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, 25 insertions, 0 deletions

diff --git a/include/osmocom/core/prbs.h b/include/osmocom/core/prbs.h
new file mode 100644
index 00000000..aaca17d9
--- /dev/null
+++ b/include/osmocom/core/prbs.h
@@ -0,0 +1,25 @@
+#pragma once
+#include <stdint.h>
+#include <osmocom/core/bits.h>
+
+/*! \brief definition of a PRBS sequence */
+struct osmo_prbs {
+	const char *name;	/*!< human-readable name */
+	unsigned int len;	/*!< length in bits */
+	uint64_t coeff;		/*!< coefficients */
+};
+
+/*! \brief state of a given PRBS sequence generator */
+struct osmo_prbs_state {
+	const struct osmo_prbs *prbs;
+	uint64_t state;
+};
+
+extern const struct osmo_prbs osmo_prbs7;
+extern const struct osmo_prbs osmo_prbs9;
+extern const struct osmo_prbs osmo_prbs11;
+extern const struct osmo_prbs osmo_prbs15;
+
+void osmo_prbs_state_init(struct osmo_prbs_state *st, const struct osmo_prbs *prbs);
+ubit_t osmo_prbs_get_ubit(struct osmo_prbs_state *state);
+int osmo_prbs_get_ubits(ubit_t *out, unsigned int out_len, struct osmo_prbs_state *state);