src/sched/linux/sched_getcpuisset.cpp

//===-- Implementation of sched_getcpuisset -------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//

#include "src/sched/sched_getcpuisset.h"

#include "src/__support/common.h"            // LLVM_LIBC_FUNCTION
#include "src/__support/macros/config.h"     // LIBC_NAMESPACE_DECL
#include "src/__support/macros/null_check.h" // LIBC_CRASH_ON_NULLPTR

#include "hdr/sched_macros.h" // NCPUBITS
#include "hdr/types/cpu_set_t.h"
#include "hdr/types/size_t.h"

namespace LIBC_NAMESPACE_DECL {

LLVM_LIBC_FUNCTION(int, __sched_getcpuisset,
                   (int cpu, const size_t cpuset_size, cpu_set_t *set)) {
  LIBC_CRASH_ON_NULLPTR(set);

  if (static_cast<size_t>(cpu) / 8 < cpuset_size) {
    const size_t element_index = static_cast<size_t>(cpu) / NCPUBITS;
    const size_t bit_position = static_cast<size_t>(cpu) % NCPUBITS;

    const unsigned long mask = 1UL << bit_position;
    return (set->__mask[element_index] & mask) != 0;
  }

  return 0;
}

} // namespace LIBC_NAMESPACE_DECL