Add TickCounter for measuring performance

libctru/include/3ds/os.h

@@ -3,6 +3,7 @@
  * @brief OS related stuff.
  */
 #pragma once
+#include "svc.h"
 
 /// Packs a system version from its components.
 #define SYSTEM_VERSION(major, minor, revision) \
@@ -26,6 +27,13 @@ typedef enum
 	MEMREGION_BASE = 3,        ///< BASE memory.
 } MemRegion;
 
+/// Tick counter.
+typedef struct
+{
+	u64 elapsed;   ///< Elapsed CPU ticks between measurements.
+	u64 reference; ///< Point in time used as reference.
+} TickCounter;
+
 /// OS_VersionBin. Format of the system version: "<major>.<minor>.<build>-<nupver><region>"
 typedef struct
 {
@@ -124,6 +132,33 @@ static inline s64 osGetMemRegionFree(MemRegion region)
  */
 u64 osGetTime(void);
 
+/**
+ * @brief Starts a tick counter.
+ * @param cnt The tick counter.
+ */
+static inline void osTickCounterStart(TickCounter* cnt)
+{
+	cnt->reference = svcGetSystemTick();
+}
+
+/**
+ * @brief Updates the elapsed time in a tick counter.
+ * @param cnt The tick counter.
+ */
+static inline void osTickCounterUpdate(TickCounter* cnt)
+{
+	u64 now = svcGetSystemTick();
+	cnt->elapsed = now - cnt->reference;
+	cnt->reference = now;
+}
+
+/**
+ * @brief Reads the elapsed time in a tick counter.
+ * @param cnt The tick counter.
+ * @return The number of milliseconds elapsed.
+ */
+double osTickCounterRead(TickCounter* cnt);
+
 /**
  * @brief Gets the current Wifi signal strength.
  * @return The current Wifi signal strength.

libctru/source/os.c

@@ -115,6 +115,12 @@ u64 osGetTime(void) {
 	return dt.date_time + (u32)(u64_to_double(delta)/TICKS_PER_MSEC);
 }
 
+//---------------------------------------------------------------------------------
+double osTickCounterRead(TickCounter* cnt) {
+//---------------------------------------------------------------------------------
+	return u64_to_double(cnt->elapsed) / TICKS_PER_MSEC;
+}
+
 //---------------------------------------------------------------------------------
 const char* osStrError(u32 error) {
 //---------------------------------------------------------------------------------