Add glfwGetTimerValue and glfwGetTimerFrequency

This adds raw timer access to the public API and builds the floating-point time functions on top. It also makes the GLFWuint64 type public.
Looking-Glass · Mar 6, 2016 · 31f67dd · 31f67dd
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Showing 14 changed files with 148 additions and 96 deletions.
diff --git a/README.md b/README.md
@@ -83,6 +83,8 @@ does not find Doxygen, the documentation will not be generated.
    absolute and relative window size limits
  - Added `glfwGetKeyName` for querying the layout-specific name of printable
    keys
+ - Added `glfwGetTimerValue` and `glfwGetTimerFrequency` for raw timer access
+ - Added `GLFWuint64` for platform-independent 64-bit unsigned values
  - Added `GLFW_NO_API` for creating window without contexts
  - Added `GLFW_CONTEXT_NO_ERROR` context hint for `GL_KHR_no_error` support
  - Added `GLFW_INCLUDE_VULKAN` for including the Vulkan header

diff --git a/docs/input.dox b/docs/input.dox
@@ -554,6 +554,21 @@ glfwSetTime(4.0);
 
 This sets the timer to the specified time, in seconds.
 
+You can also access the raw timer value, in 1&nbsp;/&nbsp;frequency seconds,
+with @ref glfwGetTimerValue.
+
+@code
+GLFWuint64 value = glfwGetTimerValue();
+@endcode
+
+The frequency of the raw timer varies depending on what time sources are
+available on the machine.  You can query its frequency, in Hz, with @ref
+glfwGetTimerFrequency.
+
+@code
+GLFWuint64 freqency = glfwGetTimerFrequency();
+@endcode
+
 
 @section clipboard Clipboard input and output
 

diff --git a/docs/news.dox b/docs/news.dox
@@ -37,6 +37,12 @@ GLFW now supports window maximization with @ref glfwMaximizeWindow and the
 GLFW now supports giving windows input focus with @ref glfwFocusWindow.
 
 
+@subsection news_32_timer Raw timer access
+
+GLFW now supports raw timer values with @ref glfwGetTimerValue and @ref
+glfwGetTimerFrequency.
+
+
 @section news_31 New features in 3.1
 
 These are the release highlights.  For a full list of changes see the

diff --git a/include/GLFW/glfw3.h b/include/GLFW/glfw3.h
@@ -728,6 +728,19 @@ extern "C" {
  * GLFW API types
  *************************************************************************/
 
+/*! @brief 64-bit unsigned integer.
+ *
+ *  64-bit unsigned integer.
+ *
+ *  @since Added in version 3.2.
+ */
+#if defined(_MSC_VER) && (_MSC_VER < 1600)
+typedef unsigned __int64 GLFWuint64;
+#else
+ #include <stdint.h>
+typedef uint64_t GLFWuint64;
+#endif
+
 /*! @brief Client API function pointer type.
  *
  *  Generic function pointer used for returning client API function pointers
@@ -3557,6 +3570,47 @@ GLFWAPI double glfwGetTime(void);
  */
 GLFWAPI void glfwSetTime(double time);
 
+/*! @brief Returns the current value of the raw timer.
+ *
+ *  This function returns the current value of the raw timer.  To get its
+ *  frequency, call @ref glfwGetTimerFrequency.
+ *
+ *  @return The value of the timer, or zero if an 
+ *  [error](@ref error_handling) occurred.
+ *
+ *  @errors Possible errors include @ref GLFW_NOT_INITIALIZED and @ref
+ *  GLFW_INVALID_VALUE.
+ *
+ *  @thread_safety This function may be called from any thread.
+ *
+ *  @sa @ref time
+ *  @sa glfwGetTimerFrequency
+ *
+ *  @since Added in version 3.2.
+ *
+ *  @ingroup input
+ */
+GLFWAPI GLFWuint64 glfwGetTimerValue(void);
+
+/*! @brief Returns the frequency, in Hz, of the raw timer.
+ *
+ *  @return The frequency of the timer, in Hz, or zero if an
+ *  [error](@ref error_handling) occurred.
+ *
+ *  @errors Possible errors include @ref GLFW_NOT_INITIALIZED and @ref
+ *  GLFW_INVALID_VALUE.
+ *
+ *  @thread_safety This function may be called from any thread.
+ *
+ *  @sa @ref time
+ *  @sa glfwGetTimerValue
+ *
+ *  @since Added in version 3.2.
+ *
+ *  @ingroup input
+ */
+GLFWAPI GLFWuint64 glfwGetTimerFrequency(void);
+
 /*! @brief Makes the context of the specified window current for the calling
  *  thread.
  *

diff --git a/src/cocoa_platform.h b/src/cocoa_platform.h
@@ -118,8 +118,7 @@ typedef struct _GLFWcursorNS
 //
 typedef struct _GLFWtimeNS
 {
-    double          base;
-    double          resolution;
+    GLFWuint64      frequency;
 
