uhd: math: Add interpolation.hpp

- Moves linear_interp from cal to utils
- Moves the interp_mode enum class to interpolation.hpp
- Adds three interpolation methods for maps: at_interpolate_1d(),
  at_nearest(), at_lin_interp()
- Adds unit tests

4 files changed, 37 insertions, 10 deletions

diff --git a/host/tests/CMakeLists.txt b/host/tests/CMakeLists.txt
index 3665a9d17..33bcdb734 100644
--- a/host/tests/CMakeLists.txt
+++ b/host/tests/CMakeLists.txt
@@ -36,6 +36,7 @@ set(test_sources
     fp_compare_delta_test.cpp
     fp_compare_epsilon_test.cpp
     gain_group_test.cpp
+    interpolation_test.cpp
     isatty_test.cpp
     log_test.cpp
     math_test.cpp
diff --git a/host/tests/cal_data_iq_test.cpp b/host/tests/cal_data_iq_test.cpp
index 97b35a331..523a4310e 100644
--- a/host/tests/cal_data_iq_test.cpp
+++ b/host/tests/cal_data_iq_test.cpp
@@ -10,6 +10,7 @@
 #include <iostream>
 
 using namespace uhd::usrp::cal;
+using namespace uhd::math;
 
 BOOST_AUTO_TEST_CASE(test_iq_cal_api)
 {
diff --git a/host/tests/interpolation_test.cpp b/host/tests/interpolation_test.cpp
new file mode 100644
index 000000000..b3314c34a
--- /dev/null
+++ b/host/tests/interpolation_test.cpp
@@ -0,0 +1,35 @@
+//
+// Copyright 2020 Ettus Research, a National Instruments Brand
+//
+// SPDX-License-Identifier: GPL-3.0-or-later
+//
+
+#include <uhdlib/utils/interpolation.hpp>
+#include <boost/test/unit_test.hpp>
+
+BOOST_AUTO_TEST_CASE(test_interp)
+{
+    const double x0 = 1.0, x1 = 2.0;
+    const double y0 = 2.0, y1 = 4.0;
+    const double x     = 1.5;
+    const double y_exp = 3.0;
+
+    BOOST_CHECK_EQUAL(uhd::math::linear_interp<double>(x, x0, y0, x1, y1), y_exp);
+}
+
+BOOST_AUTO_TEST_CASE(test_map_interp)
+{
+    using namespace uhd::math;
+    std::map<double, double> test_data{{1.0, 1.0}, {2.0, 2.0}, {3.0, 3.0}};
+
+    BOOST_CHECK_EQUAL(at_nearest(test_data, 1.1), 1.0);
+    BOOST_CHECK_EQUAL(at_nearest(test_data, 1.9), 2.0);
+    BOOST_CHECK_EQUAL(at_nearest(test_data, 2.1), 2.0);
+    BOOST_CHECK_EQUAL(at_nearest(test_data, 1e9), 3.0);
+
+    BOOST_CHECK_CLOSE(at_lin_interp(test_data, 1.5), 1.5, 1e-6);
+    BOOST_CHECK_EQUAL(at_lin_interp(test_data, 0.1), 1.0);
+    BOOST_CHECK_EQUAL(at_lin_interp(test_data, 2.0), 2.0);
+    BOOST_CHECK_EQUAL(at_lin_interp(test_data, 137.0), 3.0);
+}
+
diff --git a/host/tests/math_test.cpp b/host/tests/math_test.cpp
index bff6fc16f..c1b6793bb 100644
--- a/host/tests/math_test.cpp
+++ b/host/tests/math_test.cpp
@@ -17,13 +17,3 @@ BOOST_AUTO_TEST_CASE(test_gcd)
 {
     BOOST_CHECK_EQUAL(uhd::math::gcd<int>(6, 15), 3);
 }
-
-BOOST_AUTO_TEST_CASE(test_interp)
-{
-    const double x0 = 1.0, x1 = 2.0;
-    const double y0 = 2.0, y1 = 4.0;
-    const double x     = 1.5;
-    const double y_exp = 3.0;
-
-    BOOST_CHECK_EQUAL(uhd::math::linear_interp<double>(x, x0, y0, x1, y1), y_exp);
-}