From 1b1de0ebeb89059db28ed554bdf251db9e26a4075ccb31352824beb3ff131b5f Mon Sep 17 00:00:00 2001
From: Sergey Matveev <stargrave@stargrave.org>
Date: Sat, 15 Feb 2025 11:42:57 +0300
Subject: [PATCH] Tiny optimisation

---
 go/blob.go               | 4 ++++
 go/cm/enc/chapoly/dem.go | 2 +-
 2 files changed, 5 insertions(+), 1 deletion(-)

diff --git a/go/blob.go b/go/blob.go
index 8f1c71c..ee45abb 100644
--- a/go/blob.go
+++ b/go/blob.go
@@ -82,6 +82,10 @@ func NewBlobDecoder(r io.Reader, maxChunkLen int64) (*BlobDecoder, error) {
 	return &BlobDecoder{d: d, ChunkLen: chunkLen}, nil
 }
 
+func (d *BlobDecoder) SetReadBuf(buf []byte) {
+	d.d.readBuf = buf
+}
+
 // Get the next chunk of the BLOB. Last one may be smaller size than the
 // ChunkLen. When BLOB is finished, io.EOF is returned with nil chunk.
 func (d *BlobDecoder) Next() (chunk []byte, err error) {
diff --git a/go/cm/enc/chapoly/dem.go b/go/cm/enc/chapoly/dem.go
index c2ec534..021a2b6 100644
--- a/go/cm/enc/chapoly/dem.go
+++ b/go/cm/enc/chapoly/dem.go
@@ -159,8 +159,8 @@ func do(
 		if seal {
 			n, errR = io.ReadFull(r, j.buf[PadLen:PadLen+ChunkLen])
 		} else {
+			blobDecoder.SetReadBuf(j.buf)
 			chunk, errR = blobDecoder.Next()
-			copy(j.buf, chunk)
 			n = len(chunk)
 			j.buf = j.buf[:n]
 		}
-- 
2.48.1