refs #35 Lynon builtin compression

lynglib/src/commonMain/kotlin/net/sergeych/lynon/BitInput.kt

@@ -1,36 +1,9 @@
 package net.sergeych.lynon
 
-abstract class BitInput {
+interface BitInput {
 
-    data class DataByte(val data: Int,val bits: Int)
 
-    /**
+    fun getBitOrNull(): Int?
-     * Return next byte, int in 0..255 range, or -1 if end of stream reached
-     */
-    abstract fun getByte(): DataByte
-
-    private var accumulator = 0
-
-    var isEndOfStream: Boolean = false
-        private set
-
-    private var mask = 0
-
-    fun getBitOrNull(): Int? {
-        if (isEndOfStream) return null
-        if (mask == 0) {
-            val ab = getByte()
-            accumulator = ab.data
-            if (accumulator == -1) {
-                isEndOfStream = true
-                return null
-            }
-            mask = 1 shl (ab.bits - 1)
-        }
-        val result = if (0 == accumulator and mask) 0 else 1
-        mask = mask shr 1
-        return result
-    }
 
     fun getBitsOrNull(count: Int): ULong? {
         var result = 0UL
@@ -54,8 +27,11 @@ abstract class BitInput {
         return getBitOrNull() ?: throw IllegalStateException("Unexpected end of stream")
     }
 
-    fun unpackUnsigned(): ULong {
+    fun unpackUnsigned(): ULong =
-        val tetrades = getBits(4).toInt()
+        unpackUnsignedOrNull() ?: throw IllegalStateException("Unexpected end of stream")
+
+    fun unpackUnsignedOrNull(): ULong? {
+        val tetrades = getBitsOrNull(4)?.toInt() ?: return null
         var result = 0UL
         var shift = 0
         for (i in 0.. tetrades) {
@@ -84,5 +60,27 @@ abstract class BitInput {
         }
         return result
     }
+
+
+    fun decompress(): ByteArray = decompressOrNull() ?: throw DecompressionException("Unexpected end of stream")
+
+    fun decompressOrNull(): ByteArray? {
+        val originalSize = unpackUnsignedOrNull()?.toInt() ?: return null
+        return if( getBit() == 1) {
+            // data is compressed
+//            val expectedCRC = getBits(32).toUInt()
+            val method = getBits(2).toInt()
+            if( method != 0) throw DecompressionException("Unknown compression method")
+            LZW.decompress(this, originalSize).asByteArray()
+        }
+        else {
+            getBytes(originalSize) ?: throw DecompressionException("Unexpected end of stream in uncompressed data")
+        }
+    }
+
+    @Suppress("unused")
+    fun decompressStringOrNull(): String? = decompressOrNull()?.decodeToString()
+
+    fun decompressString(): String = decompress().decodeToString()
 }
 

lynglib/src/commonMain/kotlin/net/sergeych/lynon/BitList.kt

@@ -0,0 +1,34 @@
+package net.sergeych.lynon
+
+@Suppress("unused")
+interface BitList {
+    operator fun get(bitIndex: Long): Int
+    operator fun set(bitIndex: Long,value: Int)
+    val size: Long
+    val indices: LongRange
+
+    fun toInput(): BitInput = object : BitInput {
+        private var index = 0L
+
+        override fun getBitOrNull(): Int? =
+            if( index < size) this@BitList[index++]
+            else null
+    }
+}
+
+fun bitListOf(vararg bits: Int): BitList {
+    return if( bits.size > 64) {
+        BitArray.ofBits(*bits)
+    }
+    else
+        TinyBits.of(*bits)
+}
+
+@Suppress("unused")
+fun bitListOfSize(sizeInBits: Long): BitList {
+    return if( sizeInBits > 64) {
+        BitArray.withBitSize(sizeInBits)
+    }
+    else
+        TinyBits()
+}

