. /include/boost/capy /buffers /buffer_copy.hpp
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1   // 1   //
2   // Copyright (c) 2023 Vinnie Falco (vinnie.falco@gmail.com) 2   // Copyright (c) 2023 Vinnie Falco (vinnie.falco@gmail.com)
3   // 3   //
4   // Distributed under the Boost Software License, Version 1.0. (See accompanying 4   // Distributed under the Boost Software License, Version 1.0. (See accompanying
5   // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt) 5   // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
6   // 6   //
7   // Official repository: https://github.com/cppalliance/capy 7   // Official repository: https://github.com/cppalliance/capy
8   // 8   //
9   9  
10   #ifndef BOOST_CAPY_BUFFERS_BUFFER_COPY_HPP 10   #ifndef BOOST_CAPY_BUFFERS_BUFFER_COPY_HPP
11   #define BOOST_CAPY_BUFFERS_BUFFER_COPY_HPP 11   #define BOOST_CAPY_BUFFERS_BUFFER_COPY_HPP
12   12  
13   #include <boost/capy/detail/config.hpp> 13   #include <boost/capy/detail/config.hpp>
14   #include <boost/capy/buffers.hpp> 14   #include <boost/capy/buffers.hpp>
15   #include <cstring> 15   #include <cstring>
16   #include <utility> 16   #include <utility>
17   17  
18   namespace boost { 18   namespace boost {
19   namespace capy { 19   namespace capy {
20   20  
21   /** Copy the contents of a buffer sequence into another buffer sequence. 21   /** Copy the contents of a buffer sequence into another buffer sequence.
22   22  
23   This function copies bytes from the constant buffer sequence `src` into 23   This function copies bytes from the constant buffer sequence `src` into
24   the mutable buffer sequence `dest`, stopping when any limit is reached. 24   the mutable buffer sequence `dest`, stopping when any limit is reached.
25   25  
26   @par Constraints 26   @par Constraints
27   @code 27   @code
28   MutableBufferSequence<decltype(dest)> && 28   MutableBufferSequence<decltype(dest)> &&
29   ConstBufferSequence<decltype(src)> 29   ConstBufferSequence<decltype(src)>
30   @endcode 30   @endcode
31   31  
32   @return The number of bytes copied, equal to 32   @return The number of bytes copied, equal to
33   `std::min(size(dest), size(src), at_most)`. 33   `std::min(size(dest), size(src), at_most)`.
34   34  
35   @param dest The destination buffer sequence. 35   @param dest The destination buffer sequence.
36   @param src The source buffer sequence. 36   @param src The source buffer sequence.
37   @param at_most The maximum bytes to copy. Default copies all available. 37   @param at_most The maximum bytes to copy. Default copies all available.
38   */ 38   */
39   constexpr struct buffer_copy_mrdocs_workaround_t 39   constexpr struct buffer_copy_mrdocs_workaround_t
40   { 40   {
41   template< 41   template<
42   MutableBufferSequence MB, 42   MutableBufferSequence MB,
43   ConstBufferSequence CB> 43   ConstBufferSequence CB>
44   std::size_t 44   std::size_t
HITCBC 45   15252 operator()( 45   15252 operator()(
46   MB const& dest, 46   MB const& dest,
47   CB const& src, 47   CB const& src,
48   std::size_t at_most = std::size_t(-1)) const noexcept 48   std::size_t at_most = std::size_t(-1)) const noexcept
49   { 49   {
HITCBC 50   15252 std::size_t total = 0; 50   15252 std::size_t total = 0;
HITCBC 51   15252 std::size_t pos0 = 0; 51   15252 std::size_t pos0 = 0;
HITCBC 52   15252 std::size_t pos1 = 0; 52   15252 std::size_t pos1 = 0;
HITCBC 53   15252 auto const end0 = end(src); 53   15252 auto const end0 = end(src);
HITCBC 54   15252 auto const end1 = end(dest); 54   15252 auto const end1 = end(dest);
HITCBC 55   15252 auto it0 = begin(src); 55   15252 auto it0 = begin(src);
HITCBC 56   15252 auto it1 = begin(dest); 56   15252 auto it1 = begin(dest);
HITCBC 57   15252 while( 57   15252 while(
HITCBC 58   46654 total < at_most && 58   46654 total < at_most &&
HITCBC 59   67102 it0 != end0 && 59   67102 it0 != end0 &&
HITCBC 60   9398 it1 != end1) 60   9398 it1 != end1)
61   { 61   {
HITCBC 62   25459 const_buffer b0 = *it0; 62   25459 const_buffer b0 = *it0;
HITCBC 63   25459 mutable_buffer b1 = *it1; 63   25459 mutable_buffer b1 = *it1;
HITCBC 64   25459 b0 += pos0; 64   25459 b0 += pos0;
HITCBC 65   25459 b1 += pos1; 65   25459 b1 += pos1;
66   std::size_t const amount = 66   std::size_t const amount =
HITCBC 67   76377 [&] 67   76377 [&]
68   { 68   {
HITCBC 69   25459 std::size_t n = b0.size(); 69   25459 std::size_t n = b0.size();
HITCBC 70   25459 if( n > b1.size()) 70   25459 if( n > b1.size())
HITCBC 71   5748 n = b1.size(); 71   5748 n = b1.size();
HITCBC 72   25459 if( n > at_most - total) 72   25459 if( n > at_most - total)
HITCBC 73   4902 n = at_most - total; 73   4902 n = at_most - total;
HITCBC 74   25459 if(n != 0) 74   25459 if(n != 0)
HITCBC 75   23101 std::memcpy( 75   23101 std::memcpy(
76   b1.data(), 76   b1.data(),
77   b0.data(), 77   b0.data(),
78   n); 78   n);
HITCBC 79   25459 return n; 79   25459 return n;
HITCBC 80   25459 }(); 80   25459 }();
HITCBC 81   25459 total += amount; 81   25459 total += amount;
HITCBC 82   25459 if(amount == b1.size()) 82   25459 if(amount == b1.size())
83   { 83   {
HITCBC 84   7295 ++it1; 84   7295 ++it1;
HITCBC 85   7295 pos1 = 0; 85   7295 pos1 = 0;
86   } 86   }
87   else 87   else
88   { 88   {
HITCBC 89   18164 pos1 += amount; 89   18164 pos1 += amount;
90   } 90   }
HITCBC 91   25459 if(amount == b0.size()) 91   25459 if(amount == b0.size())
92   { 92   {
HITCBC 93   16225 ++it0; 93   16225 ++it0;
HITCBC 94   16225 pos0 = 0; 94   16225 pos0 = 0;
95   } 95   }
96   else 96   else
97   { 97   {
HITCBC 98   9234 pos0 += amount; 98   9234 pos0 += amount;
99   } 99   }
100   } 100   }
HITCBC 101   15252 return total; 101   15252 return total;
102   } 102   }
103   } buffer_copy {}; 103   } buffer_copy {};
104   104  
105   } // capy 105   } // capy
106   } // boost 106   } // boost
107   107  
108   #endif 108   #endif