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Convert the Goertzel algorithm to Q15 and Q31.

This commit is contained in:
Jonathan Naylor 2020-04-19 16:52:11 +01:00
parent 85816d5bec
commit f7e5c2436c
2 changed files with 99 additions and 75 deletions
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164
FMCTCSSRX.cpp
View File

@ -21,59 +21,59 @@
#include "FMCTCSSRX.h"
const struct CTCSS_TABLE {
uint8_t frequency;
float32_t coeff;
uint8_t frequency;
q31_t coeffDivTwo;
} CTCSS_TABLE_DATA[] = {
{ 67U, 1.999692},
{ 69U, 1.999671},
{ 71U, 1.999646},
{ 74U, 1.999621},
{ 77U, 1.999594},
{ 79U, 1.999565},
{ 82U, 1.999534},
{ 85U, 1.999500},
{ 88U, 1.999463},
{ 91U, 1.999426},
{ 94U, 1.999384},
{ 97U, 1.999350},
{100U, 1.999315},
{103U, 1.999266},
{107U, 1.999212},
{110U, 1.999157},
{114U, 1.999097},
{118U, 1.999033},
{123U, 1.998963},
{127U, 1.998889},
{131U, 1.998810},
{136U, 1.998723},
{141U, 1.998632},
{146U, 1.998535},
{151U, 1.998429},
{156U, 1.998317},
{159U, 1.998250},
{162U, 1.998197},
{165U, 1.998123},
{167U, 1.998068},
{171U, 1.997989},
{173U, 1.997930},
{177U, 1.997846},
{179U, 1.997782},
{183U, 1.997693},
{186U, 1.997624},
{189U, 1.997529},
{192U, 1.997453},
{196U, 1.997351},
{199U, 1.997273},
{203U, 1.997162},
{206U, 1.997078},
{210U, 1.996958},
{218U, 1.996741},
{225U, 1.996510},
{229U, 1.996404},
{233U, 1.996261},
{241U, 1.995994},
{250U, 1.995708},
{254U, 1.995576}};
{ 67U, 2147153298},
{ 69U, 2147130228},
{ 71U, 2147103212},
{ 74U, 2147076297},
{ 77U, 2147047330},
{ 79U, 2147016195},
{ 82U, 2146982775},
{ 85U, 2146946945},
{ 88U, 2146907275},
{ 91U, 2146867538},
{ 94U, 2146822298},
{ 97U, 2146785526},
{100U, 2146747759},
{103U, 2146695349},
{107U, 2146637984},
{110U, 2146578604},
{114U, 2146513835},
{118U, 2146445080},
{123U, 2146370355},
{127U, 2146291161},
{131U, 2146205372},
{136U, 2146112589},
{141U, 2146014479},
{146U, 2145910829},
{151U, 2145796971},
{156U, 2145676831},
{159U, 2145604646},
{162U, 2145547790},
{165U, 2145468230},
{167U, 2145409363},
{171U, 2145324517},
{173U, 2145261046},
{177U, 2145170643},
{179U, 2145102321},
{183U, 2145006080},
{186U, 2144932648},
{189U, 2144830280},
{192U, 2144748638},
{196U, 2144639788},
{199U, 2144555290},
{203U, 2144436713},
{206U, 2144346237},
{210U, 2144217348},
{218U, 2143983951},
{225U, 2143735870},
{229U, 2143622139},
{233U, 2143469001},
{241U, 2143182299},
{250U, 2142874683},
{254U, 2142733729}};
const uint8_t CTCSS_TABLE_DATA_LEN = 50U;
@ -81,11 +81,11 @@ const uint8_t CTCSS_TABLE_DATA_LEN = 50U;
