rand/system: add system generator for Linux

CMakeLists.txt

@@ -102,6 +102,8 @@ if (LINUX)
     list (APPEND UTIL_FILES
         thread/event_futex.cpp
         thread/flag_futex.cpp
+        rand/system_linux.cpp
+        rand/system_linux.hpp
         )
 endif ()
 
@@ -144,6 +146,8 @@ if (WIN32)
         thread/event_win32.cpp
         library_win32.cpp
         library_win32.hpp
+        rand/system_win32.cpp
+        rand/system_win32.hpp
         time_win32.cpp
         win32/windows.hpp
         win32/except.cpp
@@ -436,6 +440,7 @@ list (
     rand/mwc64x.hpp
     rand/pcg.cpp
     rand/pcg.hpp
+    rand/system.hpp
     random.cpp
     random.hpp
     range.cpp

rand/system.hpp

@@ -0,0 +1,19 @@
+/*
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ *
+ * Copyright 2019 Danny Robson <danny@nerdcruft.net>
+ */
+
+#pragma once
+
+#include "../platform.hpp"
+
+#if defined(PLATFORM_WIN32)
+    #include "system_win32.hpp"
+#elif defined(PLATFORM_LINUX)
+    #include "system_linux.hpp"
+#else
+    #error "Unhandled platform"
+#endif

rand/system_linux.cpp

@@ -0,0 +1,62 @@
+/*
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ *
+ * Copyright 2019 Danny Robson <danny@nerdcruft.net>
+ */
+
+#include "system_linux.hpp"
+
+#include "../posix/except.hpp"
+#include "../io.hpp"
+
+#include <sys/ioctl.h>
+#include <linux/random.h>
+
+
+using cruft::rand::linux::device;
+
+
+///////////////////////////////////////////////////////////////////////////////
+static std::string const& default_source (void)
+{
+    static std::string const s_path = "/dev/urandom";
+    return s_path;
+}
+
+
+//-----------------------------------------------------------------------------
+device::device ():
+    device (default_source ())
+{ ; }
+
+
+//-----------------------------------------------------------------------------
+device::device (std::string const &token)
+    : m_fd (token, O_RDONLY | O_BINARY)
+{ ; }
+
+
+///////////////////////////////////////////////////////////////////////////////
+device::result_type
+device::operator() (void)
+{
+    result_type res;
+    cruft::read (m_fd, cruft::make_byte_view<u08> (res));
+    return res;
+}
+
+
+///////////////////////////////////////////////////////////////////////////////
+double
+device::entropy () const noexcept
+{
+    int val;
+
+    cruft::posix::error::try_code (
+        ioctl (m_fd.native (), RNDGETENTCNT, &val)
+    );
+
+    return val < 0 ? 0. : double (val);
+}

rand/system_linux.hpp

@@ -0,0 +1,40 @@
+/*
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ *
+ * Copyright 2019 Danny Robson <danny@nerdcruft.net>
+ */
+
+#pragma once
+
+#include "../posix/fd.hpp"
+
+
+namespace cruft::rand {
+    namespace linux {
+        /// Models std::random_device and is suitable as a drop-in replacement.
+        class device {
+        public:
+            using result_type = unsigned;
+
+            device ();
+            device (std::string const&);
+            device (device const &) = delete;
+
+            device& operator= (device const&) = delete;
+
+            result_type operator() (void);
+
+            double entropy (void) const noexcept;
+
+            static constexpr result_type min (void) { return std::numeric_limits<result_type>::min (); }
+            static constexpr result_type max (void) { return std::numeric_limits<result_type>::max (); }
+
+        private:
+            cruft::posix::fd m_fd;
+        };
+    }
+
+    using system = linux::device;
+}

rand/system_win32.hpp

@@ -0,0 +1,8 @@
+/*
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ *
+ * Copyright 2019 Danny Robson <danny@nerdcruft.net>
+ */
+

test/rand/buckets.cpp

@@ -2,37 +2,24 @@
 #include "rand/lcg.hpp"
 #include "rand/mwc64x.hpp"
 #include "rand/pcg.hpp"
+#include "rand/rdrand.hpp"
+#include "rand/system.hpp"
 
 #include "tap.hpp"
 #include "maths.hpp"
 #include "types/string.hpp"
+#include "introspection.hpp"
 
 
-///////////////////////////////////////////////////////////////////////////////
-template <>
-std::string
-type_to_string<cruft::rand::xorshift<uint32_t>> (void) { return "xorshift<uint32_t>"; }
-
-template <>
-std::string
-type_to_string<cruft::rand::xorshift<uint64_t>> (void) { return "xorshift<uint64_t>"; }
-
-template <> std::string type_to_string<cruft::rand::lcg_t> (void) { return "lcg_t"; }
-
-template <> std::string type_to_string<cruft::rand::mwc64x> (void) { return "mwc64x"; }
-
-template <> std::string type_to_string<cruft::rand::pcg_xsh_rr<u64,u32>> (void) { return "pcg_xsh_rr<64,32>"; }
-
-
-///////////////////////////////////////////////////////////////////////////////
-/// check random outputs are roughly divisible between a number of fixed width
-/// buckets.
+/// //////////////////////////////////////////////////////////////////////////////
+/// Check that outputs from a UniformRandomBitGenerator are roughly divisible
+/// between a number of fixed width buckets.
 ///
-/// this is not anything close to a strict statistical test. it is more aimed
+/// This is not anything close to a strict statistical test. It is more aimed
 /// at link testing and basic functionality verification within a small
 /// resource footprint (ie, fast unit testing).
-template <typename G, typename ...Args>
-void
+template <typename GeneratorT, typename ...Args>
+static void
 test_buckets (cruft::TAP::logger &tap, Args&& ...args)
 {
     constexpr unsigned BUCKET_BITS  = 8u;
@@ -40,7 +27,7 @@ test_buckets (cruft::TAP::logger &tap, Args&& ...args)
     constexpr unsigned EXPECTED     = 1024u;
     constexpr unsigned ITERATIONS = BUCKET_COUNT * EXPECTED;
 
-    G gen (std::forward<Args> (args)...);
+    GeneratorT gen (std::forward<Args> (args)...);
     std::uniform_int_distribution<int> dist (0, BUCKET_COUNT - 1);
 
     unsigned buckets[BUCKET_COUNT] = {};
@@ -51,7 +38,8 @@ test_buckets (cruft::TAP::logger &tap, Args&& ...args)
         std::find_if (std::cbegin (buckets),
                       std::cend   (buckets),
                       [] (auto v) { return v < EXPECTED * 7 / 8; }) == std::cend (buckets),
-        "bucket counts for %s", type_to_string<G> ());
+        "bucket counts for %s", cruft::type_name<GeneratorT> ()
+    );
 }
 
 
@@ -66,6 +54,7 @@ main (int,char**)
     test_buckets<cruft::rand::lcg_t> (tap, 0x1234u);
     test_buckets<cruft::rand::mwc64x> (tap, 0x1234u);
     test_buckets<cruft::rand::pcg_xsh_rr<>> (tap, 0x1234u);
+    test_buckets<cruft::rand::system> (tap);
 
     return tap.status ();
 }