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kgoba-ft8_lib/utils/ldpc.py

434 wiersze
9.2 KiB
Python
Czysty Wina Historia

import numpy as np
FTX_LDPC_N = 174
FTX_LDPC_M = 83
def ldpc_check(codeword):
errors = 0
for m in range(FTX_LDPC_M):
x = False
for i in range(kFTX_LDPC_Num_rows[m]):
x ^= codeword[kFTX_LDPC_Nm[m][i] - 1] > 0
if x:
errors += 1
return errors
def bp_solve(codeword, max_iters=25, max_no_improvement=5):
tov = np.zeros((FTX_LDPC_N, 3))
toc = np.zeros((FTX_LDPC_M, 7))
# int min_errors = FTX_LDPC_M;
min_errors = FTX_LDPC_M
last_errors = FTX_LDPC_M
plain = None
no_improvement = 1
for iter in range(max_iters):
# Do a hard decision guess (tov=0 in iter 0)
plain = np.where((codeword + tov[:, 0] + tov[:, 1] + tov[:, 2]) > 0, 1, 0)
if np.sum(plain) == 0:
# Message converged to all-zeros, which is prohibited
break
# Check to see if we have a codeword (check before we do any iter)
errors = ldpc_check(plain)
# print(f"iter {iter}, errors {errors}")
if errors < last_errors:
no_improvement = 1
last_errors = errors
else:
no_improvement += 1
if no_improvement >= max_no_improvement:
break
if errors < min_errors:
# We have a better guess - update the result
min_errors = errors
if errors == 0:
# Found a perfect answer
break
# Send messages from bits to check nodes
for m in range(FTX_LDPC_M):
for n_idx in range(kFTX_LDPC_Num_rows[m]):
n = kFTX_LDPC_Nm[m][n_idx] - 1
# for each (n, m)
Tnm = codeword[n]
for m_idx in range(3):
if (kFTX_LDPC_Mn[n][m_idx] - 1) != m:
Tnm += tov[n][m_idx]
toc[m][n_idx] = np.tanh(-Tnm / 2)
# Send messages from check nodes to variable nodes
for n in range(FTX_LDPC_N):
for m_idx in range(3):
m = kFTX_LDPC_Mn[n][m_idx] - 1
# for each (n, m)
Tmn = 1.0
for n_idx in range(kFTX_LDPC_Num_rows[m]):
if (kFTX_LDPC_Nm[m][n_idx] - 1) != n:
Tmn *= toc[m][n_idx]
tov[n][m_idx] = -2 * np.arctanh(Tmn)
return (plain, min_errors, iter)
# Each row describes one LDPC parity check.
# Each number is an index into the codeword (1-origin).
# The codeword bits mentioned in each row must XOR to zero.
kFTX_LDPC_Nm = [
[4, 31, 59, 91, 92, 96, 153],
[5, 32, 60, 93, 115, 146, 0],
[6, 24, 61, 94, 122, 151, 0],
[7, 33, 62, 95, 96, 143, 0],
[8, 25, 63, 83, 93, 96, 148],
[6, 32, 64, 97, 126, 138, 0],
[5, 34, 65, 78, 98, 107, 154],
[9, 35, 66, 99, 139, 146, 0],
[10, 36, 67, 100, 107, 126, 0],
