Refactor encoding to use *string instead of string as input

I don't want to clone the whole input string

encoding/gsm7_test.go

@@ -22,7 +22,7 @@ func TestGSM7EncodeSimpleASCIIString(t *testing.T) {
 	input := short8nString
 
 	expected := short8nStringEncodedBytes
-	err := coder.Encode(input, &buf)
+	err := coder.Encode(&input, &buf)
 
 	if err != nil {
 		t.Errorf("Expected no error, but got %v", err)
@@ -39,7 +39,7 @@ func TestGSM7EncodeComplexASCIIString(t *testing.T) {
 	input := longNot8nString
 
 	expected := longNot8nStringEncodedBytes
-	err := coder.Encode(input, &buf)
+	err := coder.Encode(&input, &buf)
 
 	if err != nil {
 		t.Errorf("Expected no error, but got %v", err)
@@ -56,7 +56,7 @@ func TestGSM7EncodeComplex8nASCIIString(t *testing.T) {
 	input := "Ducks are fucking great, they quacks, O quackers, what the fuck."
 
 	expected := long8nStringEncodedBytes
-	err := coder.Encode(input, &buf)
+	err := coder.Encode(&input, &buf)
 
 	if err != nil {
 		t.Errorf("Expected no error, but got %v", err)
@@ -74,7 +74,7 @@ func TestGSM7EncodeDoesNotAllocateMoreThanNecessary(t *testing.T) {
 	buf.Reset()
 
 	expected := buf.Cap()
-	err := coder.Encode(input, buf)
+	err := coder.Encode(&input, buf)
 	actual := buf.Cap()
 
 	if err != nil {
@@ -93,7 +93,7 @@ func TestGSM7EncodeDoesAllocateWhenNecessary(t *testing.T) {
 	buf.Reset()
 
 	original := buf.Cap()
-	err := coder.Encode(input, &buf)
+	err := coder.Encode(&input, &buf)
 	modified := buf.Cap()
 
 	if err != nil {
@@ -111,7 +111,7 @@ func TestGSM7EncodeEmptyString(t *testing.T) {
 	input := ""
 
 	expected := []byte{}
-	err := coder.Encode(input, &buf)
+	err := coder.Encode(&input, &buf)
 
 	if err != nil {
 		t.Errorf("Expected no error, but got %v", err)
@@ -330,7 +330,7 @@ func BenchmarkGSM7EncodeSimpleASCIIString(b *testing.B) {
 	b.ResetTimer()
 
 	for i := 0; i < b.N; i++ {
-		coder.Encode(input, &buf)
+		coder.Encode(&input, &buf)
 	}
 }
 
@@ -341,7 +341,7 @@ func BenchmarkGSM7EncodeComplexASCIIString(b *testing.B) {
 	b.ResetTimer()
 
 	for i := 0; i < b.N; i++ {
-		coder.Encode(input, &buf)
+		coder.Encode(&input, &buf)
 	}
 }
 
@@ -352,7 +352,7 @@ func BenchmarkGSM7EncodeComplex8nASCIIString(b *testing.B) {
 	b.ResetTimer()
 
 	for i := 0; i < b.N; i++ {
-		coder.Encode(input, &buf)
+		coder.Encode(&input, &buf)
 	}
 }
 
@@ -364,6 +364,6 @@ func BenchmarkGSM7EncodeComplex8nASCIIStringPrealloc(b *testing.B) {
 	for i := 0; i < b.N; i++ {
 		buf := bytes.NewBuffer(make([]byte, GSM7EncodesInto(&input)))
 		buf.Reset()
-		coder.Encode(input, buf)
+		coder.Encode(&input, buf)
 	}
 }