/*
Copyright (C) 2019-2020 Andrei Kopanchuk UZ7HO
This file is part of QtSoundModem
QtSoundModem is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
QtSoundModem is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with QtSoundModem. If not, see http://www.gnu.org/licenses
*/
// UZ7HO Soundmodem Port by John Wiseman G8BPQ
#include "UZ7HOStuff.h"
//void fx25_encode_rs(byte * data, byte * parity, int pad, int rs_size);
//int fx25_decode_rs(byte * data, int * eras_pos, int no_eras, int pad, int rs_size);
#define FX25_FCR 1
#define FX25_PRIM 1
#define FX25_IPRIM 1
#define FX25_MM 8
#define FX25_NN 255
#define FX25_A0 FX25_NN
Byte FX25_ALPHA_TO[256] = {
0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40, 0x80, 0x1d, 0x3a, 0x74, 0xe8, 0xcd, 0x87, 0x13, 0x26,
0x4c, 0x98, 0x2d, 0x5a, 0xb4, 0x75, 0xea, 0xc9, 0x8f, 0x03, 0x06, 0x0c, 0x18, 0x30, 0x60, 0xc0,
0x9d, 0x27, 0x4e, 0x9c, 0x25, 0x4a, 0x94, 0x35, 0x6a, 0xd4, 0xb5, 0x77, 0xee, 0xc1, 0x9f, 0x23,
0x46, 0x8c, 0x05, 0x0a, 0x14, 0x28, 0x50, 0xa0, 0x5d, 0xba, 0x69, 0xd2, 0xb9, 0x6f, 0xde, 0xa1,
0x5f, 0xbe, 0x61, 0xc2, 0x99, 0x2f, 0x5e, 0xbc, 0x65, 0xca, 0x89, 0x0f, 0x1e, 0x3c, 0x78, 0xf0,
0xfd, 0xe7, 0xd3, 0xbb, 0x6b, 0xd6, 0xb1, 0x7f, 0xfe, 0xe1, 0xdf, 0xa3, 0x5b, 0xb6, 0x71, 0xe2,
0xd9, 0xaf, 0x43, 0x86, 0x11, 0x22, 0x44, 0x88, 0x0d, 0x1a, 0x34, 0x68, 0xd0, 0xbd, 0x67, 0xce,
0x81, 0x1f, 0x3e, 0x7c, 0xf8, 0xed, 0xc7, 0x93, 0x3b, 0x76, 0xec, 0xc5, 0x97, 0x33, 0x66, 0xcc,
0x85, 0x17, 0x2e, 0x5c, 0xb8, 0x6d, 0xda, 0xa9, 0x4f, 0x9e, 0x21, 0x42, 0x84, 0x15, 0x2a, 0x54,
0xa8, 0x4d, 0x9a, 0x29, 0x52, 0xa4, 0x55, 0xaa, 0x49, 0x92, 0x39, 0x72, 0xe4, 0xd5, 0xb7, 0x73,
0xe6, 0xd1, 0xbf, 0x63, 0xc6, 0x91, 0x3f, 0x7e, 0xfc, 0xe5, 0xd7, 0xb3, 0x7b, 0xf6, 0xf1, 0xff,
0xe3, 0xdb, 0xab, 0x4b, 0x96, 0x31, 0x62, 0xc4, 0x95, 0x37, 0x6e, 0xdc, 0xa5, 0x57, 0xae, 0x41,
0x82, 0x19, 0x32, 0x64, 0xc8, 0x8d, 0x07, 0x0e, 0x1c, 0x38, 0x70, 0xe0, 0xdd, 0xa7, 0x53, 0xa6,
0x51, 0xa2, 0x59, 0xb2, 0x79, 0xf2, 0xf9, 0xef, 0xc3, 0x9b, 0x2b, 0x56, 0xac, 0x45, 0x8a, 0x09,
0x12, 0x24, 0x48, 0x90, 0x3d, 0x7a, 0xf4, 0xf5, 0xf7, 0xf3, 0xfb, 0xeb, 0xcb, 0x8b, 0x0b, 0x16,
0x2c, 0x58, 0xb0, 0x7d, 0xfa, 0xe9, 0xcf, 0x83, 0x1b, 0x36, 0x6c, 0xd8, 0xad, 0x47, 0x8e, 0x00
};
Byte FX25_INDEX_OF[256] = {
255, 0, 1, 25, 2, 50, 26,198, 3,223, 51,238, 27,104,199, 75,
4,100,224, 14, 52,141,239,129, 28,193,105,248,200, 8, 76,113,
5,138,101, 47,225, 36, 15, 33, 53,147,142,218,240, 18,130, 69,
29,181,194,125,106, 39,249,185,201,154, 9,120, 77,228,114,166,
6,191,139, 98,102,221, 48,253,226,152, 37,179, 16,145, 34,136,
54,208,148,206,143,150,219,189,241,210, 19, 92,131, 56, 70, 64,
30, 66,182,163,195, 72,126,110,107, 58, 40, 84,250,133,186, 61,
202, 94,155,159, 10, 21,121, 43, 78,212,229,172,115,243,167, 87,
7,112,192,247,140,128, 99, 13,103, 74,222,237, 49,197,254, 24,
227,165,153,119, 38,184,180,124, 17, 68,146,217, 35, 32,137, 46,
55, 63,209, 91,149,188,207,205,144,135,151,178,220,252,190, 97,
