Use acosf when available

Alc/ALu.c

@@ -49,6 +49,12 @@ typedef long long ALint64;
 #define aluSqrt(x) ((ALfloat)sqrt((double)(x)))
 #endif
 
+#ifdef HAVE_ACOSF
+#define aluAcos(x) ((ALfloat)acosf((float)(x)))
+#else
+#define aluAcos(x) ((ALfloat)acos((double)(x)))
+#endif
+
 // fixes for mingw32.
 #if defined(max) && !defined(__max)
 #define __max max
@@ -390,7 +396,8 @@ static ALvoid CalcSourceParams(ALCcontext *ALContext, ALsource *ALSource,
         SourceToListener[2] = -Position[2];
         aluNormalize(Direction);
         aluNormalize(SourceToListener);
-        Angle = (ALfloat)(180.0*acos(aluDotproduct(Direction,SourceToListener))/3.141592654f);
+        Angle = aluAcos(aluDotproduct(Direction,SourceToListener)) * 180.0f /
+                3.141592654f;
         if(Angle >= InnerAngle && Angle <= OuterAngle)
         {
             ALfloat scale = (Angle-InnerAngle) / (OuterAngle-InnerAngle);

CMakeLists.txt

@@ -101,7 +101,8 @@ ENDIF()
 
 
 CHECK_LIBRARY_EXISTS(m  sqrtf  "" HAVE_SQRTF)
-IF(HAVE_SQRTF)
+CHECK_LIBRARY_EXISTS(m  acosf  "" HAVE_ACOSF)
+IF(HAVE_SQRTF OR HAVE_ACOSF)
     SET(EXTRA_LIBS m ${EXTRA_LIBS})
 ENDIF()
 CHECK_FUNCTION_EXISTS(strtof HAVE_STRTOF)

config.h.in

@@ -19,6 +19,9 @@
 /* Define if we have the sqrtf function */
 #cmakedefine HAVE_SQRTF
 
+/* Define if we have the acosf function */
+#cmakedefine HAVE_ACOSF
+
 /* Define if we have the strtof function */
 #cmakedefine HAVE_STRTOF