test_utils: implement performance timer

tools/unit-test-app/components/test_utils/include/ccomp_timer.h

@@ -0,0 +1,54 @@
+// Copyright 2019 Espressif Systems (Shanghai) PTE LTD
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#pragma once
+
+#include <stdint.h>
+
+#include "esp_err.h"
+
+/**
+ * @brief Start the timer on the current core.
+ *
+ * @return
+ *  - ESP_OK: Success
+ *  - ESP_ERR_INVALID_STATE: The timer has already been started previously.
+ *  - Others: Fail
+ */
+esp_err_t ccomp_timer_start(void);
+
+/**
+ * @brief Stop the timer on the current core.
+ * 
+ * @note Returns -1 if an error has occured and stopping the timer failed.
+ *
+ * @return The time elapsed from the last ccomp_timer_start call on the current
+ *         core.
+ */
+int64_t ccomp_timer_stop(void);
+
+/**
+ * Return the current timer value on the current core without stopping the timer.
+ *
+ * @note Returns -1 if an error has occured and stopping the timer failed.
+ * 
+ * @note If called while timer is active i.e. between ccomp_timer_start and ccomp_timer_stop,
+ * this function returns the elapsed time from ccomp_timer_start. Once ccomp_timer_stop 
+ * has been called, the timer becomes inactive and stops keeping time. As a result, if this function gets
+ * called after esp_cccomp_timer_stop, this function will return the same value as when the timer was stopped.
+ *
+ * @return The elapsed time from the last ccomp_timer_start call on the current 
+ *          core.
+ */
+int64_t ccomp_timer_get_time(void);