musl-tcc/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;
}