Generate mask on the fly

encoding/gsm7.go

@@ -7,17 +7,6 @@ import (
 
 type GSM7Coder struct{}
 
-var masks = []byte{
-	0b00000000,
-	0b00000001,
-	0b00000011,
-	0b00000111,
-	0b00001111,
-	0b00011111,
-	0b00111111,
-	0b01111111,
-	0b11111111,
-}
 
 func (c *GSM7Coder) Encode(s string, buf *bytes.Buffer) error {
 	// utf8 := *(*[]byte)(unsafe.Pointer(&s))
@@ -33,14 +22,14 @@ func (c *GSM7Coder) Encode(s string, buf *bytes.Buffer) error {
 		if bindex == 0 {
 			continue
 		}
-		mask := masks[bitshift]
+		mask := byte(255 >> (8 - bitshift))
 		masked := (mask & septet) << (8 - bitshift)
 		utf8[bindex-offset] |= masked
 		utf8[bindex] >>= bitshift
 
 		buf.WriteByte(utf8[bindex-offset])
 		bitshift++
-		if utf8[bindex] == 0 {
+		if bitshift == 8 {
 			offset++
 			bitshift = 1
 		}