 } _GLFWtimeNS;
 

diff --git a/src/cocoa_time.c b/src/cocoa_time.c
@@ -29,14 +29,6 @@
 #include <mach/mach_time.h>
 
 
-// Return raw time
-//
-static uint64_t getRawTime(void)
-{
-    return mach_absolute_time();
-}
-
-
 //////////////////////////////////////////////////////////////////////////
 //////                       GLFW internal API                      //////
 //////////////////////////////////////////////////////////////////////////
@@ -48,24 +40,21 @@ void _glfwInitTimerNS(void)
     mach_timebase_info_data_t info;
     mach_timebase_info(&info);
 
-    _glfw.ns_time.resolution = (double) info.numer / (info.denom * 1.0e9);
-    _glfw.ns_time.base = getRawTime();
+    _glfw.ns_time.frequency = (info.denom * 1e9) / info.numer;
 }
 
 
 //////////////////////////////////////////////////////////////////////////
 //////                       GLFW platform API                      //////
 //////////////////////////////////////////////////////////////////////////
 
-double _glfwPlatformGetTime(void)
+GLFWuint64 _glfwPlatformGetTimerValue(void)
 {
-    return (double) (getRawTime() - _glfw.ns_time.base) *
-        _glfw.ns_time.resolution;
+    return mach_absolute_time();
 }
 
-void _glfwPlatformSetTime(double time)
+GLFWuint64 _glfwPlatformGetTimerFrequency(void)
 {
-    _glfw.ns_time.base = getRawTime() -
-        (uint64_t) (time / _glfw.ns_time.resolution);
+    return _glfw.ns_time.frequency;
 }
 
diff --git a/src/init.c b/src/init.c
@@ -135,6 +135,8 @@ GLFWAPI int glfwInit(void)
     _glfw.monitors = _glfwPlatformGetMonitors(&_glfw.monitorCount);
     _glfwInitialized = GLFW_TRUE;
 
+    _glfw.timerOffset = _glfwPlatformGetTimerValue();
+
     // Not all window hints have zero as their default value
     glfwDefaultWindowHints();
 

diff --git a/src/input.c b/src/input.c
@@ -645,7 +645,8 @@ GLFWAPI const char* glfwGetClipboardString(GLFWwindow* handle)
 GLFWAPI double glfwGetTime(void)
 {
     _GLFW_REQUIRE_INIT_OR_RETURN(0.0);
-    return _glfwPlatformGetTime();
+    return (double) (_glfwPlatformGetTimerValue() - _glfw.timerOffset) /
+        _glfwPlatformGetTimerFrequency();
 }
 
 GLFWAPI void glfwSetTime(double time)
@@ -658,6 +659,19 @@ GLFWAPI void glfwSetTime(double time)
         return;
     }
 
-    _glfwPlatformSetTime(time);
+    _glfw.timerOffset = _glfwPlatformGetTimerValue() -
+        (GLFWuint64) (time * _glfwPlatformGetTimerFrequency());
+}
+
+GLFWAPI GLFWuint64 glfwGetTimerValue(void)
+{
+    _GLFW_REQUIRE_INIT_OR_RETURN(0);
+    return _glfwPlatformGetTimerValue();
+}
+
+GLFWAPI GLFWuint64 glfwGetTimerFrequency(void)
+{
+    _GLFW_REQUIRE_INIT_OR_RETURN(0);
+    return _glfwPlatformGetTimerFrequency();
 }
 
diff --git a/src/internal.h b/src/internal.h
@@ -47,13 +47,6 @@
 #define GLFW_INCLUDE_NONE
 #include "../include/GLFW/glfw3.h"
 
-#if defined(_MSC_VER) && (_MSC_VER < 1600)
-typedef unsigned __int64 GLFWuint64;
-#else
- #include <stdint.h>
-typedef uint64_t GLFWuint64;
-#endif
-
 typedef int GLFWbool;
 
 typedef struct _GLFWwndconfig   _GLFWwndconfig;
@@ -432,6 +425,8 @@ struct _GLFWlibrary
     _GLFWmonitor**      monitors;
     int                 monitorCount;
 