lynglib/src/commonMain/kotlin/net/sergeych/lynon/BitOutput.kt

@@ -1,27 +1,6 @@
 package net.sergeych.lynon
 
-abstract class BitOutput {
+interface BitOutput {
-
-    abstract fun outputByte(byte: UByte)
-
-    private var accumulator = 0
-
-    /**
-     * Number of bits in accumulator. After output is closed by [close] this value is
-     * not changed and represents the number of bits in the last byte; this should
-     * be used to properly calculate end of the bit stream
-     */
-    private var accumulatorBits = 0
-        private set
-
-    /**
-     * When [close] is called, represents the number of used bits in the last byte;
-     * bits after this number are the garbage and should be ignored
-     */
-    val lastByteBits: Int get() {
-        if( !isClosed ) throw IllegalStateException("BitOutput is not closed")
-        return accumulatorBits
-    }
 
     fun putBits(bits: ULong, count: Int) {
         require(count <= 64)
@@ -41,13 +20,11 @@ abstract class BitOutput {
         }
     }
 
-    fun putBit(bit: Int) {
+    fun putBit(bit: Int)
-        accumulator = (accumulator shl 1) or bit
+
-        if (++accumulatorBits >= 8) {
+    fun putBits(bitList: BitList) {
-            outputByte(accumulator.toUByte())
+        for (i in bitList.indices)
-            accumulator = accumulator shr 0
+            putBit(bitList[i])
-            accumulatorBits = 0
-        }
     }
 
     fun packUnsigned(value: ULong) {
@@ -71,23 +48,57 @@ abstract class BitOutput {
         }
     }
 
-    var isClosed = false
-        private set
-
-    fun close(): BitOutput {
-        if (!isClosed) {
-            if (accumulatorBits > 0) {
-                outputByte(accumulator.toUByte())
-            } else accumulatorBits = 8
-            isClosed = true
-        }
-        return this
-    }
-
     fun putBytes(data: ByteArray) {
         for (b in data) {
             putBits(b.toULong(), 8)
         }
     }
 
+
+    /**
+     * Create compressed record with content and size check. Compression works with _bytes_.
+     *
+     * Structure:
+     *
+     * | size | meaning                                          |
+     * |------|--------------------------------------------------|
+     * | packed unsigned | size of uncompressed content in bytes |
+     * | 1               | 0 - not compressed, 1 - compressed |
+     *
+     * __If compressed__, then:
+     *
+     * | size | meaning                              |
+     * |------|--------------------------------------|
+     * |  2   | 00 - LZW, other combinations reserved|
+     *
+     * After this header compressed bits follow.
+     *
+     * __If not compressed,__ then source data follows as bit stream.
+     *
+     * Compressed block overhead is 3 bits, uncompressed 1.
+     */
+    fun compress(source: ByteArray) {
+        // size
+        packUnsigned(source.size.toULong())
+        // check compression is effective?
+        val compressed = LZW.compress(source.asUByteArray())
+        // check that compression is effective including header bits size:
+        if( compressed.size + 2 < source.size * 8L) {
+            println("write compressed")
+            putBit(1)
+            // LZW algorithm
+            putBits(0, 2)
+            // compressed data
+            putBits(compressed)
+        }
+        else {
+            putBit(0)
+            putBytes(source)
+        }
+    }
+
+    fun compress(source: String) {
+        compress(source.encodeToByteArray())
+    }
+
 }

lynglib/src/commonMain/kotlin/net/sergeych/lynon/DecompressionException.kt

@@ -0,0 +1,3 @@
+package net.sergeych.lynon
+
+class DecompressionException(message: String) : IllegalArgumentException(message) {}

lynglib/src/commonMain/kotlin/net/sergeych/lynon/LynonDecoder.kt

@@ -28,10 +28,10 @@ open class LynonDecoder(val bin: BitInput,val settings: LynonSettings = LynonSet
         return decodeCached { type.deserialize(scope, this) }
     }
 
