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Simplify the pre-emphasis code for AX.25.

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This commit is contained in:
Jonathan Naylor
2020-06-29 15:59:46 +01:00
parent a73376671c
commit 43f84ae968
3 changed files with 12 additions and 13 deletions
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AX25TX.cpp
+11 -9
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@@ -49,7 +49,6 @@ const q15_t AUDIO_TABLE_DATA[] = {
};
CAX25TX::CAX25TX() :
m_twist(-6),
m_poBuffer(),
m_poLen(0U),
m_poPtr(0U),
@@ -138,22 +137,25 @@ uint8_t CAX25TX::writeData(const uint8_t* data, uint16_t length)
void CAX25TX::writeBit(bool b)
{
q15_t in[AX25_RADIO_SYMBOL_LENGTH];
q15_t buffer[AX25_RADIO_SYMBOL_LENGTH];
for (uint8_t i = 0U; i < AX25_RADIO_SYMBOL_LENGTH; i++) {
in[i] = AUDIO_TABLE_DATA[m_tablePtr];
if (b)
q15_t value = AUDIO_TABLE_DATA[m_tablePtr];
if (b) {
m_tablePtr += 11U;
else
} else {
// De-emphasise the lower frequency by 6dB
value >>= 2;
m_tablePtr += 6U;
}
buffer[i] = value;
if (m_tablePtr >= AUDIO_TABLE_LEN)
m_tablePtr -= AUDIO_TABLE_LEN;
}
q15_t out[AX25_RADIO_SYMBOL_LENGTH];
m_twist.process(in, out, AX25_RADIO_SYMBOL_LENGTH);
io.write(STATE_AX25, out, AX25_RADIO_SYMBOL_LENGTH);
io.write(STATE_AX25, buffer, AX25_RADIO_SYMBOL_LENGTH);
}
void CAX25TX::setTXDelay(uint8_t delay)