Define the Hanning window globally once for the pitch shifter

2 files changed, 24 insertions, 11 deletions

diff --git a/Alc/effects/pshifter.c b/Alc/effects/pshifter.c
index 4597da6b..33c3e121 100644
--- a/Alc/effects/pshifter.c
+++ b/Alc/effects/pshifter.c
@@ -66,7 +66,6 @@ typedef struct ALpshifterState {
     ALfloat LastPhase[STFT_HALF_SIZE+1];
     ALfloat SumPhase[STFT_HALF_SIZE+1];
     ALfloat OutputAccum[STFT_SIZE];
-    ALfloat window[STFT_SIZE];
 
     ALcomplex FFTbuffer[STFT_SIZE];
 
@@ -89,6 +88,23 @@ DECLARE_DEFAULT_ALLOCATORS(ALpshifterState)
 DEFINE_ALEFFECTSTATE_VTABLE(ALpshifterState);
 
 
+/* Define a Hanning window, used to filter the STFT input and output. */
+alignas(16) static ALfloat HanningWindow[STFT_SIZE];
+
+static void InitHanningWindow(void)
+{
+    ALsizei i;
+
+    /* Create lookup table of the Hanning window for the desired size, i.e. STFT_SIZE */
+    for(i = 0;i < STFT_SIZE>>1;i++)
+    {
+        ALdouble val = 1.0 - cos((ALdouble)i / (ALdouble)(STFT_SIZE-1) * (M_PI*2.0));
+        HanningWindow[i] = HanningWindow[STFT_SIZE-(i+1)] = (ALfloat)val * 0.5f;
+    }
+}
+static alonce_flag HanningInitOnce = AL_ONCE_FLAG_INIT;
+
+
 /* Converts ALcomplex to ALphasor*/
 static inline ALphasor rect2polar( ALcomplex number )
 {
@@ -203,17 +219,10 @@ static inline ALvoid FFT(ALcomplex *FFTBuffer, ALsizei FFTSize, ALfloat Sign)
 
 static void ALpshifterState_Construct(ALpshifterState *state)
 {
-    ALsizei i;
-
     ALeffectState_Construct(STATIC_CAST(ALeffectState, state));
     SET_VTABLE2(ALpshifterState, ALeffectState, state);
 
-    /* Create lockup table of the Hann window for the desired size, i.e. STFT_size */
-    for ( i = 0; i < STFT_SIZE>>1 ; i++ )
-    {
-         state->window[i] = state->window[STFT_SIZE-(i+1)]
-                          = 0.5f * ( 1 - cosf(F_TAU*(ALfloat)i/(ALfloat)(STFT_SIZE-1)));
-    }
+    alcall_once(&HanningInitOnce, InitHanningWindow);
 }
 
 static ALvoid ALpshifterState_Destruct(ALpshifterState *state)
@@ -285,7 +294,7 @@ static ALvoid ALpshifterState_process(ALpshifterState *state, ALsizei SamplesToD
         /* Real signal windowing and store in FFTbuffer */
         for(k = 0;k < STFT_SIZE;k++)
         {
-            state->FFTbuffer[k].Real = state->InFIFO[k] * state->window[k];
+            state->FFTbuffer[k].Real = state->InFIFO[k] * HanningWindow[k];
             state->FFTbuffer[k].Imag = 0.0f;
         }
 
@@ -374,7 +383,7 @@ static ALvoid ALpshifterState_process(ALpshifterState *state, ALsizei SamplesToD
 
         /* Windowing and add to output */
         for(k = 0;k < STFT_SIZE;k++)
-            state->OutputAccum[k] += 2.0f * state->window[k]*state->FFTbuffer[k].Real /
+            state->OutputAccum[k] += 2.0f * HanningWindow[k]*state->FFTbuffer[k].Real /
                                      (STFT_HALF_SIZE * OVERSAMP);
 
         /* Shift accumulator, input & output FIFO */
diff --git a/common/math_defs.h b/common/math_defs.h
index 428f5181..8ce93d0a 100644
--- a/common/math_defs.h
+++ b/common/math_defs.h
@@ -6,6 +6,10 @@
 #include <float.h>
 #endif
 
+#ifndef M_PI
+#define M_PI (3.14159265358979323846)
+#endif
+
 #define F_PI    (3.14159265358979323846f)
 #define F_PI_2  (1.57079632679489661923f)
 #define F_TAU   (6.28318530717958647692f)