From 6250518b6f1c1a91502c33a41abbdd60f895fc39 Mon Sep 17 00:00:00 2001
From: Zahary Karadjov <zahary@gmail.com>
Date: Wed, 31 Jul 2019 01:50:05 +0300
Subject: [PATCH] Stronger guarantees for write block sizes

Certain output streams such as compressors and ciphers may require
a certain block size on each write.
---
 faststreams/output_stream.nim | 19 ++++++++++---------
 1 file changed, 10 insertions(+), 9 deletions(-)

diff --git a/faststreams/output_stream.nim b/faststreams/output_stream.nim
index 0c62f15..5d6ac65 100644
--- a/faststreams/output_stream.nim
+++ b/faststreams/output_stream.nim
@@ -223,16 +223,17 @@ proc writeDataAsPages(s: OutputStreamVar, data: ptr byte, dataLen: int) =
     data = data
     dataLen = dataLen
 
-  if dataLen < s.maxWriteSize:
-    s.vtable.writePage(s, makeOpenArray(data, dataLen))
-    s.endPos += dataLen
-    return
+  if dataLen > s.pageSize:
+    if dataLen < s.maxWriteSize:
+      s.vtable.writePage(s, makeOpenArray(data, dataLen))
+      s.endPos += dataLen
+      return
 
-  while dataLen > s.pageSize:
-    s.vtable.writePage(s, makeOpenArray(data, s.pageSize))
-    data = shift(data, s.pageSize)
-    dec dataLen, s.pageSize
-    s.endPos += s.pageSize
+    while dataLen > s.pageSize:
+      s.vtable.writePage(s, makeOpenArray(data, s.pageSize))
+      data = shift(data, s.pageSize)
+      dec dataLen, s.pageSize
+      s.endPos += s.pageSize
 
   copyMem(s.cursor.head, data, dataLen)
   s.cursor.head = shift(s.cursor.head, dataLen)