copy langext & termext from ffsclient

langext/bytes.go

@@ -1,6 +1,9 @@
 package langext
 
-import "fmt"
+import (
+	"errors"
+	"fmt"
+)
 
 func FormatBytesToSI(b uint64) string {
 	const unit = 1000
@@ -14,3 +17,30 @@ func FormatBytesToSI(b uint64) string {
 	}
 	return fmt.Sprintf("%.1f %cB", float64(b)/float64(div), "kMGTPE"[exp])
 }
+
+func BytesXOR(a []byte, b []byte) ([]byte, error) {
+	if len(a) != len(b) {
+		return nil, errors.New("length mismatch")
+	}
+
+	r := make([]byte, len(a))
+
+	for i := 0; i < len(a); i++ {
+		r[i] = a[i] ^ b[i]
+	}
+
+	return r, nil
+}
+
+func FormatBytes(b int64) string {
+	const unit = 1024
+	if b < unit {
+		return fmt.Sprintf("%d B", b)
+	}
+	div, exp := int64(unit), 0
+	for n := b / unit; n >= unit; n /= unit {
+		div *= unit
+		exp++
+	}
+	return fmt.Sprintf("%.1f %ciB", float64(b)/float64(div), "KMGTPE"[exp])
+}