[11, 37, 67, 87, 101, 139, 158],
[12, 38, 68, 102, 105, 155, 0],
[13, 39, 69, 103, 149, 162, 0],
[8, 40, 70, 82, 104, 114, 145],
[14, 41, 71, 88, 102, 123, 156],
[15, 42, 59, 106, 123, 159, 0],
[1, 33, 72, 106, 107, 157, 0],
[16, 43, 73, 108, 141, 160, 0],
[17, 37, 74, 81, 109, 131, 154],
[11, 44, 75, 110, 121, 166, 0],
[45, 55, 64, 111, 130, 161, 173],
[8, 46, 71, 112, 119, 166, 0],
[18, 36, 76, 89, 113, 114, 143],
[19, 38, 77, 104, 116, 163, 0],
[20, 47, 70, 92, 138, 165, 0],
[2, 48, 74, 113, 128, 160, 0],
[21, 45, 78, 83, 117, 121, 151],
[22, 47, 58, 118, 127, 164, 0],
[16, 39, 62, 112, 134, 158, 0],
[23, 43, 79, 120, 131, 145, 0],
[19, 35, 59, 73, 110, 125, 161],
[20, 36, 63, 94, 136, 161, 0],
[14, 31, 79, 98, 132, 164, 0],
[3, 44, 80, 124, 127, 169, 0],
[19, 46, 81, 117, 135, 167, 0],
[7, 49, 58, 90, 100, 105, 168],
[12, 50, 61, 118, 119, 144, 0],
[13, 51, 64, 114, 118, 157, 0],
[24, 52, 76, 129, 148, 149, 0],
[25, 53, 69, 90, 101, 130, 156],
[20, 46, 65, 80, 120, 140, 170],
[21, 54, 77, 100, 140, 171, 0],
[35, 82, 133, 142, 171, 174, 0],
[14, 30, 83, 113, 125, 170, 0],
[4, 29, 68, 120, 134, 173, 0],
[1, 4, 52, 57, 86, 136, 152],
[26, 51, 56, 91, 122, 137, 168],
[52, 84, 110, 115, 145, 168, 0],
[7, 50, 81, 99, 132, 173, 0],
[23, 55, 67, 95, 172, 174, 0],
[26, 41, 77, 109, 141, 148, 0],
[2, 27, 41, 61, 62, 115, 133],
[27, 40, 56, 124, 125, 126, 0],
[18, 49, 55, 124, 141, 167, 0],
[6, 33, 85, 108, 116, 156, 0],
[28, 48, 70, 85, 105, 129, 158],
[9, 54, 63, 131, 147, 155, 0],
[22, 53, 68, 109, 121, 174, 0],
[3, 13, 48, 78, 95, 123, 0],
[31, 69, 133, 150, 155, 169, 0],
[12, 43, 66, 89, 97, 135, 159],
[5, 39, 75, 102, 136, 167, 0],
[2, 54, 86, 101, 135, 164, 0],
[15, 56, 87, 108, 119, 171, 0],
[10, 44, 82, 91, 111, 144, 149],
[23, 34, 71, 94, 127, 153, 0],
[11, 49, 88, 92, 142, 157, 0],
[29, 34, 87, 97, 147, 162, 0],
[30, 50, 60, 86, 137, 142, 162],
[10, 53, 66, 84, 112, 128, 165],
[22, 57, 85, 93, 140, 159, 0],
[28, 32, 72, 103, 132, 166, 0],
[28, 29, 84, 88, 117, 143, 150],
[1, 26, 45, 80, 128, 147, 0],
[17, 27, 89, 103, 116, 153, 0],
[51, 57, 98, 163, 165, 172, 0],
[21, 37, 73, 138, 152, 169, 0],
[16, 47, 76, 130, 137, 154, 0],
[3, 24, 30, 72, 104, 139, 0],
[9, 40, 90, 106, 134, 151, 0],
[15, 58, 60, 74, 111, 150, 163],
[18, 42, 79, 144, 146, 152, 0],
[25, 38, 65, 99, 122, 160, 0],
[17, 42, 75, 129, 170, 172, 0],
]
