Ignore generated binaries.

[simgear.git] / simgear / math / fastmath.hxx

diff --git a/simgear/math/fastmath.hxx b/simgear/math/fastmath.hxx
index 6ebecd3f2a4f2a3537b461dee67db470c0f6e033..2408f51e91017db5d2689221d79fd3f7fe114f4f 100644 (file)
--- a/simgear/math/fastmath.hxx
+++ b/simgear/math/fastmath.hxx
@@ -25,31 +25,47 @@
 # error This library requires C++
 #endif
 
-#ifdef _MSC_VER
-#define  _USE_MATH_DEFINES
-#endif
 #include <math.h>
 
 
 double fast_exp(double val);
+double fast_exp2(const double val);
+
+float fast_pow(const float val1, const float val2);
+float fast_log2(const float cal);
+float fast_root(const float f, const int n);
+
+float _fast_pow2(const float cal);
+float _fast_log2(const float val);
+
+float fast_sin(const float val);
+float fast_cos(const float val);
+float fast_tan(const float val);
+float fast_asin(const float val);
+float fast_acos(const float val);
+float fast_atan(const float val);
 
 void fast_BSL(float &x, register unsigned long shiftAmount);
 void fast_BSR(float &x, register unsigned long shiftAmount);
 
+
 inline float fast_log2 (float val)
 {
-   int * const    exp_ptr = reinterpret_cast <int *> (&val);
-   int            x = *exp_ptr;
-   const int      log_2 = ((x >> 23) & 255) - 128;
-   x &= ~(255 << 23);
-   x += 127 << 23;
-   *exp_ptr = x;
+    union {
+        float f;
+        int i;
+    } v;
+    v.f = val;
+    const int log_2 = ((v.i >> 23) & 255) - 128;
+    v.i &= ~(255 << 23);
+    v.i += 127 << 23;
 
-   val = ((-1.0f/3) * val + 2) * val - 2.0f/3;   // (1)
+    v.f = ((-1.0f/3) * v.f + 2) * v.f - 2.0f/3;   // (1)
 
-   return (val + log_2);
+    return (v.f + log_2);
 }
 
+
 /**
  * This function is about 3 times faster than the system log() function
  * and has an error of about 0.01%
@@ -65,5 +81,36 @@ inline float fast_log10 (const float &val)
 }
 
 
+/**
+ * This function is about twice as fast as the system pow(x,y) function
+ */
+inline float fast_pow(const float val1, const float val2)
+{
+   return _fast_pow2(val2 * _fast_log2(val1));
+}
+
+
+/*
+ * Haven't seen this elsewhere, probably because it is too obvious?
+ * Anyway, these functions are intended for 32-bit floating point numbers
+ * only and should work a bit faster than the regular ones.
+ */
+inline float fast_abs(float f)
+{
+    int i=((*(int*)&f)&0x7fffffff);
+    return (*(float*)&i);
+}
+
+inline float fast_neg(float f)
+{
+    int i=((*(int*)&f)^0x80000000);
+    return (*(float*)&i);
+}
+
+inline int fast_sgn(float f)
+{
+    return 1+(((*(int*)&f)>>31)<<1);
+}
+
 #endif // !_SG_FMATH_HXX