Partial implementation of streamblock

2 files changed, 96 insertions, 0 deletions

diff --git a/src/lzssblock.nim b/src/lzssblock.nim
new file mode 100644
index 0000000..87b62a0
--- /dev/null
+++ b/src/lzssblock.nim
@@ -0,0 +1,32 @@
+# "à-la-gzip" 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 bitstream
+
+type LzssBlock* = object
+  discard
+
+proc readSerialised*(bitStream: BitStream): LzssBlock =
+  discard
+
+proc writeSerialisedTo*(lzssBlock: LzssBlock, bitStream: BitStream) =
+  discard
+
+proc readRaw*(bitStream: BitStream): LzssBlock =
+  discard
+
+proc writeRawTo*(lzssBlock: LzssBlock, bitStream: BitStream) =
+  discard
diff --git a/src/streamblock.nim b/src/streamblock.nim
new file mode 100644
index 0000000..8d2b4b1
--- /dev/null
+++ b/src/streamblock.nim
@@ -0,0 +1,64 @@
+# "à-la-gzip" 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 sequtils
+import integers, bitstream, rawblock, lzssblock
+
+type BlockKind* = enum
+  uncompressed = 0b00'u8,
+  lzss = 0b01,
+  reserved1 = 0b10,
+  reserved2 = 0b11
+
+type StreamBlock* = object
+  last: bool
+  case kind: BlockKind
+    of uncompressed:
+      rawBlock: RawBlock
+    of lzss:
+      lzssBlock: LzssBlock
+    else:
+      discard
+
+proc readSerialised*(bitStream: BitStream): StreamBlock =
+  result.last = bitStream.readBool()
+  result.kind = bitStream.readBits(2, uint8).BlockKind
+  case result.kind:
+    of uncompressed: result.rawBlock = rawblock.readRaw(bitStream)
+    of lzss: result.lzssBlock = lzssblock.readRaw(bitStream)
+    else: raise newException(ValueError, "unhandled block type")
+
+proc writeSerialisedTo*(streamBlock: StreamBlock, bitStream: BitStream) =
+  bitStream.writeBool(streamBlock.last)
+  bitStream.writeBits(2, streamBlock.kind.uint8)
+  case streamBlock.kind:
+    of uncompressed: streamBlock.rawBlock.writeSerialisedTo(bitStream)
+    of lzss: streamBlock.lzssBlock.writeSerialisedTo(bitStream)
+    else: raise newException(ValueError, "unhandled block type")
+
+proc readRaw*(bitStream: BitStream, kind: BlockKind = uncompressed): StreamBlock =
+  result.kind = kind
+  case kind:
+    of uncompressed: result.rawBlock = rawblock.readRaw(bitStream)
+    of lzss: result.lzssBlock = lzssblock.readRaw(bitStream)
+    else: raise newException(ValueError, "unhandled block type")
+  result.last = bitStream.atEnd()
+
+proc writeRawTo*(streamBlock: StreamBlock, bitStream: BitStream) =
+  case streamBlock.kind:
+    of uncompressed: streamBlock.rawBlock.writeRawTo(bitStream)
+    of lzss: streamBlock.lzssBlock.writeRawTo(bitStream)
+    else: raise newException(ValueError, "unhandled block type")