xref: /freebsd/contrib/llvm-project/libcxx/src/pstl/libdispatch.cpp (revision 5036d9652a5701d00e9e40ea942c278e9f77d33d)
1 //===----------------------------------------------------------------------===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 
9 #include <__algorithm/min.h>
10 #include <__config>
11 #include <__pstl/backends/libdispatch.h>
12 #include <dispatch/dispatch.h>
13 
14 _LIBCPP_BEGIN_NAMESPACE_STD
15 namespace __pstl::__libdispatch {
16 
17 void __dispatch_apply(size_t chunk_count, void* context, void (*func)(void* context, size_t chunk)) noexcept {
18   ::dispatch_apply_f(chunk_count, DISPATCH_APPLY_AUTO, context, func);
19 }
20 
21 __chunk_partitions __partition_chunks(ptrdiff_t element_count) noexcept {
22   __chunk_partitions partitions;
23   partitions.__chunk_count_      = std::max<ptrdiff_t>(1, element_count / 256);
24   partitions.__chunk_size_       = element_count / partitions.__chunk_count_;
25   partitions.__first_chunk_size_ = element_count - (partitions.__chunk_count_ - 1) * partitions.__chunk_size_;
26   if (partitions.__chunk_count_ == 0 && element_count > 0)
27     partitions.__chunk_count_ = 1;
28   return partitions;
29 }
30 
31 } // namespace __pstl::__libdispatch
32 _LIBCPP_END_NAMESPACE_STD
33