include/boost/capy/buffers/buffer_copy.hpp

100.0% Lines (36/36) 100.0% Functions (10/11)

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1		//
2		// Copyright (c) 2023 Vinnie Falco (vinnie.falco@gmail.com)
3		//
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)
6		//
7		// Official repository: https://github.com/cppalliance/capy
8		//
9
10		#ifndef BOOST_CAPY_BUFFERS_BUFFER_COPY_HPP
11		#define BOOST_CAPY_BUFFERS_BUFFER_COPY_HPP
12
13		#include <boost/capy/detail/config.hpp>
14		#include <boost/capy/buffers.hpp>
15		#include <cstring>
16		#include <utility>
17
18		namespace boost {
19		namespace capy {
20
21		/** Copy the contents of a buffer sequence into another buffer sequence.
22
23		This function copies bytes from the constant buffer sequence `src` into
24		the mutable buffer sequence `dest`, stopping when any limit is reached.
25
26		@par Constraints
27		@code
28		MutableBufferSequence<decltype(dest)> &&
29		ConstBufferSequence<decltype(src)>
30		@endcode
31
32		@return The number of bytes copied, equal to
33		`std::min(size(dest), size(src), at_most)`.
34
35		@param dest The destination buffer sequence.
36		@param src The source buffer sequence.
37		@param at_most The maximum bytes to copy. Default copies all available.
38		*/
39		constexpr struct buffer_copy_mrdocs_workaround_t
40		{
41		template<
42		MutableBufferSequence MB,
43		ConstBufferSequence CB>
44		std::size_t
45	15198	operator()(
46		MB const& dest,
47		CB const& src,
48		std::size_t at_most = std::size_t(-1)) const noexcept
49		{
50	15198	std::size_t total = 0;
51	15198	std::size_t pos0 = 0;
52	15198	std::size_t pos1 = 0;
53	15198	auto const end0 = end(src);
54	15198	auto const end1 = end(dest);
55	15198	auto it0 = begin(src);
56	15198	auto it1 = begin(dest);
57	15198	while(
58	46531	total < at_most &&
59	66892	it0 != end0 &&
60	9334	it1 != end1)
61		{
62	25401	const_buffer b0 = *it0;
63	25401	mutable_buffer b1 = *it1;
64	25401	b0 += pos0;
65	25401	b1 += pos1;
66		std::size_t const amount =
67	76203	[&]
68		{
69	25401	std::size_t n = b0.size();
70	25401	if( n > b1.size())
71	5732	n = b1.size();
72	25401	if( n > at_most - total)
73	4902	n = at_most - total;
74	25401	if(n != 0)
75	23043	std::memcpy(
76		b1.data(),
77		b0.data(),
78		n);
79	25401	return n;
80	25401	}();
81	25401	total += amount;
82	25401	if(amount == b1.size())
83		{
84	7278	++it1;
85	7278	pos1 = 0;
86		}
87		else
88		{
89	18123	pos1 += amount;
90		}
91	25401	if(amount == b0.size())
92		{
93	16183	++it0;
94	16183	pos0 = 0;
95		}
96		else
97		{
98	9218	pos0 += amount;
99		}
100		}
101	15198	return total;
102		}
103		} buffer_copy {};
104
105		} // capy
106		} // boost
107
108		#endif
109