diff --git a/diff.go b/diff/diff.go
similarity index 79%
rename from diff.go
rename to diff/diff.go
index 5e1de99..1ed4cda 100644
--- a/diff.go
+++ b/diff/diff.go
@@ -1,10 +1,11 @@
-package bsdiff
+package diff
 
 import (
 	"io"
 	"io/ioutil"
 
 	"github.com/dsnet/compress/bzip2"
+	"github.com/icedream/go-bsdiff/internal"
 	"github.com/icedream/go-bsdiff/internal/native"
 )
 
@@ -18,7 +19,7 @@ func Diff(oldReader, newReader io.Reader, patchWriter io.Writer) (err error) {
 		return
 	}
 
-	if err = writeHeader(patchWriter, uint64(len(newBytes))); err != nil {
+	if err = internal.WriteHeader(patchWriter, uint64(len(newBytes))); err != nil {
 		return
 	}
 
diff --git a/magic.go b/internal/magic.go
similarity index 79%
rename from magic.go
rename to internal/magic.go
index b64530e..21766eb 100644
--- a/magic.go
+++ b/internal/magic.go
@@ -1,4 +1,4 @@
-package bsdiff
+package internal
 
 import (
 	"encoding/binary"
@@ -14,7 +14,7 @@ var (
 	magicText = []byte("ENDSLEY/BSDIFF43")
 )
 
-func writeHeader(w io.Writer, size uint64) (err error) {
+func WriteHeader(w io.Writer, size uint64) (err error) {
 	if _, err = w.Write(magicText); err != nil {
 		return
 	}
@@ -22,7 +22,7 @@ func writeHeader(w io.Writer, size uint64) (err error) {
 	return
 }
 
-func readHeader(r io.Reader) (size uint64, err error) {
+func ReadHeader(r io.Reader) (size uint64, err error) {
 	magicBuf := make([]byte, len(magicText))
 	n, err := r.Read(magicBuf)
 	if err != nil {
diff --git a/main.go b/main.go
new file mode 100644
index 0000000..2d0e7f3
--- /dev/null
+++ b/main.go
@@ -0,0 +1,16 @@
+package bsdiff
+
+import (
+	"io"
+
+	"github.com/icedream/go-bsdiff/diff"
+	"github.com/icedream/go-bsdiff/patch"
+)
+
+func Diff(oldReader, newReader io.Reader, patchWriter io.Writer) (err error) {
+	return diff.Diff(oldReader, newReader, patchWriter)
+}
+
+func Patch(oldReader io.Reader, newWriter io.Writer, patchReader io.Reader) (err error) {
+	return patch.Patch(oldReader, newWriter, patchReader)
+}
diff --git a/patch.go b/patch/patch.go
similarity index 83%
rename from patch.go
rename to patch/patch.go
index f2a0dde..d3ff8f4 100644
--- a/patch.go
+++ b/patch/patch.go
@@ -1,4 +1,4 @@
-package bsdiff
+package patch
 
 import (
 	"compress/bzip2"
@@ -6,6 +6,7 @@ import (
 	"io/ioutil"
 	"log"
 
+	"github.com/icedream/go-bsdiff/internal"
 	"github.com/icedream/go-bsdiff/internal/native"
 )
 
@@ -15,7 +16,7 @@ func Patch(oldReader io.Reader, newWriter io.Writer, patchReader io.Reader) (err
 		return
 	}
 
-	newLen, err := readHeader(patchReader)
+	newLen, err := internal.ReadHeader(patchReader)
 	if err != nil {
 		return
 	}