buf[n-7] = 'x'
		for i := 0; i < b.N; i++ {
			j := Count(buf, buf[n-7:])
			if j != 1 {
				b.Fatal("bad count", j)
			}
		}
		buf[n-1] = '\x00'
		buf[n-7] = '\x00'
	})
}

func BenchmarkCountSingle(b *testing.B) {
	benchBytes(b, indexSizes, func(b *testing.B, n int) {
		buf := bmbuf[0:n]
		step := 8
		for i := 0; i < len(buf); i += step {
			buf[i] = 1
		}
		expect := (len(buf) + (step - 1)) / step