+    GLFWuint64          timerOffset;
+
     struct {
         GLFWbool        available;
         void*           handle;
@@ -596,15 +591,15 @@ const unsigned char* _glfwPlatformGetJoystickButtons(int joy, int* count);
  */
 const char* _glfwPlatformGetJoystickName(int joy);
 
-/*! @copydoc glfwGetTime
+/*! @copydoc glfwGetTimerValue
  *  @ingroup platform
  */
-double _glfwPlatformGetTime(void);
+GLFWuint64 _glfwPlatformGetTimerValue(void);
 
-/*! @copydoc glfwSetTime
+/*! @copydoc glfwGetTimerFrequency
  *  @ingroup platform
  */
-void _glfwPlatformSetTime(double time);
+GLFWuint64 _glfwPlatformGetTimerFrequency(void);
 
 /*! @ingroup platform
  */

diff --git a/src/posix_time.c b/src/posix_time.c
@@ -30,28 +30,6 @@
 #include <sys/time.h>
 #include <time.h>
 
-// Return raw time
-//
-static uint64_t getRawTime(void)
-{
-#if defined(CLOCK_MONOTONIC)
-    if (_glfw.posix_time.monotonic)
-    {
-        struct timespec ts;
-
-        clock_gettime(CLOCK_MONOTONIC, &ts);
-        return (uint64_t) ts.tv_sec * (uint64_t) 1000000000 + (uint64_t) ts.tv_nsec;
-    }
-    else
-#endif
-    {
-        struct timeval tv;
-
-        gettimeofday(&tv, NULL);
-        return (uint64_t) tv.tv_sec * (uint64_t) 1000000 + (uint64_t) tv.tv_usec;
-    }
-}
-
 
 //////////////////////////////////////////////////////////////////////////
 //////                       GLFW internal API                      //////
@@ -67,31 +45,41 @@ void _glfwInitTimerPOSIX(void)
     if (clock_gettime(CLOCK_MONOTONIC, &ts) == 0)
     {
         _glfw.posix_time.monotonic = GLFW_TRUE;
-        _glfw.posix_time.resolution = 1e-9;
+        _glfw.posix_time.frequency = 1000000000;
     }
     else
 #endif
     {
-        _glfw.posix_time.resolution = 1e-6;
+        _glfw.posix_time.monotonic = GLFW_FALSE;
+        _glfw.posix_time.frequency = 1000000;
     }
-
-    _glfw.posix_time.base = getRawTime();
 }
 
 
 //////////////////////////////////////////////////////////////////////////
 //////                       GLFW platform API                      //////
 //////////////////////////////////////////////////////////////////////////
 
-double _glfwPlatformGetTime(void)
+GLFWuint64 _glfwPlatformGetTimerValue(void)
 {
-    return (double) (getRawTime() - _glfw.posix_time.base) *
-        _glfw.posix_time.resolution;
+#if defined(CLOCK_MONOTONIC)
+    if (_glfw.posix_time.monotonic)
+    {
+        struct timespec ts;
+        clock_gettime(CLOCK_MONOTONIC, &ts);
+        return (uint64_t) ts.tv_sec * (uint64_t) 1000000000 + (uint64_t) ts.tv_nsec;
+    }
+    else
+#endif
+    {
+        struct timeval tv;
+        gettimeofday(&tv, NULL);
+        return (uint64_t) tv.tv_sec * (uint64_t) 1000000 + (uint64_t) tv.tv_usec;
+    }
 }
 
-void _glfwPlatformSetTime(double time)
+GLFWuint64 _glfwPlatformGetTimerFrequency(void)
 {
-    _glfw.posix_time.base = getRawTime() -
-        (uint64_t) (time / _glfw.posix_time.resolution);
+    return _glfw.posix_time.frequency;
 }
 
diff --git a/src/posix_time.h b/src/posix_time.h
@@ -38,8 +38,7 @@
 typedef struct _GLFWtimePOSIX
 {
     GLFWbool    monotonic;
-    double      resolution;
-    uint64_t    base;
+    GLFWuint64  frequency;
 
 } _GLFWtimePOSIX;
 

diff --git a/src/win32_platform.h b/src/win32_platform.h
@@ -277,8 +277,7 @@ typedef struct _GLFWcursorWin32
 typedef struct _GLFWtimeWin32
 {
     GLFWbool            hasPC;
-    double              resolution;
-    unsigned __int64    base;
+    GLFWuint64          frequency;
 
 } _GLFWtimeWin32;