>go test binary1.go binary1_test.go -bench=.
testing: warning: no tests to run
PASS
BenchmarkWrite_int8        10000            171109 ns/op
BenchmarkWrite_uint8        5000            367821 ns/op
BenchmarkWrite_int8_p      10000            114706 ns/op
BenchmarkWrite_uint8_p     10000            115306 ns/op

// intDataSize returns the size of the data required to represent the data when encoded.
// It returns zero if the type cannot be implemented by the fast path in Read or Write.
func intDataSize(data interface{}) int {
    switch data := data.(type) {
    case int8, *int8, *uint8:
        return 1
    case []int8:
        return len(data)
    case []uint8:
        return len(data)