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

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

diff --git a/src/lzsshuffman/lzsshuffmansymbol.nim b/src/lzsshuffman/lzsshuffmansymbol.nim
new file mode 100644
index 0000000..cfd3fe4
--- /dev/null
+++ b/src/lzsshuffman/lzsshuffmansymbol.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 ../lzss/lzssnode, ../lzss/lzssencoder
+
+type Symbol* = uint16
+
+const endSymbol* = 256.Symbol
+
+proc isEndMarker*(symbol: Symbol): bool =
+  symbol == endSymbol
+
+proc isCharacter*(symbol: Symbol): bool =
+  symbol < endSymbol
+
+proc unpackLzssReference*(symbol: Symbol, position: uint16): LzssNode =
+  lzssReference(symbol.int - endSymbol.int - 1 + matchGroupLength, position.int)  
+
+proc shiftLzssLength*(length: int): uint16 =
+  (length + endSymbol.int + 1 - matchGroupLength).uint16
-- 
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