added Galois LFSR PRNG

[blank.git] / src / noise.hpp

diff --git a/src/noise.hpp b/src/noise.hpp
index 4c26de92eadf0ae3bacd679cc069e0337bf27861..166a60a71058b998d60df732f752259b993beea4 100644 (file)
--- a/src/noise.hpp
+++ b/src/noise.hpp
@@ -1,11 +1,40 @@
 #ifndef BLANK_NOISE_HPP_
 #define BLANK_NOISE_HPP_
 
+#include <cstdint>
+#include <limits>
 #include <glm/glm.hpp>
 
 
 namespace blank {
 
+class GaloisLFSR {
+
+public:
+       // seed should be non-zero
+       explicit GaloisLFSR(std::uint64_t seed);
+
+       // get the next bit
+       bool operator ()();
+
+       template<class T>
+       void operator ()(T &out) {
+               constexpr int num_bits =
+                       std::numeric_limits<T>::digits +
+                       std::numeric_limits<T>::is_signed;
+               for (int i = 0; i < num_bits; ++i) {
+                       operator ()();
+               }
+               out = static_cast<T>(state);
+       }
+
+private:
+       std::uint64_t state;
+       // bits 64, 63, 61, and 60 set to 1 (counting from 1 lo to hi)
+       static constexpr std::uint64_t mask = 0xD800000000000000;
+
+};
+
 /// (3D only) adaptation of Stefan Gustavson's SimplexNoise java class
 class SimplexNoise {