-    fun unpackBinaryData(): ByteArray? {
+    fun unpackBinaryData(): ByteArray = bin.decompress()
-        val size = bin.unpackUnsigned()
+
-        return bin.getBytes(size.toInt())
+    @Suppress("unused")
-    }
+    fun unpackBinaryDataOrNull(): ByteArray? = bin.decompressOrNull()
 
     fun unpackBoolean(): Boolean {
         return bin.getBit() == 1

lynglib/src/commonMain/kotlin/net/sergeych/lynon/LynonEncoder.kt

@@ -29,8 +29,7 @@ open class LynonEncoder(val bout: BitOutput,val settings: LynonSettings = LynonS
     }
 
     fun encodeBinaryData(data: ByteArray) {
-        bout.packUnsigned(data.size.toULong())
+        bout.compress(data)
-        bout.putBytes(data)
     }
 
     fun encodeSigned(value: Long) {

lynglib/src/commonMain/kotlin/net/sergeych/lynon/MemoryBitInput.kt

@@ -1,20 +1,39 @@
 package net.sergeych.lynon
 
-class MemoryBitInput(val packedBits: UByteArray,val lastByteBits: Int): BitInput() {
 
-    constructor(bout: MemoryBitOutput): this(bout.toUByteArray(), bout.lastByteBits)
+class MemoryBitInput(val packedBits: UByteArray, val lastByteBits: Int) : BitInput {
+
+    constructor(ba: BitArray) : this(ba.bytes, ba.lastByteBits) {}
+    constructor(mba: MemoryBitOutput) : this(mba.toBitArray()) {}
 
     private var index = 0
 
-    override fun getByte(): DataByte {
+    /**
-        return if( index < packedBits.size ) {
+     * Return next byte, int in 0..255 range, or -1 if end of stream reached
-            DataByte(
+     */
-                packedBits[index++].toInt(),
+    private var accumulator = 0
-                if( index == packedBits.size ) lastByteBits else 8
+
-            )
+    private var isEndOfStream: Boolean = false
-        } else {
+        private set
-            DataByte(-1,0)
+
+    private var mask = 0
+
+    override fun getBitOrNull(): Int? {
+        if (isEndOfStream) return null
+        if (mask == 0) {
+            if (index < packedBits.size) {
+                accumulator = packedBits[index++].toInt()
+                val n = if (index == packedBits.size) lastByteBits else 8
+                mask = 1 shl (n - 1)
+            } else {
+                isEndOfStream = true
+                return null
+            }
         }
+        val result = if (0 == accumulator and mask) 0 else 1
+        mask = mask shr 1
+        return result
     }
 
+
 }

lynglib/src/commonMain/kotlin/net/sergeych/lynon/MemoryBitOutput.kt

@@ -1,14 +1,135 @@
 package net.sergeych.lynon
 
-class MemoryBitOutput: BitOutput() {
+import kotlin.math.min
-    private val buffer = mutableListOf<UByte>()
 
-    fun toUByteArray(): UByteArray {
+/**
-        close()
+ * BitList implementation as fixed suze array of bits; indexing works exactly same as if
-        return buffer.toTypedArray().toUByteArray()
+ * [MemoryBitInput] is used with [MemoryBitInput.getBit].
+ */
+class BitArray(val bytes: UByteArray, val lastByteBits: Int) : BitList {
+
+    val bytesSize: Int get() = bytes.size
+    override val size by lazy { bytes.size * 8L - (8 - lastByteBits) }
+
+    override val indices by lazy { 0..<size }
+
+    /**
+     * @return [BitInput] that can be used to read from this array
+     */
+    fun toBitInput(): BitInput = MemoryBitInput(bytes, lastByteBits)
+
+    private fun getIndexAndMask(bitIndex: Long): Pair<Int, Int> {
+        val byteIndex = (bitIndex / 8).toInt()
+        if (byteIndex !in bytes.indices)
+            throw IndexOutOfBoundsException("$bitIndex is out of bounds")
+        val i = (bitIndex % 8).toInt()
+        return byteIndex to (
+                if (byteIndex == bytes.lastIndex) {
+                    if (i >= lastByteBits)
+                        throw IndexOutOfBoundsException("$bitIndex is out of bounds (last)")
+                    1 shl (lastByteBits - i - 1)
+                } else {
+                    1 shl (7 - i)
+                }
+                )
     }
 
