Add pseudo-random bit sequence generator to libosmcoore

These PRBS sequences are specified in ITU-T O.150.  They are typically
used as test data to be transmitted for BER (bit error rate) testing.

Change-Id: I227b6a6e86a251460ecb816afa9a7439d5fb94d1

1 files changed, 47 insertions, 0 deletions

diff --git a/tests/prbs/prbs_test.c b/tests/prbs/prbs_test.c
new file mode 100644
index 00000000..f478635b
--- /dev/null
+++ b/tests/prbs/prbs_test.c
@@ -0,0 +1,47 @@
+#include <stdio.h>
+#include <string.h>
+#include <stdlib.h>
+#include <osmocom/core/prbs.h>
+
+static void dump_bits(const ubit_t *bits, unsigned int num_bits)
+{
+	unsigned int i;
+
+	for (i = 0; i < num_bits; i++) {
+		if (bits[i])
+			fputc('1', stdout);
+		else
+			fputc('0', stdout);
+	}
+	fputc('\n',stdout);
+}
+
+static void test_prbs(const struct osmo_prbs *prbs)
+{
+	struct osmo_prbs_state st;
+	unsigned int i;
+
+	printf("Testing PRBS sequence generation '%s'\n", prbs->name);
+	osmo_prbs_state_init(&st, prbs);
+
+	/* 2 lines */
+	for (i = 0; i < 2; i++) {
+		unsigned int seq_len = (1 << prbs->len)-1;
+		ubit_t bits[seq_len];
+		memset(bits, 0, sizeof(bits));
+		osmo_prbs_get_ubits(bits, sizeof(bits), &st);
+		dump_bits(bits, sizeof(bits));
+	}
+
+	printf("\n");
+}
+
+int main(int argc, char **argv)
+{
+	test_prbs(&osmo_prbs7);
+	test_prbs(&osmo_prbs9);
+	test_prbs(&osmo_prbs11);
+	test_prbs(&osmo_prbs15);
+
+	exit(0);
+}