242, 86,211,171, 20, 42, 93,158,132, 60, 57, 83, 71,109, 65,162,
31, 45, 67,216,183,123,164,118,196, 23, 73,236,127, 12,111,246,
108,161, 59, 82, 41,157, 85,170,251, 96,134,177,187,204, 62, 90,
203, 89, 95,176,156,169,160, 81, 11,245, 22,235,122,117, 44,215,
79,174,213,233,230,231,173,232,116,214,244,234,168, 80, 88,175
};
Byte FX25_CCSDS_poly_8[9] =
{ 29, 188, 142, 221, 118, 206, 52, 168, 0 };
Byte FX25_CCSDS_poly_16[17] =
{136,240,208,195,181,158,201,100, 11, 83,167,107,113,110,106,121, 0 };
Byte FX25_CCSDS_poly_32[33] = {
18,251,215, 28, 80,107,248, 53, 84,194, 91, 59,176, 99,203,137,
43,104,137, 0, 44,149,148,218, 75, 11,173,254,194,109, 8, 11,
0 };
Byte FX25_CCSDS_poly_64[65] = {
40, 21,218, 23, 48,237, 69, 6, 87, 42, 29,193,160,150,113, 32,
35,172,241,240,184, 90,188,225, 87,130,254, 41,245,253,184,241,
188,176, 54, 58,240,226,119,185, 77,150, 48,140,169,160, 96,217,
15,202,218,190,135,103,129, 77, 57,166,164, 12, 13,178, 53, 46,
0 };
integer FX25_NROOTS ;
Byte FX25_GENPOLY[256];
Byte MODNN(int x)
{
return x % 255;
}
void encode_rs(Byte * data, Byte * parity, int pad)
{
int i, j;
Byte feedback;
memset(parity, 0, FX25_NROOTS);
i = 0;
while (i < FX25_NN - FX25_NROOTS - pad)
{
feedback = FX25_INDEX_OF[data[i] ^ parity[0]];
if (feedback != FX25_A0)
{
j = 1;
while (j < FX25_NROOTS)
{
parity[j] = parity[j] ^ FX25_ALPHA_TO[MODNN(feedback + FX25_GENPOLY[FX25_NROOTS - j])];
j++;
}
}
move(&parity[1], &parity[0], FX25_NROOTS - 1);
if (feedback != FX25_A0)
parity[FX25_NROOTS - 1] = FX25_ALPHA_TO[MODNN(feedback + FX25_GENPOLY[0])];
else
parity[FX25_NROOTS - 1] = 0;
i++;
}
}
int FX25_MIN(int a, int b)
{
if (a > b)
return b;
else
return a;
}
int decode_rs(Byte * data, int * eras_pos, int no_eras, int pad)
{
int deg_lambda, el, deg_omega;
int i, j, r, k;
Byte q, tmp, num1, num2, den, discr_r;
Byte s[256];
Byte lambda[256];
Byte b[256];
Byte t[256];
Byte omega[256];
Byte root[256];
Byte reg[256];
Byte loc[256];
int syn_error, count = 0;
if (pad < 0 || pad>238)
return -1;
i = 0;
while (i < FX25_NROOTS)
{
s[i] = data[0];
i++;
}
j = 1;
while (j < FX25_NN - pad)
{
i = 0;
while (i < FX25_NROOTS)
{
if (s[i] == 0)
s[i] = data[j];
else
s[i] = data[j] ^ FX25_ALPHA_TO[MODNN(FX25_INDEX_OF[s[i]] + (FX25_FCR + i)*FX25_PRIM)];
i++;
}
j++;
}
syn_error = 0;
i = 0;
while (i < FX25_NROOTS)
{
syn_error = syn_error | s[i];
s[i] = FX25_INDEX_OF[s[i]];
i++;
}
if (syn_error == 0)
return count;
memset(&lambda[1], 0, FX25_NROOTS);
lambda[0] = 1;
i = 0;
while (i < FX25_NROOTS + 1)
{
b[i] = FX25_INDEX_OF[lambda[i]];
i++;
}
r = no_eras;
el = no_eras;
r++;
while (r <= FX25_NROOTS)
{
discr_r = 0;
i = 0;
while (i < r)
{
if (lambda[i] != 0 && s[r - i - 1] != FX25_A0)
discr_r = discr_r ^ FX25_ALPHA_TO[MODNN(FX25_INDEX_OF[lambda[i]] + s[r - i - 1])];
i++;
}
discr_r = FX25_INDEX_OF[discr_r];
if (discr_r == FX25_A0)
{
move(&b[0], &b[1], FX25_NROOTS);
b[0] = FX25_A0;
}
else
{
t[0] = lambda[0];
i = 0;
while (i < FX25_NROOTS)
{
if (b[i] != FX25_A0)
t[i + 1] = lambda[i + 1] ^ FX25_ALPHA_TO[MODNN(discr_r + b[i])];