-    override fun outputByte(byte: UByte) {
+    override operator fun get(bitIndex: Long): Int =
+        getIndexAndMask(bitIndex).let { (byteIndex, mask) ->
+            if (bytes[byteIndex].toInt() and mask == 0) 0 else 1
+        }
+
+    override operator fun set(bitIndex: Long, value: Int) {
+        require(value == 0 || value == 1)
+        val (byteIndex, mask) = getIndexAndMask(bitIndex)
+        if (value == 1)
+            bytes[byteIndex] = bytes[byteIndex] or mask.toUByte()
+        else
+            bytes[byteIndex] = bytes[byteIndex] and mask.inv().toUByte()
+    }
+
+    override fun toString(): String {
+        val result = StringBuilder()
+        val s = min(size, 64)
+        for (i in 0..<s) result.append(this[i])
+        if (s < size) result.append("…")
+        return result.toString()
+    }
+
+    companion object {
+
+        fun withBitSize(size: Long): BitArray {
+            val byteSize = ((size + 7) / 8).toInt()
+            val lastByteBits = size % 8
+            return BitArray(UByteArray(byteSize), lastByteBits.toInt())
+        }
+
+        fun ofBits(vararg bits: Int): BitArray {
+            return withBitSize(bits.size.toLong()).apply {
+                for (i in bits.indices) {
+                    this[i.toLong()] = bits[i]
+                }
+            }
+        }
+    }
+
+}
+
+class MemoryBitOutput : BitOutput {
+    private val buffer = mutableListOf<UByte>()
+
+    private var accumulator = 0
+
+    /**
+     * Number of bits in accumulator. After output is closed by [close] this value is
+     * not changed and represents the number of bits in the last byte; this should
+     * be used to properly calculate end of the bit stream
+     */
+    private var accumulatorBits = 0
+        private set
+
+//    /**
+//     * When [close] is called, represents the number of used bits in the last byte;
+//     * bits after this number are the garbage and should be ignored
+//     */
+//    val lastByteBits: Int
+//        get() {
+//            if (!isClosed) throw IllegalStateException("BitOutput is not closed")
+//            return accumulatorBits
+//        }
+
+    override fun putBit(bit: Int) {
+        accumulator = (accumulator shl 1) or bit
+        if (++accumulatorBits >= 8) {
+            outputByte(accumulator.toUByte())
+            accumulator = accumulator shr 8
+            accumulatorBits = 0
+        }
+    }
+
+    var isClosed = false
+        private set
+
+    fun close(): BitArray {
+        if (!isClosed) {
+            if (accumulatorBits > 0) {
+                outputByte(accumulator.toUByte())
+            } else accumulatorBits = 8
+            isClosed = true
+        }
+        return toBitArray()
+    }
+
+    fun toBitArray(): BitArray {
+        if (!isClosed) {
+            close()
+        }
+        return BitArray(buffer.toTypedArray().toUByteArray(), accumulatorBits)
+    }
+
+    fun toBitInput(): BitInput = toBitArray().toBitInput()
+
+    private fun outputByte(byte: UByte) {
         buffer.add(byte)
     }
 }

