuf[i] |= rxsymbols[sidx] >> 1;
rxbytebuf[i+1] = rxsymbols[sidx++] << 7;
rxbytebuf[i+1] |= rxsymbols[sidx++] << 4;
rxbytebuf[i+1] |= rxsymbols[sidx++] << 1;
rxbytebuf[i+1] |= rxsymbols[sidx] >> 2;
rxbytebuf[i+2] = rxsymbols[sidx++] << 6;
rxbytebuf[i+2] |= rxsymbols[sidx++] << 3;
rxbytebuf[i+2] |= rxsymbols[sidx++];
}
return rxbytebuf;
}
void shiftleft(uint8_t *data, int shiftnum, int len)
{
for(int j=0; j<shiftnum; j++)
{
int b1=0,b2=0;
for(int i=len-1; i>=0; i--)
{
b1 = (data[i] & 0x80)>>7;
data[i] <<= 1;
data[i] |= b2;
b2 = b1;
}
}
}