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Optimise the DC offset code.

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This commit is contained in:
Jonathan Naylor 2017-08-18 10:27:23 +01:00
parent 04ca97e5f8
commit 74682e7ac0
8 changed files with 44 additions and 90 deletions
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40
IO.cpp
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@ -22,6 +22,10 @@
#include "Globals.h"
#include "IO.h"
// Generated using [b, a] = butter(1, 0.001) in MATLAB
static q31_t DC_FILTER[] = {3367972, 0, 3367972, 0, 2140747704, 0}; // {b0, 0, b1, b2, -a1, -a2}
const uint32_t DC_FILTER_STAGES = 1U; // One Biquad stage
// Generated using rcosdesign(0.2, 8, 5, 'sqrt') in MATLAB
static q15_t RRC_0_2_FILTER[] = {401, 104, -340, -731, -847, -553, 112, 909, 1472, 1450, 683, -675, -2144, -3040, -2706, -770, 2667, 6995,
11237, 14331, 15464, 14331, 11237, 6995, 2667, -770, -2706, -3040, -2144, -675, 683, 1450, 1472, 909, 112,
@ -43,6 +47,8 @@ m_started(false),
m_rxBuffer(RX_RINGBUFFER_SIZE),
m_txBuffer(TX_RINGBUFFER_SIZE),
m_rssiBuffer(RX_RINGBUFFER_SIZE),
m_dcFilter(),
m_dcState(),
m_rrcFilter(),
m_gaussianFilter(),
m_boxcarFilter(),
@ -67,6 +73,12 @@ m_lockout(false)
::memset(m_rrcState, 0x00U, 70U * sizeof(q15_t));
::memset(m_gaussianState, 0x00U, 40U * sizeof(q15_t));
::memset(m_boxcarState, 0x00U, 30U * sizeof(q15_t));
::memset(m_dcState, 0x00U, 4U * sizeof(q31_t));
m_dcFilter.numStages = DC_FILTER_STAGES;
m_dcFilter.pState = m_dcState;
m_dcFilter.pCoeffs = DC_FILTER;
m_dcFilter.postShift = 0;
m_rrcFilter.numTaps = RRC_0_2_FILTER_LEN;
m_rrcFilter.pState = m_rrcState;
@ -157,21 +169,39 @@ void CIO::process()
if (m_lockout)
return;
q31_t dcLevel = 0;
q31_t dcVals[20U];
q31_t q31Samples[20U];
::arm_q15_to_q31(samples, q31Samples, length);
::arm_biquad_cascade_df1_q31(&m_dcFilter, q31Samples, dcVals, length);
for (uint8_t i = 0U; i < length; i++)
dcLevel += dcVals[i];
dcLevel /= length;
q15_t offset = q15_t(__SSAT((dcLevel >> 16), 16));;
q15_t dcSamples[RX_BLOCK_SIZE];
for (uint8_t i = 0U; i < length; i++)
dcSamples[i] = samples[i] - offset;
if (m_modemState == STATE_IDLE) {
if (m_dstarEnable) {
q15_t GMSKVals[RX_BLOCK_SIZE];
::arm_fir_fast_q15(&m_gaussianFilter, samples, GMSKVals, RX_BLOCK_SIZE);
::arm_fir_fast_q15(&m_gaussianFilter, dcSamples, GMSKVals, RX_BLOCK_SIZE);
dstarRX.samples(GMSKVals, rssi, RX_BLOCK_SIZE);
}
if (m_p25Enable) {
q15_t P25Vals[RX_BLOCK_SIZE];
::arm_fir_fast_q15(&m_boxcarFilter, samples, P25Vals, RX_BLOCK_SIZE);
::arm_fir_fast_q15(&m_boxcarFilter, dcSamples, P25Vals, RX_BLOCK_SIZE);
p25RX.samples(P25Vals, rssi, RX_BLOCK_SIZE);
}
// XXX YSF should use dcSamples, but DMR not
if (m_dmrEnable || m_ysfEnable) {
q15_t C4FSKVals[RX_BLOCK_SIZE];
::arm_fir_fast_q15(&m_rrcFilter, samples, C4FSKVals, RX_BLOCK_SIZE);
@ -189,7 +219,7 @@ void CIO::process()
} else if (m_modemState == STATE_DSTAR) {
if (m_dstarEnable) {
q15_t GMSKVals[RX_BLOCK_SIZE];
::arm_fir_fast_q15(&m_gaussianFilter, samples, GMSKVals, RX_BLOCK_SIZE);
::arm_fir_fast_q15(&m_gaussianFilter, dcSamples, GMSKVals, RX_BLOCK_SIZE);
dstarRX.samples(GMSKVals, rssi, RX_BLOCK_SIZE);
}
@ -211,14 +241,14 @@ void CIO::process()
} else if (m_modemState == STATE_YSF) {
if (m_ysfEnable) {
q15_t C4FSKVals[RX_BLOCK_SIZE];
::arm_fir_fast_q15(&m_rrcFilter, samples, C4FSKVals, RX_BLOCK_SIZE);
::arm_fir_fast_q15(&m_rrcFilter, dcSamples, C4FSKVals, RX_BLOCK_SIZE);
ysfRX.samples(C4FSKVals, rssi, RX_BLOCK_SIZE);
}
} else if (m_modemState == STATE_P25) {
if (m_p25Enable) {
q15_t P25Vals[RX_BLOCK_SIZE];
::arm_fir_fast_q15(&m_boxcarFilter, samples, P25Vals, RX_BLOCK_SIZE);
::arm_fir_fast_q15(&m_boxcarFilter, dcSamples, P25Vals, RX_BLOCK_SIZE);
p25RX.samples(P25Vals, rssi, RX_BLOCK_SIZE);
}