X-Git-Url: http://git.localhorst.tv/?a=blobdiff_plain;f=src%2Frand%2FGaloisLFSR.hpp;h=f8a61e23f3f7c721689d7e0ff4a2404aa671f412;hb=fab49d91255ef7d265817213c3da7e5f81df97a0;hp=88a1d37e899f1b26e369a727a804d7755ba7d33e;hpb=b7d09e1e35ef90282c97509e0020b20db3c7ea9f;p=blank.git

diff --git a/src/rand/GaloisLFSR.hpp b/src/rand/GaloisLFSR.hpp
index 88a1d37..f8a61e2 100644
--- a/src/rand/GaloisLFSR.hpp
+++ b/src/rand/GaloisLFSR.hpp
@@ -1,6 +1,7 @@
 #ifndef BLANK_RAND_GALOISLFSR_HPP_
 #define BLANK_RAND_GALOISLFSR_HPP_
 
+#include <cassert>
 #include <cstdint>
 #include <limits>
 
@@ -11,10 +12,25 @@ class GaloisLFSR {
 
 public:
 	// seed should be non-zero
-	explicit GaloisLFSR(std::uint64_t seed) noexcept;
+	explicit GaloisLFSR(std::uint64_t seed) noexcept
+	: state(seed) {
+		if (state == 0) {
+			state = 1;
+		}
+	}
 
 	// get the next bit
-	bool operator ()() noexcept;
+	bool operator ()() noexcept {
+		bool result = state & 1;
+		state >>= 1;
+		if (result) {
+			state |= 0x8000000000000000;
+			state ^= mask;
+		} else {
+			state &= 0x7FFFFFFFFFFFFFFF;
+		}
+		return result;
+	}
 
 	template<class T>
 	T operator ()(T &out) noexcept {
@@ -27,12 +43,43 @@ public:
 		return out = static_cast<T>(state);
 	}
 
+	/// special case for randrom(boolean), since static_cast<bool>(0b10) == true
+	bool operator ()(bool &out) noexcept {
+		return out = operator ()();
+	}
+
+	template<class T>
+	T Next() noexcept {
+		T next;
+		return (*this)(next);
+	}
+
+	float SNorm() noexcept {
+		return float(Next<std::uint32_t>()) * (1.0f / 2147483647.5f) - 1.0f;
+	}
+
+	float UNorm() noexcept {
+		return float(Next<std::uint32_t>()) * (1.0f / 4294967295.0f);
+	}
+
+	template<class Container>
+	typename Container::reference From(Container &c) {
+		assert(c.size() > 0);
+		return c[Next<typename Container::size_type>() % c.size()];
+	}
+	template<class Container>
+	typename Container::const_reference From(const Container &c) {
+		assert(c.size() > 0);
+		return c[Next<typename Container::size_type>() % c.size()];
+	}
+
 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;
 
 };
+
 }
 
 #endif