const uint16_t N = 24000U / 4U;
CFMCTCSSRX::CFMCTCSSRX() :
m_coeff(0.0),
m_threshold(0.0),
m_coeffDivTwo(0),
m_threshold(0U),
m_count(0U),
m_q0(0.0),
m_q1(0.0),
m_q0(0),
m_q1(0),
m_result(false)
{
}
@ -94,36 +94,60 @@ uint8_t CFMCTCSSRX::setParams(uint8_t frequency, uint8_t threshold)
{
for (uint8_t i = 0U; i < CTCSS_TABLE_DATA_LEN; i++) {
if (CTCSS_TABLE_DATA[i].frequency == frequency) {
m_coeff = CTCSS_TABLE_DATA[i].coeff;
m_coeffDivTwo = CTCSS_TABLE_DATA[i].coeffDivTwo;
break;
}
}
if (m_coeff == 0.0)
if (m_coeffDivTwo == 0)
return 4U;
m_threshold = float32_t(threshold * threshold);
m_threshold = threshold * threshold;
return 0U;
}
bool CFMCTCSSRX::process(q15_t* samples, uint8_t length)
bool CFMCTCSSRX::process(const q15_t* samples, uint8_t length)
{
float32_t data[RX_BLOCK_SIZE];
::arm_q15_to_float(samples, data, length);
for (unsigned int i = 0U; i < length; i++) {
float32_t q2 = m_q1;
q31_t q2 = m_q1;
m_q1 = m_q0;
m_q0 = m_coeff * m_q1 - q2 + data[i];
// Q31 multiplication, t3 = m_coeffDivTwo * 2 * m_q1
q63_t t1 = m_coeffDivTwo * m_q1;
q31_t t2 = __SSAT(t1 >> 32, 31);
q31_t t3 = t2 * 2;
// Convert input data to Q31 from Q15
q31_t t4 = __SSAT(samples[i] << 16, 31);
// m_q0 = m_coeffDivTwo * m_q1 * 2 - q2 + samples[i]
m_q0 = t3 - q2 + t4;
m_count++;
if (m_count == N) {
float32_t value = m_q0 * m_q0 + m_q1 * m_q1 - m_q0 * m_q1 * m_coeff;
// Q31 multiplication, t2 = m_q0 * m_q0
q63_t t1 = m_q0 * m_q0;
q31_t t2 = __SSAT(t1 >> 32, 31);
// Q31 multiplication, t4 = m_q0 * m_q0
q63_t t3 = m_q1 * m_q1;
q31_t t4 = __SSAT(t3 >> 32, 31);
// Q31 multiplication, t9 = m_q0 * m_q1 * m_coeffDivTwo * 2
q63_t t5 = m_q0 * m_q1;
q31_t t6 = __SSAT(t5 >> 32, 31);
q63_t t7 = t6 * m_coeffDivTwo;
q31_t t8 = __SSAT(t7 >> 32, 31);
q31_t t9 = t8 * 2;
// value = m_q0 * m_q0 + m_q1 * m_q1 - m_q0 * m_q1 * m_coeffDivTwo * 2
q31_t value = t2 + t4 - t9;
m_result = value >= m_threshold;
m_count = 0U;
m_q0 = 0.0F;
m_q1 = 0.0F;
m_q0 = 0;
m_q1 = 0;
}
}
@ -132,8 +156,8 @@ bool CFMCTCSSRX::process(q15_t* samples, uint8_t length)
void CFMCTCSSRX::reset()
{
m_q0 = 0.0;
m_q1 = 0.0;
m_q0 = 0;
m_q1 = 0;
m_result = false;
m_count = 0U;
}

10
FMCTCSSRX.h
View File

@ -27,16 +27,16 @@ public:
uint8_t setParams(uint8_t frequency, uint8_t threshold);
bool process(q15_t* samples, uint8_t length);
bool process(const q15_t* samples, uint8_t length);
void reset();
private:
float32_t m_coeff;
float32_t m_threshold;
q31_t m_coeffDivTwo;
uint16_t m_threshold;
uint16_t m_count;
float m_q0;
float m_q1;
q31_t m_q0;
q31_t m_q1;
bool m_result;
};