fusl/src/sched/sched_cpucount.c

#define _GNU_SOURCE
#include <sched.h>

int __sched_cpucount(size_t size, const cpu_set_t* set) {
  size_t i, j, cnt = 0;
  const unsigned char* p = (const void*)set;
  for (i = 0; i < size; i++)
    for (j = 0; j < 8; j++)
      if (p[i] & (1 << j))
        cnt++;
  return cnt;
}