implement lzss encoding

1 files changed, 39 insertions, 0 deletions

diff --git a/src/lzssnode.nim b/src/lzssnode.nim
new file mode 100644
index 0000000..de5958d
--- /dev/null
+++ b/src/lzssnode.nim
@@ -0,0 +1,39 @@
+# 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/>.
+
+type LzssNodeKind* = enum
+  character,
+  reference
+
+type LzssNode* = object
+  case kind*: LzssNodeKind
+    of character:
+      character*: uint8
+    of reference:
+      length*: int
+      relativePos*: int
+
+proc lzssCharacter*(value: uint8): LzssNode =
+  LzssNode(kind: character, character: value)
+
+proc lzssReference*(length, relativePos: int): LzssNode =
+  LzssNode(kind: reference, length: length, relativePos: relativePos)
+
+proc `==`*(a, b: LzssNode): bool =
+  if a.kind != b.kind: return false
+  case a.kind:
+    of character: a.character == b.character
+    of reference: a.length == b.length and a.relativePos == b.relativePos