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Fix bit stuffing and SSID in packet modulator

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This commit is contained in:
Jon Beniston 2021-01-13 17:12:14 +00:00
parent 1adfe3415c
commit 082904aa17
1 changed files with 54 additions and 15 deletions
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69
plugins/channeltx/modpacket/packetmodsource.cpp
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@ -25,6 +25,7 @@
#include "util/crc.h"
#include "util/messagequeue.h"
#include "maincore.h"
#include "channel/channelapi.h"
PacketModSource::PacketModSource() :
m_channelSampleRate(48000),
@ -424,33 +425,56 @@ void PacketModSource::applyChannelSettings(int channelSampleRate, int channelFre
}
}
static bool ax25_ssid(QByteArray& b, int i, int len, uint8_t& ssid)
{
if (b[i] == '-')
{
if (len > i + 1)
{
ssid = b[i+1] - '0';
if ((len > i + 2) && isdigit(b[i+2])) {
ssid = (ssid*10) + (b[i+2] - '0');
}
if (ssid >= 16)
{
qDebug() << "ax25_address: SSID greater than 15 not supported";
ssid = ssid & 0xf;
return false;
}
else
{
return true;
}
}
else
{
qDebug() << "ax25_address: SSID number missing";
return false;
}
}
else
return false;
}
static uint8_t *ax25_address(uint8_t *p, QString address, uint8_t crrl)
{
int len;
int i;
QByteArray b;
int ssid;
uint8_t ssid = 0;
bool hyphenSeen = false;
len = address.length();
b = address.toUtf8();
ssid = 0;
for (i = 0; i < 6; i++)
{
if ((i < len) && (ssid == 0))
if ((i < len) && !hyphenSeen)
{
if (b[i] == '-')
{
if (len > i + 1)
{
ssid = b[i+1] - '0';
if ((len > i + 2) && isdigit(b[i+2])) {
ssid = (ssid*10) + (b[i+1] - '0');
}
if (ssid >= 16)
qDebug() << "ax25_address: SSID greater than 15 not supported";
}
else
qDebug() << "ax25_address: SSID number missing";
ax25_ssid(b, i, len, ssid);
hyphenSeen = true;
*p++ = ' ' << 1;
}
else
@ -463,6 +487,10 @@ static uint8_t *ax25_address(uint8_t *p, QString address, uint8_t crrl)
*p++ = ' ' << 1;
}
}
if (b[i] == '-')
{
ax25_ssid(b, i, len, ssid);
}
*p++ = crrl | (ssid << 1);
return p;
@ -534,6 +562,7 @@ void PacketModSource::addTXPacket(QString callsign, QString to, QString via, QSt
{
uint8_t packet[AX25_MAX_BYTES];
uint8_t *crc_start;
uint8_t *packet_end;
uint8_t *p;
crc16x25 crc;
uint16_t crcValue;
@ -565,6 +594,7 @@ void PacketModSource::addTXPacket(QString callsign, QString to, QString via, QSt
crcValue = crc.get();
*p++ = crcValue & 0xff;
*p++ = (crcValue >> 8);
packet_end = p;
// Flag
for (int i = 0; i < std::min(m_settings.m_ax25PostFlags, AX25_MAX_FLAGS); i++)
*p++ = AX25_FLAG;
@ -582,8 +612,17 @@ void PacketModSource::addTXPacket(QString callsign, QString to, QString via, QSt
for (int j = 0; j < 8; j++)
{
int tx_bit = (packet[i] >> j) & 1;
// Stuff 0 if last 5 bits are 1s
if ((packet[i] != AX25_FLAG) && (m_last5Bits == 0x1f))
// Stuff 0 if last 5 bits are 1s, unless transmitting flag
// Except for special case of when last 5 bits of CRC are 1s
if ( ( (packet[i] != AX25_FLAG)
|| ( (&packet[i] >= crc_start)
&& ( (&packet[i] < packet_end)
|| ((&packet[i] == packet_end) && (j == 0))
)
)
)
&& (m_last5Bits == 0x1f)
)
addBit(0);
addBit(tx_bit);
}