NMT: Implement Hagelbarger Code

This will correct burst errors of received messages. If the message
is too corrupted, it will be ignored, because some element may not
match then. The digits and line signals are checked for consistency,
since they are repeated serveral times in a message.

2 files changed, 38 insertions, 1 deletions

diff --git a/src/test/Makefile.am b/src/test/Makefile.am
index 852c235..dbe6c73 100644
--- a/src/test/Makefile.am
+++ b/src/test/Makefile.am
@@ -7,7 +7,8 @@ noinst_PROGRAMS = \
 	test_emphasis \
 	test_dms \
 	test_sms \
-	test_performance
+	test_performance \
+	test_hagelbarger
 
 test_filter_SOURCES = test_filter.c dummy.c
 
@@ -77,3 +78,10 @@ test_performance_LDADD = \
 	$(SOAPY_LIBS) \
 	-lm
 
+test_hagelbarger_SOURCES = \
+	$(top_builddir)/src/nmt/hagelbarger.c \
+	test_hagelbarger.c
+
+test_hagelbarger_LDADD = \
+	$(COMMON_LA)
+
diff --git a/src/test/test_hagelbarger.c b/src/test/test_hagelbarger.c
new file mode 100644
index 0000000..d4117e3
--- /dev/null
+++ b/src/test/test_hagelbarger.c
@@ -0,0 +1,29 @@
+#include "stdio.h"
+#include "stdint.h"
+#include "string.h"
+#include "../nmt/hagelbarger.h"
+
+int main(void)
+{
+	uint8_t message[9] = "JollyRog", code[20];
+
+	printf("Message: %s\n", message);
+
+	/* clean tail at code bit 72 and above */
+	memset(code, 0, sizeof(code));
+
+	/* encode message */
+	hagelbarger_encode(message, code, 72);
+
+	/* corrupt data */
+	code[0] ^= 0xfc;
+	code[3] ^= 0xfc;
+	code[7] ^= 0xfc;
+
+	/* decode */
+	hagelbarger_decode(code, message, 64);
+	printf("Decoded: %s (must be the same as above)\n", message);
+
+	return 0;
+}
+