From 5cc4256a931b98ea167291397421d0db60c5d40c Mon Sep 17 00:00:00 2001
From: pacien
Date: Sun, 2 Dec 2018 00:22:56 +0100
Subject: implement lzss block

---
 src/lzsshuffman/lzsshuffmandecoder.nim | 34 ++++++++++++++++++++++++++++++++++
 1 file changed, 34 insertions(+)
 create mode 100644 src/lzsshuffman/lzsshuffmandecoder.nim

(limited to 'src/lzsshuffman/lzsshuffmandecoder.nim')

diff --git a/src/lzsshuffman/lzsshuffmandecoder.nim b/src/lzsshuffman/lzsshuffmandecoder.nim
new file mode 100644
index 0000000..cd71914
--- /dev/null
+++ b/src/lzsshuffman/lzsshuffmandecoder.nim
@@ -0,0 +1,34 @@
+# gzip-like LZSS compressor
+# Copyright (C) 2018  Pacien TRAN-GIRARD
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Affero General Public License as
+# published by the Free Software Foundation, either version 3 of the
+# License, or (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU Affero General Public License for more details.
+#
+# You should have received a copy of the GNU Affero General Public License
+# along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+import lists
+import ../bitio/bitreader
+import ../lzss/listpolyfill, ../lzss/lzssnode, ../lzss/lzsschain
+import ../huffman/huffmantree, ../huffman/huffmandecoder
+import lzsshuffmansymbol
+
+proc readChain*(bitReader: BitReader, symbolDecoder, positionDecoder: HuffmanDecoder[uint16], maxDataByteLength: int): LzssChain =
+  var chain = lzssChain()
+  var (symbol, byteCursor) = (symbolDecoder.decode(bitReader).Symbol, 0)
+  while not symbol.isEndMarker():
+    if byteCursor > maxDataByteLength: raise newException(IOError, "lzss block too long")
+    if symbol.isCharacter():
+      chain.append(lzssCharacter(symbol.uint8))
+    else:
+      let position = positionDecoder.decode(bitReader)
+      chain.append(unpackLzssReference(symbol, position))
+    (symbol, byteCursor) = (symbolDecoder.decode(bitReader).Symbol, byteCursor + 1)
+  chain
-- 
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