From 513664a0e34a0ef6329802ce2351418c828c5b69 Mon Sep 17 00:00:00 2001
From: Ahmet Inan <xdsopl@gmail.com>
Date: Sat, 16 Dec 2023 08:30:47 +0100
Subject: [PATCH] shuffle the code bits

---
 decode.cc | 3 +++
 encode.cc | 3 +++
 2 files changed, 6 insertions(+)

diff --git a/decode.cc b/decode.cc
index 9de7d57..b8d7ed6 100644
--- a/decode.cc
+++ b/decode.cc
@@ -14,6 +14,7 @@ namespace DSP { using std::abs; using std::min; using std::cos; using std::sin;
 #include "xorshift.hh"
 #include "trigger.hh"
 #include "complex.hh"
+#include "permute.hh"
 #include "decibel.hh"
 #include "blockdc.hh"
 #include "hilbert.hh"
@@ -204,6 +205,7 @@ struct Decoder
 	CODE::OrderedStatisticsDecoder<255, 71, 4> osddec;
 	CODE::PolarEncoder<mesg_type> polarenc;
 	CODE::PolarListDecoder<mesg_type, code_order> polardec;
+	CODE::ReverseFisherYatesShuffle<code_len> shuffle;
 	int8_t genmat[255*71];
 	mesg_type mesg[max_bits], mess[code_len];
 	code_type code[code_len];
@@ -431,6 +433,7 @@ struct Decoder
 		*len = data_bits / 8;
 		crc_bits = data_bits + 32;
 		CODE::PolarHelper<mesg_type>::PATH metric[mesg_type::SIZE];
+		shuffle(code);
 		polardec(metric, mesg, code, frozen_bits, code_order);
 		systematic();
 		int order[mesg_type::SIZE];
diff --git a/encode.cc b/encode.cc
index 4ddc6e9..919cc60 100644
--- a/encode.cc
+++ b/encode.cc
@@ -9,6 +9,7 @@ Copyright 2021 Ahmet Inan <inan@aicodix.de>
 #include <cmath>
 #include "xorshift.hh"
 #include "complex.hh"
+#include "permute.hh"
 #include "utils.hh"
 #include "bitman.hh"
 #include "decibel.hh"
@@ -48,6 +49,7 @@ struct Encoder
 	CODE::CRC<uint32_t> crc1;
 	CODE::BoseChaudhuriHocquenghemEncoder<255, 71> bchenc;
 	CODE::PolarSysEnc<code_type> polarenc;
+	CODE::FisherYatesShuffle<code_len> shuffle;
 	code_type code[code_len], mesg[max_bits];
 	cmplx fdom[symbol_len];
 	cmplx tdom[symbol_len];
@@ -241,6 +243,7 @@ struct Encoder
 			for (int i = 0; i < 32; ++i)
 				mesg[i+data_bits] = nrz((crc1()>>i)&1);
 			polarenc(code, mesg, frozen_bits, code_order);
+			shuffle(code);
 			for (int i = 0; i < cons_cols; ++i)
 				prev[i] = fdom[bin(i+code_off)];
 			for (int j = 0; j < cons_rows; ++j) {