From 02a0c4269fa7c818c94e49a082a95c245f573664 Mon Sep 17 00:00:00 2001
From: Ahmet Inan <inan@aicodix.de>
Date: Fri, 28 Sep 2018 11:00:29 +0200
Subject: [PATCH] added regression test for the BCH reference

---
 tests/bch_regression_test.cc | 98 ++++++++++++++++++++++++++++++++++++
 1 file changed, 98 insertions(+)
 create mode 100644 tests/bch_regression_test.cc

diff --git a/tests/bch_regression_test.cc b/tests/bch_regression_test.cc
new file mode 100644
index 0000000..e7f1d48
--- /dev/null
+++ b/tests/bch_regression_test.cc
@@ -0,0 +1,98 @@
+/*
+Regression Test for the Bose Chaudhuri Hocquenghem Encoder and Decoder
+
+Copyright 2018 Ahmet Inan <inan@aicodix.de>
+*/
+
+#include <cassert>
+#include <random>
+#include <iostream>
+#include "galois_field.hh"
+#include "bose_chaudhuri_hocquenghem_encoder.hh"
+#include "bose_chaudhuri_hocquenghem_decoder.hh"
+
+template <typename ENC, typename DEC>
+void bch_reference_test(ENC *encode, DEC *decode, int trials)
+{
+	std::random_device rd;
+	std::default_random_engine generator(rd());
+	typedef std::uniform_int_distribution<typename ENC::value_type> distribution;
+	auto rnd_cnt = std::bind(distribution(0, ENC::NR), generator);
+	auto rnd_len = std::bind(distribution(1, ENC::K), generator);
+	auto rnd_val = std::bind(distribution(0, 1), generator);
+	while (--trials) {
+		int data_len = rnd_len();
+		auto rnd_pos = std::bind(distribution(0, data_len + ENC::NP - 1), generator);
+		typename ENC::value_type data[data_len], orig_data[data_len];
+		for (int i = 0; i < data_len; ++i)
+			data[i] = orig_data[i] = rnd_val();
+		typename ENC::value_type parity[ENC::NP];
+		(*encode)(reinterpret_cast<typename ENC::ValueType *>(data), reinterpret_cast<typename ENC::ValueType *>(parity), data_len);
+		for (int i = 0; i < data_len; ++i)
+			assert(data[i] == orig_data[i]);
+		typename ENC::value_type orig_parity[ENC::NP];
+		for (int i = 0; i < ENC::NP; ++i)
+			orig_parity[i] = parity[i];
+		int error_count = rnd_cnt() / 2;
+		typename ENC::value_type errors[error_count];
+		for (int i = 0; i < error_count; ++i) {
+			int pos = rnd_pos();
+			for (int j = 0; j < i; ++j) {
+				if (errors[j] == pos) {
+					pos = rnd_pos();
+					j = -1;
+				}
+			}
+			errors[i] = pos;
+			if (pos < data_len)
+				data[pos] ^= 1;
+			else
+				parity[pos-data_len] ^= 1;
+		}
+		int erasures_count = ENC::NR - 2 * error_count;
+		typename ENC::value_type erasures[erasures_count];
+		for (int i = 0; i < erasures_count; ++i) {
+			int pos = rnd_pos();
+			for (int j = 0; j < i; ++j) {
+				if (erasures[j] == pos) {
+					pos = rnd_pos();
+					j = -1;
+				}
+			}
+			erasures[i] = pos;
+			if (pos < data_len)
+				data[pos] ^= 1;
+			else
+				parity[pos-data_len] ^= 1;
+		}
+		int ret = (*decode)(reinterpret_cast<typename ENC::ValueType *>(data), reinterpret_cast<typename ENC::ValueType *>(parity), reinterpret_cast<typename ENC::IndexType *>(erasures), erasures_count, data_len);
+		assert(ret >= 0);
+		for (int i = 0; i < data_len; ++i)
+			assert(data[i] == orig_data[i]);
+		for (int i = 0; i < ENC::NP; ++i)
+			assert(parity[i] == orig_parity[i]);
+	}
+}
+
+int main()
+{
+	if (1) {
+		// NASA INTRO BCH(15, 5) T=3
+		typedef CODE::GaloisField<4, 0b10011, uint8_t> GF;
+		GF instance;
+		CODE::BoseChaudhuriHocquenghemEncoderReference<6, 1, 5, GF> encoder({0b10011, 0b11111, 0b00111});
+		CODE::BoseChaudhuriHocquenghemDecoderReference<6, 1, 5, GF> decoder;
+		bch_reference_test(&encoder, &decoder, 1000000);
+	}
+	if (1) {
+		// DVB-S2 FULL BCH(65535, 65343) T=12
+		typedef CODE::GaloisField<16, 0b10000000000101101, uint16_t> GF;
+		GF instance;
+		CODE::BoseChaudhuriHocquenghemEncoderReference<24, 1, 65343, GF> encoder({0b10000000000101101, 0b10000000101110011, 0b10000111110111101, 0b10101101001010101, 0b10001111100101111, 0b11111011110110101, 0b11010111101100101, 0b10111001101100111, 0b10000111010100001, 0b10111010110100111, 0b10011101000101101, 0b10001101011100011});
+		CODE::BoseChaudhuriHocquenghemDecoderReference<24, 1, 65343, GF> decoder;
+		bch_reference_test(&encoder, &decoder, 100);
+	}
+	std::cerr << "Bose Chaudhuri Hocquenghem regression test passed!" << std::endl;
+	return 0;
+}
+