add zip and parity stuff

fileUtilities/parity.go

@@ -0,0 +1,55 @@
+package fileUtilities
+
+import (
+	"fmt"
+	"io"
+)
+
+func parityStream(in1, in2 io.Reader, out io.Writer) error {
+	var err error
+	byteSize := 1024
+	done1 := false
+	done2 := false
+	for !done1 && !done2 {
+		// get bytes from in1 and in2 and write the parity to buf
+		// if either in1 or in2 is done, write the remaining bytes from the other to buf
+		in1Bytes := make([]byte, byteSize)
+		in2Bytes := make([]byte, byteSize)
+		read1 := 0
+		read2 := 0
+		if !done1 {
+			read1, err = in1.Read(in1Bytes)
+			if err != nil {
+				if err == io.EOF {
+					done1 = true
+				} else {
+					return err
+				}
+			}
+		}
+		if !done2 {
+			read2, err = in2.Read(in2Bytes)
+			if err != nil {
+				if err == io.EOF {
+					done2 = true
+				} else {
+					return err
+				}
+			}
+		}
+		maxRead := read1
+		if read2 > maxRead {
+			maxRead = read2
+		}
+
+		parityBytes := make([]byte, maxRead)
+		for i := 0; i < maxRead; i++ {
+			parityBytes[i] = in1Bytes[i] ^ in2Bytes[i]
+		}
+		_, err := out.Write(parityBytes)
+		if err != nil {
+			return fmt.Errorf("error writing to buffer: %w", err)
+		}
+	}
+	return nil
+}