lynglib/src/commonMain/kotlin/net/sergeych/lynon/TinyBits.kt

@@ -0,0 +1,71 @@
+package net.sergeych.lynon
+
+
+/**
+ * Bit size-aware code, short [BitList] implementation, up to 64 bits (efficiency tradeoff).
+ * E.g `Bits(0, 3) != Bits(0, 2). For longer, use [BitArray].
+ *
+ * Note that [bitListOf] creates [TinyBits] when possible.
+ */
+class TinyBits(initValue: ULong = 0U, override val size: Long = 0): BitList {
+
+    private var bits: ULong = initValue
+
+    constructor(value: ULong, size: Int): this(value, size.toLong()) {}
+
+    override val indices: LongRange by lazy { 0..<size }
+
+    override operator fun get(bitIndex: Long): Int {
+        if( bitIndex !in indices) throw IndexOutOfBoundsException("index out of bounds: $bitIndex")
+        val mask = 1UL shl (size - bitIndex - 1).toInt()
+        return if (bits and mask != 0UL) 1 else 0
+    }
+
+    override fun set(bitIndex: Long, value: Int) {
+        val mask = 1UL shl (size - bitIndex - 1).toInt()
+        if( value == 1)
+            bits = bits or mask
+        else
+            bits = bits and mask.inv()
+    }
+
+    override fun toString(): String {
+        val result = StringBuilder()
+        for (i in 0..<size) result.append(this[i])
+        return result.toString()
+    }
+
+    val value by ::bits
+
+    /**
+     * Add bit shifting value to the left and return _new instance_
+     */
+    fun insertBit(bit: Int): TinyBits {
+        return TinyBits((bits shl 1) or bit.toULong(), size + 1)
+    }
+
+    override fun equals(other: Any?): Boolean {
+        if (this === other) return true
+        if (other == null || this::class != other::class) return false
+
+        other as TinyBits
+
+        if (size != other.size) return false
+        if (bits != other.bits) return false
+
+        return true
+    }
+
+    override fun hashCode(): Int {
+        var result = size.hashCode()
+        result = 31 * result + bits.hashCode()
+        return result
+    }
+
+
+    companion object {
+        fun of(vararg bits: Int): TinyBits {
+            return TinyBits(0UL, bits.size).apply { bits.forEachIndexed { i, v -> this[i.toLong()] = v } }
+        }
+    }
+}

