refactor lut/motivity

1 files changed, 35 insertions, 0 deletions

diff --git a/common/utility.hpp b/common/utility.hpp
index ae14b48..de90d44 100644
--- a/common/utility.hpp
+++ b/common/utility.hpp
@@ -34,6 +34,33 @@ namespace rawaccel {
         return minsd(maxsd(v, lo), hi);
     }
 
+    template <typename T>
+    constexpr const T& min(const T& a, const T& b)
+    {
+        return (b < a) ? b : a;
+    }
+
+    template <typename T>
+    constexpr const T& max(const T& a, const T& b)
+    {
+        return (b < a) ? a : b;
+    }
+
+    template <typename T>
+    constexpr const T& clamp(const T& v, const T& lo, const T& hi)
+    {
+        return (v < lo) ? lo : (hi < v) ? hi : v;
+    }
+
+    constexpr double lerp(double a, double b, double t)
+    {
+        double x = a + t * (b - a);
+        if ((t > 1) == (a < b)) {
+            return maxsd(x, b);
+        }
+        return minsd(x, b);
+    }
+
     // returns the unbiased exponent of x if x is normal 
     inline int ilogb(double x)
     {
@@ -41,6 +68,14 @@ namespace rawaccel {
 	    return static_cast<int>((u.i >> 52) & 0x7ff) - 0x3ff;
     }
 
+    // returns x * 2^n if n is in [-1022, 1023] 
+    inline double scalbn(double x, int n)
+    {
+        union { double f; unsigned long long i; } u;
+        u.i = static_cast<unsigned long long>(0x3ff + n) << 52;
+        return x * u.f;
+    }
+
     inline bool infnan(double x)
     {
 	    return ilogb(x) == 0x400;