Drop (Un)MarshalBinary() methods

In hindsight they're not really needed. Tweak the examples accordingly.

Also improve the README.

README.md

@@ -5,3 +5,7 @@
 
 windows
 =======
+
+A collection of types native to Windows but are useful on non-Windows platforms.
+
+The `FILETIME`-comparable type is the sole export which is a 1:1 copy of the one from `golang.org/x/sys/windows`. However, that package isn't available for all platforms and this particular type gets used in other protocols and file types such as NTLMv2 and 7-Zip.

filetime.go

@@ -2,11 +2,6 @@
 // are useful on non-Windows platforms.
 package windows
 
-import (
-	"bytes"
-	"encoding/binary"
-)
-
 // Taken from golang.org/x/sys/windows
 
 const offset int64 = 116444736000000000
@@ -15,23 +10,13 @@ const offset int64 = 116444736000000000
 // as the number of 100-nanosecond intervals that have elapsed since
 // 00:00:00 UTC, January 1, 1601. This code is taken from the
 // golang.org/x/sys/windows package where it's not available for non-Windows
-// platforms however various file formats and protocols pass variations of
-// this type about so it's useful to have it available for interoperability
-// purposes. It implements the encoding.BinaryMarshaler and
-// encoding.BinaryUnmarshaler interfaces.
+// platforms however various file formats and protocols pass this structure
+// about so it's useful to have it available for interoperability purposes.
 type Filetime struct {
 	LowDateTime  uint32
 	HighDateTime uint32
 }
 
-// MarshalBinary encodes Filetime ft into a binary form and returns the
-// result.
-func (ft *Filetime) MarshalBinary() ([]byte, error) {
-	w := new(bytes.Buffer)
-	_ = binary.Write(w, binary.LittleEndian, ft)
-	return w.Bytes(), nil
-}
-
 // Nanoseconds returns Filetime ft in nanoseconds
 // since Epoch (00:00:00 UTC, January 1, 1970).
 func (ft *Filetime) Nanoseconds() int64 {
@@ -44,12 +29,6 @@ func (ft *Filetime) Nanoseconds() int64 {
 	return nsec
 }
 
-// UnmarshalBinary decodes Filetime ft from binary form.
-func (ft *Filetime) UnmarshalBinary(b []byte) error {
-	r := bytes.NewBuffer(b)
-	return binary.Read(r, binary.LittleEndian, ft)
-}
-
 // NsecToFiletime converts nanoseconds to the equivalent Filetime type.
 func NsecToFiletime(nsec int64) (ft Filetime) {
 	// convert into 100-nanosecond

filetime_test.go

@@ -1,29 +1,23 @@
 package windows
 
 import (
-	"encoding/hex"
 	"fmt"
+	"time"
 )
 
-func ExampleFiletime_MarshalBinary() {
-	ft := NsecToFiletime(1595265310000000000) // time.Date(2020, 7, 20, 17, 15, 10, 0, time.UTC).UnixNano()
+func ExampleNsecToFiletime() {
+	ft := NsecToFiletime(time.Date(2020, 7, 20, 17, 15, 10, 0, time.UTC).UnixNano())
 
-	b, err := ft.MarshalBinary()
-	if err != nil {
-		panic(err)
-	}
-
-	fmt.Print(hex.Dump(b))
-	// Output: 00000000  00 a3 7e 52 b9 5e d6 01                           |..~R.^..|
+	fmt.Println(ft)
+	// Output: {1384030976 30826169}
 }
 
-func ExampleFiletime_UnmarshalBinary() {
-	ft := new(Filetime)
-
-	if err := ft.UnmarshalBinary([]byte{0x00, 0xa3, 0x7e, 0x52, 0xb9, 0x5e, 0xd6, 0x01}); err != nil {
-		panic(err)
+func ExampleFiletime_Nanoseconds() {
+	ft := Filetime{
+		1384030976,
+		30826169,
 	}
 
-	fmt.Println(ft.Nanoseconds())
-	// Output: 1595265310000000000
+	fmt.Println(time.Unix(0, ft.Nanoseconds()).UTC())
+	// Output: 2020-07-20 17:15:10 +0000 UTC
 }