1 // Copyright 2019 Peter Dimov
2 //
3 // Distributed under the Boost Software License, Version 1.0.
4 // http://www.boost.org/LICENSE_1_0.txt
5
6 #include <boost/endian/detail/order.hpp>
7 #include <boost/core/lightweight_test.hpp>
8 #include <boost/config.hpp>
9 #include <boost/cstdint.hpp>
10 #include <cstddef>
11 #include <ostream>
12 #include <iomanip>
13
14 #if defined(_MSC_VER)
15 # pragma warning(disable: 4127) // conditional expression is constant
16 #endif
17
18 class byte_span
19 {
20 private:
21
22 unsigned char const * p_;
23 std::size_t n_;
24
25 public:
26
byte_span(unsigned char const * p,std::size_t n)27 byte_span( unsigned char const * p, std::size_t n ): p_( p ), n_( n )
28 {
29 }
30
byte_span(unsigned char const (& a)[N])31 template<std::size_t N> explicit byte_span( unsigned char const (&a)[ N ] ): p_( a ), n_( N )
32 {
33 }
34
operator ==(byte_span const & r) const35 bool operator==( byte_span const& r ) const
36 {
37 if( n_ != r.n_ ) return false;
38
39 for( std::size_t i = 0; i < n_; ++i )
40 {
41 if( p_[ i ] != r.p_[ i ] ) return false;
42 }
43
44 return true;
45 }
46
operator <<(std::ostream & os,byte_span s)47 friend std::ostream& operator<<( std::ostream& os, byte_span s )
48 {
49 if( s.n_ == 0 ) return os;
50
51 os << std::hex << std::setfill( '0' ) << std::uppercase;
52
53 os << std::setw( 2 ) << +s.p_[ 0 ];
54
55 for( std::size_t i = 1; i < s.n_; ++i )
56 {
57 os << ':' << std::setw( 2 ) << +s.p_[ i ];
58 }
59
60 os << std::dec << std::setfill( ' ' ) << std::nouppercase;
61
62 return os;
63 }
64 };
65
main()66 int main()
67 {
68 boost::uint64_t v = static_cast<boost::uint64_t>( 0x0102030405060708ull );
69 byte_span v2( reinterpret_cast<unsigned char const*>( &v ), sizeof(v) );
70
71 if( boost::endian::order::native == boost::endian::order::little )
72 {
73 unsigned char w[] = { 8, 7, 6, 5, 4, 3, 2, 1 };
74 BOOST_TEST_EQ( v2, byte_span( w ) );
75 }
76 else if( boost::endian::order::native == boost::endian::order::big )
77 {
78 unsigned char w[] = { 1, 2, 3, 4, 5, 6, 7, 8 };
79 BOOST_TEST_EQ( v2, byte_span( w ) );
80 }
81 else
82 {
83 BOOST_ERROR( "boost::endian::order::native is neither big nor little" );
84 }
85
86 return boost::report_errors();
87 }
88