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First version of the AX25 TX functionality.

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This commit is contained in:
Jonathan Naylor
2020-06-24 11:14:02 +01:00
parent 7ad70d04a4
commit 3de10fe98b
6 changed files with 215 additions and 7 deletions
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AX25Frame.cpp
+28
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@@ -54,6 +54,15 @@ const uint16_t CCITT_TABLE[] = {
0xf78f,0xe606,0xd49d,0xc514,0xb1ab,0xa022,0x92b9,0x8330,
0x7bc7,0x6a4e,0x58d5,0x495c,0x3de3,0x2c6a,0x1ef1,0x0f78 };
CAX25Frame::CAX25Frame(const uint8_t* data, uint16_t length) :
m_data(),
m_length(0U),
m_fcs(0U)
{
for (uint16_t i = 0U; i < length && i < (AX25_MAX_PACKET_LEN - 2U); i++)
m_data[m_length++] = data[i];
}
CAX25Frame::CAX25Frame() :
m_data(),
m_length(0U),
@@ -92,3 +101,22 @@ bool CAX25Frame::checkCRC()
}
}
void CAX25Frame::addCRC()
{
union {
uint16_t crc16;
uint8_t crc8[2U];
};
crc16 = 0xFFFFU;
for (uint16_t i = 0U; i < m_length; i++)
crc16 = uint16_t(crc8[1U]) ^ CCITT_TABLE[crc8[0U] ^ m_data[i]];
crc16 = ~crc16;
m_fcs = crc16;
m_data[m_length++] = crc8[0U];
m_data[m_length++] = crc8[1U];
}