else
t[i + 1] = lambda[i + 1];
i++;
}
if (2 * el <= r + no_eras - 1)
{
el = r + no_eras - el;
i = 0;
while (i <= FX25_NROOTS)
{
if (lambda[i] == 0)
b[i] = FX25_A0;
else
b[i] = MODNN(FX25_INDEX_OF[lambda[i]] - discr_r + FX25_NN);
i++;
}
}
else
{
move(&b[0], &b[1], FX25_NROOTS);
b[0] = FX25_A0;
}
move(t, lambda, FX25_NROOTS + 1);
}
r++;
}
deg_lambda = 0;
i = 0;
while (i < FX25_NROOTS + 1)
{
lambda[i] = FX25_INDEX_OF[lambda[i]];
if (lambda[i] != FX25_A0)
deg_lambda = i;
i++;
}
move(&lambda[1], ®[1], FX25_NROOTS);
count = 0;
i = 1;
k = FX25_IPRIM - 1;
while (i <= FX25_NN)
{
q = 1;
j = deg_lambda;
while (j > 0)
{
if (reg[j] != FX25_A0)
{
reg[j] = MODNN(reg[j] + j);
q = q ^ FX25_ALPHA_TO[reg[j]];
}
j--;
}
if (q == 0)
{
root[count] = i;
loc[count] = k;
count++;
if (count == deg_lambda)
break;
}
i++;
k = MODNN(k + FX25_IPRIM);
}
if (deg_lambda != count)
return -1;
deg_omega = deg_lambda - 1;
i = 0;
while (i <= deg_omega)
{
tmp = 0;
j = i;
while (j >= 0)
{
if (s[i - j] != FX25_A0 && lambda[j] != FX25_A0)
tmp = tmp ^ FX25_ALPHA_TO[MODNN(s[i - j] + lambda[j])];
j--;
}
omega[i] = FX25_INDEX_OF[tmp];
i++;
}
j = count - 1;
while (j >= 0)
{
num1 = 0;
i = deg_omega;
while (i >= 0)
{
if (omega[i] != FX25_A0)
num1 = num1 ^ FX25_ALPHA_TO[MODNN(omega[i] + i * root[j])];
i--;
}
num2 = FX25_ALPHA_TO[MODNN(root[j] * (FX25_FCR - 1) + FX25_NN)];
den = 0;
i = FX25_MIN(deg_lambda, FX25_NROOTS - 1) & 0xFE;
while (i >= 0)
{
if (lambda[i + 1] != FX25_A0)
den = den ^ FX25_ALPHA_TO[MODNN(lambda[i + 1] + i * root[j])];
i = i - 2;
}
if (num1 != 0 && loc[j] >= pad)
data[loc[j] - pad] = data[loc[j] - pad] ^ FX25_ALPHA_TO[MODNN(FX25_INDEX_OF[num1] + FX25_INDEX_OF[num2] + FX25_NN - FX25_INDEX_OF[den])];
j--;
}
return count;
}
void fx25_encode_rs(Byte * data, Byte *parity, int pad, int rs_size)
{
switch (rs_size)
{
case 8:
move(&FX25_CCSDS_poly_8[0], &FX25_GENPOLY[0], 9);
FX25_NROOTS = rs_size;
encode_rs(data, parity, 0);
return;
case 16:
move(&FX25_CCSDS_poly_16[0], &FX25_GENPOLY[0], 17);
FX25_NROOTS = rs_size;
encode_rs(data, parity, 0);
return;
case 32:
move(&FX25_CCSDS_poly_32[0], &FX25_GENPOLY[0], 33);
FX25_NROOTS = rs_size;
encode_rs(data, parity, 0);
return;
case 64:
move(&FX25_CCSDS_poly_64[0], &FX25_GENPOLY[0], 65);
FX25_NROOTS = rs_size;
encode_rs(data, parity, 0);
return;
}
}
int fx25_decode_rs(Byte * data, int * eras_pos, int no_eras, int pad, int rs_size)
{
switch (rs_size)
{
case 8:
move(&FX25_CCSDS_poly_8[0], &FX25_GENPOLY[0], 9);
FX25_NROOTS = rs_size;
return decode_rs(data, eras_pos, no_eras, pad);
case 16:
move(&FX25_CCSDS_poly_16[0], &FX25_GENPOLY[0], 17);
FX25_NROOTS = rs_size;
return decode_rs(data, eras_pos, no_eras, pad);
case 32:
move(&FX25_CCSDS_poly_32[0], &FX25_GENPOLY[0], 33);
FX25_NROOTS = rs_size;
return decode_rs(data, eras_pos, no_eras, pad);
case 64:
move(&FX25_CCSDS_poly_64[0], &FX25_GENPOLY[0], 65);
FX25_NROOTS = rs_size;
return decode_rs(data, eras_pos, no_eras, pad);
default:
return -1;
}
}