lynglib/src/commonMain/kotlin/net/sergeych/lynon/huffman.kt

@@ -0,0 +1,244 @@
+package net.sergeych.lynon
+
+import net.sergeych.collections.SortedList
+
+/**
+ * Experimental, reference implementation of Huffman trees and encoding.
+ *
+ * This is a reference huffman encoding implementation not yet ready;
+ * it was used to experiment with LZW, at the moment, LZW won the competition
+ * for compressed module format for its speed and sufficiently small size/
+ *
+ * This is byte-based compressor which makes it not too interesting.
+ *
+ * TODO: convert to use various source dictionary
+ *
+ * reason: version thant compress bytes is not too interesting; particular alphabets
+ * are often longer than byte bits and are often sparse, that requires another
+ * codes serialization implementation
+ */
+object Huffman {
+
+    sealed class Node(val freq: Int) : Comparable<Node> {
+        override fun compareTo(other: Node): Int {
+            return freq.compareTo(other.freq)
+        }
+
+        abstract fun decode(bin: BitInput): Int?
+
+        class Leaf(val value: Int, freq: Int) : Node(freq) {
+            override fun toString(): String {
+                return "[$value:$freq]"
+            }
+
+            override fun decode(bin: BitInput): Int {
+                return value//.also { println(": ${Char(value)}") }
+            }
+        }
+
+        class Internal(val left: Node, val right: Node) : Node(left.freq + right.freq) {
+            override fun toString(): String {
+                return "[${left.freq}<- :<$freq>: ->${right.freq}]"
+            }
+
+            override fun decode(bin: BitInput): Int? {
+                return when (bin.getBitOrNull().also { print("$it") }) {
+                    1 -> left.decode(bin)
+                    0 -> right.decode(bin)
+                    else -> null
+                }
+            }
+        }
+    }
+
+    data class Code(val symbol: Int, val bits: TinyBits) {
+
+        val size by bits::size
+
+        override fun toString(): String {
+            return "[${Char(symbol)}:$size:$bits]"
+        }
+
+    }
+
+    private fun generateCanonicCodes(tree: Node): List<Code?> {
+        val codes = MutableList<Code?>(256) { null }
+
+        fun traverse(node: Node, code: TinyBits) {
+            when (node) {
+                is Node.Leaf ->
+                    codes[node.value] = (Code(node.value, code))
+
+                is Node.Internal -> {
+                    traverse(node.left, code.insertBit(1))
+                    traverse(node.right, code.insertBit(0))
+                }
+            }
+        }
+        traverse(tree, TinyBits())
+
+        return makeCanonical(codes)
+    }
+
+    private fun makeCanonical(source: List<Code?>): List<Code?> {
+        val sorted = source.filterNotNull().sortedWith(canonicComparator)
+
+        val canonical = MutableList<Code?>(256) { null }
+
+        val first = sorted[0]
+        val prevValue = first.copy(bits = TinyBits(0UL, first.bits.size))
+        canonical[first.symbol] = prevValue
+        var prev = prevValue.bits
+
+        for (i in 1..<sorted.size) {
+            var bits = TinyBits(prev.value + 1U, prev.size)
+            val code = sorted[i]
+            while (code.bits.size > bits.size) {
+                bits = bits.insertBit(0)
+            }
+            canonical[code.symbol] = code.copy(bits = bits)//.also { println("$it") }
+            prev = bits
+        }
+        return canonical
+    }
+
+    private val canonicComparator = { a: Code, b: Code ->
+        if (a.bits.size == b.bits.size) {
+            a.symbol.compareTo(b.symbol)
+        } else {
+            a.bits.size.compareTo(b.bits.size)
+        }
+    }
+
+    private fun buildTree(data: UByteArray): Node {
+//        println(data.toDump())
+        val frequencies = Array(256) { 0 }
+        data.forEach { frequencies[it.toInt()]++ }
+
+        val list = SortedList<Node>(*frequencies.mapIndexed { index, i -> Node.Leaf(index, i) }.filter { it.freq > 0 }
+            .toTypedArray())
+
+        // build the tree
+        while (list.size > 1) {
+            val left = list.removeAt(0)
+            val right = list.removeAt(0)
+            list.add(Node.Internal(left, right))
+        }
+        return list[0]
+    }
+
+    fun decompressUsingCodes(bin: BitInput, codes: List<Code?>): UByteArray {
+        val result = mutableListOf<UByte>()
+        val table = codes.filterNotNull().associateBy { it.bits }
+
+        outer@ while (true) {
+            var input = TinyBits()
+            while (true) {
+                bin.getBitOrNull()?.let { input = input.insertBit(it) }
+                    ?: break@outer
+                val data = table[input]
+                if (data != null) {
+//                    println("Code found: ${data.bits} -> [${data.symbol.toChar()}]")
+                    result.add(data.symbol.toUByte())
+                    break
+                }
+            }
+        }
+        return result.toUByteArray()
+    }
+
+    private fun serializeCanonicCodes(bout: BitOutput, codes: List<Code?>) {
+        var minSize: Int? = null
+        var maxSize: Int? = null
+        for (i in 1..<codes.size) {
+            val s = codes[i]?.size?.toInt() ?: continue
+            if (minSize == null || s < minSize) minSize = s
+            if (maxSize == null || s > maxSize) maxSize = s
+        }
+        val size = maxSize!! - minSize!! + 1
+        val sizeInBits = sizeInBits(size)
+        bout.packUnsigned(minSize.toULong())
+        bout.packUnsigned(sizeInBits.toULong())
+        for (c in codes) {
+            if (c != null)
+                bout.putBits(c.bits.size.toInt() - minSize + 1, sizeInBits)
+            else
+                bout.putBits(0, sizeInBits)
+        }
+    }
+
+    fun deserializeCanonicCodes(bin: BitInput): List<Code?> {
+        val minSize = bin.unpackUnsigned().toInt()
+        val sizeInBits = bin.unpackUnsigned().toInt()
+        val sorted = mutableListOf<Code>().also { codes ->
+            for (i in 0..<256) {
+                val s = bin.getBits(sizeInBits).toInt()
+                if (s > 0) {
+                    codes.add(Code(i, TinyBits(0U, s - 1 + minSize)))
+                }
+            }
+        }.sortedWith(canonicComparator)
+
+        val result = MutableList<Code?>(256) { null }
+        var prev = sorted[0].copy(bits = TinyBits(0U, sorted[0].bits.size))
+        result[prev.symbol] = prev
+
+        for (i in 1..<sorted.size) {
+            val code = sorted[i]
+            var bits = TinyBits(prev.bits.value + 1u, prev.bits.size)
+            while (bits.size < code.bits.size) bits = bits.insertBit(0)
+            result[code.symbol] = code.copy(bits = bits).also {
+                prev = it
+            }
+        }
+        return result
+    }
+
+    fun compress(data: UByteArray): BitArray {
+
+        val root = buildTree(data)
+
+        val codes = generateCanonicCodes(root)
+
+        // serializa table
+
+        // test encode:
+        val bout = MemoryBitOutput()
+        serializeCanonicCodes(bout, codes)
+        for (i in data) {
+            val code = codes[i.toInt()]!!
+//            println(">> $code")
+            bout.putBits(code.bits)
+        }
+//        println(bout.toBitArray().bytes.toDump())
+        val compressed = bout.toBitArray()
+//        println("Size: ${compressed.bytes.size / data.size.toDouble() }")
+//        println("compression ratio: ${compressed.bytes.size / data.size.toDouble() }")
+
+        // test decompress
+//        val bin = MemoryBitInput(compressed)
+//        val codes2 = deserializeCanonicCodes(bin)
+//        for ((a, b) in codes.zip(codes2)) {
+//            if (a != b) {
+//                println("Codes mismatch: $a != $b")
+//                break
+//            }
+//        }
+//        require(codes == codes2)
+//        val result = decompressUsingCodes(bin, codes2)
+//
+////        println(result.toUByteArray().toDump())
+//        check(data contentEquals result.toUByteArray())
+//        if( !(data contentEquals result.toUByteArray()) )
+//            throw RuntimeException("Data mismatch")
+//        println(data.toDump())
+//
+        return compressed
+    }
+
+    fun decompress(bin: BitInput): UByteArray {
+        val codes = deserializeCanonicCodes(bin)
+        return decompressUsingCodes(bin, codes)
+    }
+
+}

