test random ints of various widths

[blank.git] / src / rand / GaloisLFSR.hpp

diff --git a/src/rand/GaloisLFSR.hpp b/src/rand/GaloisLFSR.hpp
index 88a1d37e899f1b26e369a727a804d7755ba7d33e..81652d85f54a64cd628c22a95d3493b6de6476cd 100644 (file)
--- a/src/rand/GaloisLFSR.hpp
+++ b/src/rand/GaloisLFSR.hpp
@@ -11,10 +11,25 @@ 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 +42,41 @@ 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) {
+               return c[Next<typename Container::size_type>() % c.size()];
+       }
+       template<class Container>
+       typename Container::const_reference From(const Container &c) {
+               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