From 7f9761afb694116b33d21a012502c5895cd6d10f Mon Sep 17 00:00:00 2001
From: twinaphex <libretro@gmail.com>
Date: Sun, 13 Sep 2015 03:43:59 +0200
Subject: [PATCH] Create kaiser_window_function/lanzcos_window_function

---
 audio/drivers_resampler/sinc.c    |  4 ++--
 libretro-common/include/filters.h | 10 ++++++++++
 2 files changed, 12 insertions(+), 2 deletions(-)

diff --git a/audio/drivers_resampler/sinc.c b/audio/drivers_resampler/sinc.c
index 8f157700dc..87c54ec47d 100644
--- a/audio/drivers_resampler/sinc.c
+++ b/audio/drivers_resampler/sinc.c
@@ -118,9 +118,9 @@ typedef struct rarch_sinc_resampler
 } rarch_sinc_resampler_t;
 
 #if defined(SINC_WINDOW_LANCZOS)
-#define window_function(idx)  (sinc(M_PI * (idx)))
+#define window_function(idx)  (lanzcos_window_function(idx))
 #elif defined(SINC_WINDOW_KAISER)
-#define window_function(idx) (besseli0(SINC_WINDOW_KAISER_BETA * sqrt(1 - (idx) * (idx))))
+#define window_function(idx)  (kaiser_window_function(idx, SINC_WINDOW_KAISER_BETA))
 #else
 #error "No SINC window function defined."
 #endif
diff --git a/libretro-common/include/filters.h b/libretro-common/include/filters.h
index 2933180bfe..499e14dcc1 100644
--- a/libretro-common/include/filters.h
+++ b/libretro-common/include/filters.h
@@ -60,4 +60,14 @@ static INLINE double besseli0(double x)
    return sum;
 }
 
+static INLINE double kaiser_window_function(double index, double beta)
+{
+   return besseli0(beta * sqrtf(1 - index * index));
+}
+
+static INLINE double lanzcos_window_function(double index)
+{
+   return sinc(M_PI * index);
+}
+
 #endif