lynglib/src/commonMain/kotlin/net/sergeych/lynon/lzw.kt

@@ -0,0 +1,128 @@
+package net.sergeych.lynon
+
+import net.sergeych.bintools.ByteChunk
+import kotlin.math.roundToInt
+
+/**
+ * LZW lightweight pure kotlin compression.
+ */
+object LZW {
+
+    val MAX_CODE_SIZE = 17
+    val STOP_CODE = (1 shl MAX_CODE_SIZE) - 1
+    val MAX_DICT_SIZE = (STOP_CODE * 0.92).roundToInt()
+
+
+    fun compress(input: ByteArray, bitOutput: BitOutput)
+        = compress(input.asUByteArray(), bitOutput)
+
+    /**
+     * Compresses the input string using LZW algorithm
+     * @param input The string to compress
+     * @return List of compressed codes
+     */
+    fun compress(input: UByteArray, bitOutput: BitOutput) {
+        // Initialize dictionary with all possible single characters
+        val dictionary = mutableMapOf<ByteChunk, Int>()
+        for (i in 0..255) {
+            // 23
+            dictionary[ByteChunk(ubyteArrayOf(i.toUByte()))] = i
+        }
+
+        var nextCode = 256
+        var current = ByteChunk(ubyteArrayOf())
+//            val result = mutableListOf<Int>()
+
+        for (char in input) {
+            val combined = current + char
+            if (dictionary.containsKey(combined)) {
+                current = combined
+            } else {
+                val size = sizeInBits(dictionary.size)
+                bitOutput.putBits(dictionary[current]!!, size)
+                if (dictionary.size >= MAX_DICT_SIZE) {
+                    bitOutput.putBits(STOP_CODE, size)
+                    dictionary.clear()
+                    nextCode = 256
+                    for (i in 0..255) {
+                        dictionary[ByteChunk(ubyteArrayOf(i.toUByte()))] = i
+                    }
+                } else
+                    dictionary[combined] = nextCode++
+                current = ByteChunk(ubyteArrayOf(char))
+            }
+        }
+
+        if (current.size > 0) {
+            val size = sizeInBits(dictionary.size)
+            bitOutput.putBits(dictionary[current]!!, size)
+        }
+    }
+
+    fun compress(input: UByteArray): BitArray {
+        return MemoryBitOutput().apply {
+            compress(input, this)
+        }.toBitArray()
+    }
+
+    /**
+     * Decompresses a list of LZW codes back to the original string. Note that usage of apriori existing
+     * size is crucial: it let repeal explosion style attacks.
+     *
+     * @param compressed The list of compressed codes
+     * @param resultSize The expected size of the decompressed string
+     *
+     * @throws DecompressionException if something goes wrong
+     * @return The decompressed string
+     */
+    fun decompress(compressed: BitInput, resultSize: Int): UByteArray {
+        // Initialize dictionary with all possible single characters
+        val dictionary = mutableMapOf<Int, UByteArray>()
+        for (i in 0..255) {
+            dictionary[i] = ubyteArrayOf(i.toUByte())
+        }
+
+        var nextCode = 256
+        val firstCode = compressed.getBits(9).toInt()
+        var previous = dictionary[firstCode]
+            ?: throw DecompressionException("Invalid first compressed code: $firstCode")
+        val result = mutableListOf<UByte>()
+        result += previous
+
+        while (result.size < resultSize) {
+            val codeSize = sizeInBits(nextCode + 1)
+            val code = compressed.getBitsOrNull(codeSize)?.toInt() ?: break
+
+            if (code == STOP_CODE) {
+                nextCode = 256
+                dictionary.clear()
+                for (i in 0..255)
+                    dictionary[i] = ubyteArrayOf(i.toUByte())
+                previous = dictionary[compressed.getBits(9).toInt()]!!
+            } else {
+
+                val current = if (code in dictionary) {
+                    dictionary[code]!!
+                } else if (code == nextCode) {
+                    // Special case for pattern like cScSc
+                    previous + previous[0]
+                } else {
+                    throw DecompressionException("Invalid compressed code: $code")
+                }
+
+                result += current
+                dictionary[nextCode++] = previous + current[0]
+                previous = current
+            }
+        }
+
+        if (result.size != resultSize)
+            throw DecompressionException("Decompressed size is not equal to expected: real/expected = ${result.size}/$resultSize")
+        return result.toTypedArray().toUByteArray()
+    }
+}
+
+
+private operator fun ByteChunk.plus(byte: UByte): ByteChunk {
+    return ByteChunk(data + byte)
+}

