From b55fcf3dc4c775ef35dce116ab23d35a5f9ff326 Mon Sep 17 00:00:00 2001
From: Joshua MacDonald <josh.macdonald@gmail.com>
Date: Sun, 25 Jan 2015 23:17:17 -0800
Subject: regtest.go tests a random stream and an offset copy

---
 xdelta3/go/src/xdelta/rstream.go | 56 ++++++++++++++++++++++++++++++++++++++++
 1 file changed, 56 insertions(+)
 create mode 100644 xdelta3/go/src/xdelta/rstream.go

(limited to 'xdelta3/go/src/xdelta/rstream.go')

diff --git a/xdelta3/go/src/xdelta/rstream.go b/xdelta3/go/src/xdelta/rstream.go
new file mode 100644
index 0000000..1666934
--- /dev/null
+++ b/xdelta3/go/src/xdelta/rstream.go
@@ -0,0 +1,56 @@
+package xdelta
+
+
+import (
+	"io"
+	"math/rand"
+)
+
+const (
+	blocksize = 16380  // A factor of 7
+)
+
+func WriteRstreams(seed, offset, len int64,
+	first, second io.WriteCloser) {
+	go writeOne(seed, 0, len, first)
+	go writeOne(seed, offset, len, second)
+}
+
+func writeOne(seed, offset, len int64, stream io.WriteCloser) {
+	if offset != 0 {
+		// Fill with other random data until the offset
+		writeRand(rand.New(rand.NewSource(^seed)),
+			offset, stream)
+	}
+	writeRand(rand.New(rand.NewSource(seed)),
+		len - offset, stream)
+	if err := stream.Close(); err != nil {
+		panic(err)
+	}
+}
+
+func writeRand(r *rand.Rand, len int64, s io.Writer) {
+	blk := make([]byte, blocksize)
+	for len > 0 {
+		fillRand(r, blk)
+		c := blocksize
+		if len < blocksize {
+			c = int(len)
+		}
+		if _, err := s.Write(blk[0:c]); err != nil {
+			panic(err)
+		}
+		len -= int64(c)
+	}
+}
+
+func fillRand(r *rand.Rand, blk []byte) {
+	for p := 0; p < blocksize; {
+		v := r.Int63()
+		for i := 7; i != 0; i-- {
+			blk[p] = byte(v)
+			p++
+			v >>= 8
+		}
+	}
+}
-- 
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