#include <assert.h>

static const unsigned char data[] = {0xde, 0xca, 0xfa, 0xde};
static unsigned char buffer[4];

void *memset(void *s, int c, long unsigned n);
void *memcpy(void *restrict dest, const void *restrict src, long unsigned n);

int
main(void)
{
  memset(buffer, 0xae, sizeof(data));
  for (unsigned i = 0; i < sizeof(data); ++i) assert(buffer[i] == 0xae);

  memcpy(buffer, data, sizeof(data));
  for (unsigned i = 0; i < sizeof(data); ++i) assert(buffer[i] == data[i]);
}