Add bit_floor_test

test/Jamfile.v2

@@ -228,6 +228,7 @@ run bit_countr_test.cpp ;
 run bit_countl_test.cpp ;
 run bit_width_test.cpp ;
 run has_single_bit_test.cpp ;
+run bit_floor_test.cpp ;
 
 use-project /boost/core/swap : ./swap ;
 build-project ./swap ;

test/bit_floor_test.cpp

@@ -0,0 +1,53 @@
+// Test for boost/core/bit.hpp (bit_floor)
+//
+// Copyright 2020 Peter Dimov
+// Distributed under the Boost Software License, Version 1.0.
+// https://www.boost.org/LICENSE_1_0.txt
+
+#include <boost/core/bit.hpp>
+#include <boost/core/lightweight_test.hpp>
+#include <boost/core/detail/splitmix64.hpp>
+#include <boost/cstdint.hpp>
+#include <limits>
+
+template<class T> void test_bit_floor( T x )
+{
+    T y = boost::core::bit_floor( x );
+
+    if( x == 0 )
+    {
+        BOOST_TEST_EQ( y, 0 );
+    }
+    else
+    {
+        BOOST_TEST( boost::core::has_single_bit( y ) );
+        BOOST_TEST_LE( y, x );
+        BOOST_TEST_GT( y, x >> 1 );
+    }
+}
+
+int main()
+{
+    {
+        test_bit_floor( static_cast<unsigned char>( 0 ) );
+        test_bit_floor( static_cast<unsigned short>( 0 ) );
+        test_bit_floor( static_cast<unsigned int>( 0 ) );
+        test_bit_floor( static_cast<unsigned long>( 0 ) );
+        test_bit_floor( static_cast<unsigned long long>( 0 ) );
+    }
+
+    boost::detail::splitmix64 rng;
+
+    for( int i = 0; i < 1/*000*/; ++i )
+    {
+        boost::uint64_t x = rng();
+
+        test_bit_floor( static_cast<unsigned char>( x ) );
+        test_bit_floor( static_cast<unsigned short>( x ) );
+        test_bit_floor( static_cast<unsigned int>( x ) );
+        test_bit_floor( static_cast<unsigned long>( x ) );
+        test_bit_floor( static_cast<unsigned long long>( x ) );
+    }
+
+    return boost::report_errors();
+}