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FT8: add encoding support to library and added more tests

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This commit is contained in:
f4exb
2024-03-28 15:15:48 +01:00
parent c833432675
commit 2e9fc9db64
21 changed files with 1330 additions and 493 deletions
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ft8/libldpc.cpp
+18 -17
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@@ -37,6 +37,7 @@
#include <math.h>
#include <stdlib.h>
#include "arrays.h"
#include "libldpc.h"
// float, long float, __float128
#define REAL float
@@ -48,7 +49,7 @@ namespace FT8
// returns the number of parity checks that passed.
// 83 means total success.
//
int ldpc_check(int codeword[])
int LDPC::ldpc_check(int codeword[])
{
int score = 0;
@@ -58,7 +59,7 @@ int ldpc_check(int codeword[])
int x = 0;
for (int ii1 = 0; ii1 < 7; ii1++)
{
int i1 = Nm[j][ii1] - 1;
int i1 = Arrays::Nm[j][ii1] - 1;
if (i1 >= 0)
{
x ^= codeword[i1];
@@ -75,7 +76,7 @@ int ldpc_check(int codeword[])
// iters is how hard to try.
// ok is the number of parity checks that worked out,
// ok == 83 means success.
void ldpc_decode(float llcodeword[], int iters, int plain[], int *ok)
void LDPC::ldpc_decode(float llcodeword[], int iters, int plain[], int *ok)
{
REAL m[83][174];
REAL e[83][174];
@@ -114,13 +115,13 @@ void ldpc_decode(float llcodeword[], int iters, int plain[], int *ok)
{
for (int ii1 = 0; ii1 < 7; ii1++)
{
int i1 = Nm[j][ii1] - 1;
int i1 = Arrays::Nm[j][ii1] - 1;
if (i1 < 0)
continue;
REAL a = 1.0;
for (int ii2 = 0; ii2 < 7; ii2++)
{
int i2 = Nm[j][ii2] - 1;
int i2 = Arrays::Nm[j][ii2] - 1;
if (i2 >= 0 && i2 != i1)
{
// tmp ranges from 1.0 to -1.0, for
@@ -145,7 +146,7 @@ void ldpc_decode(float llcodeword[], int iters, int plain[], int *ok)
REAL q1 = 1.0 - q0;
for (int j = 0; j < 3; j++)
{
int j2 = Mn[i][j] - 1;
int j2 = Arrays::Mn[i][j] - 1;
q0 *= e[j2][i];
q1 *= 1.0 - e[j2][i];
}
@@ -181,12 +182,12 @@ void ldpc_decode(float llcodeword[], int iters, int plain[], int *ok)
{
for (int ji1 = 0; ji1 < 3; ji1++)
{
int j1 = Mn[i][ji1] - 1;
int j1 = Arrays::Mn[i][ji1] - 1;
REAL q0 = codeword[i];
REAL q1 = 1.0 - q0;
for (int ji2 = 0; ji2 < 3; ji2++)
{
int j2 = Mn[i][ji2] - 1;
int j2 = Arrays::Mn[i][ji2] - 1;
if (j1 != j2)
{
q0 *= e[j2][i];
@@ -217,7 +218,7 @@ void ldpc_decode(float llcodeword[], int iters, int plain[], int *ok)
// thank you Douglas Bagnall
// https://math.stackexchange.com/a/446411
float fast_tanh(float x)
float LDPC::fast_tanh(float x)
{
if (x < -7.6)
{
@@ -256,7 +257,7 @@ return tanhtable[ind];
// iters is how hard to try.
// ok is the number of parity checks that worked out,
// ok == 83 means success.
void ldpc_decode_log(float codeword[], int iters, int plain[], int *ok)
void LDPC::ldpc_decode_log(float codeword[], int iters, int plain[], int *ok)
{
REAL m[83][174];
REAL e[83][174];
@@ -277,13 +278,13 @@ void ldpc_decode_log(float codeword[], int iters, int plain[], int *ok)
{
for (int ii1 = 0; ii1 < 7; ii1++)
{
int i1 = Nm[j][ii1] - 1;
int i1 = Arrays::Nm[j][ii1] - 1;
if (i1 < 0)
continue;
REAL a = 1.0;
for (int ii2 = 0; ii2 < 7; ii2++)
{
int i2 = Nm[j][ii2] - 1;
int i2 = Arrays::Nm[j][ii2] - 1;
if (i2 >= 0 && i2 != i1)
{
// a *= table_tanh(m[j][i2] / 2.0);
@@ -312,7 +313,7 @@ void ldpc_decode_log(float codeword[], int iters, int plain[], int *ok)
{
REAL l = codeword[i];
for (int j = 0; j < 3; j++)
l += e[Mn[i][j] - 1][i];
l += e[Arrays::Mn[i][j] - 1][i];
cw[i] = (l <= 0.0);
}
int score = ldpc_check(cw);
@@ -335,11 +336,11 @@ void ldpc_decode_log(float codeword[], int iters, int plain[], int *ok)
{
for (int ji1 = 0; ji1 < 3; ji1++)
{
int j1 = Mn[i][ji1] - 1;
int j1 = Arrays::Mn[i][ji1] - 1;
REAL l = codeword[i];
for (int ji2 = 0; ji2 < 3; ji2++)
{
int j2 = Mn[i][ji2] - 1;
int j2 = Arrays::Mn[i][ji2] - 1;
if (j1 != j2)
{
l += e[j2][i];
@@ -361,7 +362,7 @@ void ldpc_decode_log(float codeword[], int iters, int plain[], int *ok)
// check the FT8 CRC-14
//
void ft8_crc(int msg1[], int msglen, int out[14])
void LDPC::ft8_crc(int msg1[], int msglen, int out[14])
{
// the old FT8 polynomial for 12-bit CRC, 0xc06.
// int div[] = { 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 1, 1, 0 };
@@ -407,7 +408,7 @@ void ft8_crc(int msg1[], int msglen, int out[14])
// m[174][2*91].
// m's right half should start out as zeros.
// m's upper-right quarter will be the desired inverse.
void gauss_jordan(int rows, int cols, int m[174][2 * 91], int which[91], int *ok)
void LDPC::gauss_jordan(int rows, int cols, int m[174][2 * 91], int which[91], int *ok)
// gauss_jordan(int rows, int cols, int m[cols][2*rows], int which[rows], int *ok)
{
*ok = 0;