Add fsn lib to simplify frame/slot handling

Refactor existing code, and harmonize interface. Add a couple of tests.

Signed-off-by: Robert Schmidt <robert.schmidt@openairinterface.org>

common/utils/tests/test_fsn.cpp

@@ -0,0 +1,84 @@
+/*
+ * SPDX-License-Identifier: LicenseRef-CSSL-1.0
+ */
+
+#include <gtest/gtest.h>
+extern "C" {
+#include "fsn.h"
+}
+
+TEST(fsn, test_mu0_fsn_add) {
+  fsn_t current = {123, 5, 0};
+  fsn_t next = current;
+
+  next = fsn_add_delta(next, 12);
+  EXPECT_EQ(next.f, 124);
+  EXPECT_EQ(next.s, 7);
+  EXPECT_EQ(next.mu, 0);
+
+  next = fsn_add_delta(next, 10);
+  EXPECT_EQ(next.f, 125);
+  EXPECT_EQ(next.s, 7);
+  EXPECT_EQ(next.mu, 0);
+
+  next = fsn_add_delta(next, 10 * 1024);
+  EXPECT_EQ(next.f, 125);
+  EXPECT_EQ(next.s, 7);
+  EXPECT_EQ(next.mu, 0);
+}
+
+TEST(fsn, test_mu0_get_diff) {
+  fsn_t current = {123, 5, 0};
+  fsn_t next = fsn_add_delta(current, 12);
+  int diff;
+
+  diff = fsn_get_diff(current, next);
+  EXPECT_EQ(diff, -12);
+
+  diff = fsn_get_diff(next, current);
+  EXPECT_EQ(diff, 12);
+}
+
+TEST(fsn, test_mu0_get_max) {
+  fsn_t current = {123, 5, 0};
+  fsn_t next = {125, 7, 0};
+
+  fsn_t max = fsn_get_max(current, next);
+  EXPECT_EQ(max.f, next.f);
+  EXPECT_EQ(max.s, next.s);
+  EXPECT_EQ(max.mu, next.mu);
+}
+
+TEST(fsn, test_mu0_equal) {
+  fsn_t a = {123, 5, 0};
+  fsn_t b = a;
+  fsn_t c = {123, 6, 0};
+
+  EXPECT_TRUE(fsn_equal(a, b));
+  EXPECT_FALSE(fsn_equal(a, c));
+}
+
+TEST(fsn, test_mu0_in_the_past) {
+  fsn_t a = {0, 0, 0};
+  fsn_t n = {100, 9, 0};
+  fsn_t b_bef = {511, 9, 0};
+  fsn_t b_ex = {512, 0, 0};
+  fsn_t b_aft = {512, 1, 0};
+
+  // a is in the past of n
+  EXPECT_TRUE(fsn_in_the_past(a, n));
+  // similarly, a is in the past of b_bef
+  EXPECT_TRUE(fsn_in_the_past(a, b_bef));
+  // difference "to both sides" is 512 frames, so we consider a still in the
+  // past of b_ex
+  EXPECT_TRUE(fsn_in_the_past(a, b_ex));
+  // (b_aft - a) < (a - b_aft) => b_aft is in the past of a because of
+  // wrap-around
+  EXPECT_TRUE(fsn_in_the_past(b_aft, a));
+}
+
+int main(int argc, char** argv)
+{
+  testing::InitGoogleTest(&argc, argv);
+  return RUN_ALL_TESTS();
+}