# Each row corresponds to a codeword bit.
# The numbers indicate which three LDPC parity checks (rows in Nm) refer to the codeword bit.
# 1-origin.
kFTX_LDPC_Mn = [
[16, 45, 73],
[25, 51, 62],
[33, 58, 78],
[1, 44, 45],
[2, 7, 61],
[3, 6, 54],
[4, 35, 48],
[5, 13, 21],
[8, 56, 79],
[9, 64, 69],
[10, 19, 66],
[11, 36, 60],
[12, 37, 58],
[14, 32, 43],
[15, 63, 80],
[17, 28, 77],
[18, 74, 83],
[22, 53, 81],
[23, 30, 34],
[24, 31, 40],
[26, 41, 76],
[27, 57, 70],
[29, 49, 65],
[3, 38, 78],
[5, 39, 82],
[46, 50, 73],
[51, 52, 74],
[55, 71, 72],
[44, 67, 72],
[43, 68, 78],
[1, 32, 59],
[2, 6, 71],
[4, 16, 54],
[7, 65, 67],
[8, 30, 42],
[9, 22, 31],
[10, 18, 76],
[11, 23, 82],
[12, 28, 61],
[13, 52, 79],
[14, 50, 51],
[15, 81, 83],
[17, 29, 60],
[19, 33, 64],
[20, 26, 73],
[21, 34, 40],
[24, 27, 77],
[25, 55, 58],
[35, 53, 66],
[36, 48, 68],
[37, 46, 75],
[38, 45, 47],
[39, 57, 69],
[41, 56, 62],
[20, 49, 53],
[46, 52, 63],
[45, 70, 75],
[27, 35, 80],
[1, 15, 30],
[2, 68, 80],
[3, 36, 51],
[4, 28, 51],
[5, 31, 56],
[6, 20, 37],
[7, 40, 82],
[8, 60, 69],
[9, 10, 49],
[11, 44, 57],
[12, 39, 59],
[13, 24, 55],
[14, 21, 65],
[16, 71, 78],
[17, 30, 76],
[18, 25, 80],
[19, 61, 83],
[22, 38, 77],
[23, 41, 50],
[7, 26, 58],
[29, 32, 81],
[33, 40, 73],
[18, 34, 48],
[13, 42, 64],
[5, 26, 43],
[47, 69, 72],
[54, 55, 70],
[45, 62, 68],
[10, 63, 67],
[14, 66, 72],
[22, 60, 74],
[35, 39, 79],
[1, 46, 64],
[1, 24, 66],
[2, 5, 70],
[3, 31, 65],
[4, 49, 58],
[1, 4, 5],
[6, 60, 67],
[7, 32, 75],
[8, 48, 82],
[9, 35, 41],
[10, 39, 62],
[11, 14, 61],
[12, 71, 74],
[13, 23, 78],
[11, 35, 55],
[15, 16, 79],
[7, 9, 16],
[17, 54, 63],
[18, 50, 57],
[19, 30, 47],
[20, 64, 80],
[21, 28, 69],
[22, 25, 43],
[13, 22, 37],
[2, 47, 51],
[23, 54, 74],
[26, 34, 72],
[27, 36, 37],
[21, 36, 63],
[29, 40, 44],
[19, 26, 57],
[3, 46, 82],
[14, 15, 58],
[33, 52, 53],
[30, 43, 52],
[6, 9, 52],
[27, 33, 65],
[25, 69, 73],
[38, 55, 83],
[20, 39, 77],
[18, 29, 56],
[32, 48, 71],
[42, 51, 59],
[28, 44, 79],
[34, 60, 62],
[31, 45, 61],
[46, 68, 77],
[6, 24, 76],
[8, 10, 78],
[40, 41, 70],
[17, 50, 53],
[42, 66, 68],
[4, 22, 72],
[36, 64, 81],
[13, 29, 47],
[2, 8, 81],
[56, 67, 73],
[5, 38, 50],
[12, 38, 64],
[59, 72, 80],
[3, 26, 79],
[45, 76, 81],
[1, 65, 74],
[7, 18, 77],
[11, 56, 59],
[14, 39, 54],
[16, 37, 66],
[10, 28, 55],
[15, 60, 70],
[17, 25, 82],
[20, 30, 31],
[12, 67, 68],
[23, 75, 80],
[27, 32, 62],
[24, 69, 75],
[19, 21, 71],
[34, 53, 61],
[35, 46, 47],
[33, 59, 76],
[40, 43, 83],
[41, 42, 63],
[49, 75, 83],
[20, 44, 48],
[42, 49, 57],
]
kFTX_LDPC_Num_rows = [
7,
6,
6,
6,
7,
6,
7,
6,
6,
7,
6,
6,
7,
7,
6,
6,
6,
7,
6,
7,
6,
7,
6,
6,
6,
7,
6,
6,
6,
7,
6,
6,
6,
6,
7,
6,
6,
6,
7,
7,
6,
6,
6,
6,
7,
7,
6,
6,
6,
6,
7,
6,
6,
6,
7,
6,
6,
6,
6,
7,
6,
6,
6,
7,
6,
6,
6,
7,
7,
6,
6,
7,
6,
6,
6,
6,
6,
6,
6,
7,
6,
6,
6,
]
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