lynglib/src/commonMain/kotlin/net/sergeych/lynon/lzw0.kt

@@ -1,114 +0,0 @@
-package net.sergeych.lynon
-
-import net.sergeych.bintools.ByteChunk
-import kotlin.math.roundToInt
-
-/**
- * LZW compression algorithm: work in progress.
- *
- * Uses Lyng but input/output. Uses automatic code size.
- */
-class LZW {
-    companion object {
-
-        val MAX_CODE_SIZE = 17
-        val STOP_CODE = (1 shl MAX_CODE_SIZE) - 1
-        val MAX_DICT_SIZE = (STOP_CODE * 0.92).roundToInt()
-
-
-        /**
-         * Compresses the input string using LZW algorithm
-         * @param input The string to compress
-         * @return List of compressed codes
-         */
-        fun compress(input: UByteArray,bitOutput: BitOutput) {
-            // Initialize dictionary with all possible single characters
-            val dictionary = mutableMapOf<ByteChunk, Int>()
-            for (i in 0..255) {
-                // 23
-                dictionary[ByteChunk(ubyteArrayOf(i.toUByte()))] = i
-            }
-
-            var nextCode = 256
-            var current = ByteChunk(ubyteArrayOf())
-//            val result = mutableListOf<Int>()
-
-            for (char in input) {
-                val combined = current + char
-                if (dictionary.containsKey(combined)) {
-                    current = combined
-                } else {
-                    val size = sizeInBits(dictionary.size)
-                    bitOutput.putBits(dictionary[current]!!,size)
-                    if( dictionary.size >= MAX_DICT_SIZE ) {
-                        bitOutput.putBits(STOP_CODE,size)
-                        dictionary.clear()
-                        nextCode = 256
-                        for (i in 0..255) {
-                            dictionary[ByteChunk(ubyteArrayOf(i.toUByte()))] = i
-                        }
-                    }
-                    else
-                        dictionary[combined] = nextCode++
-                    current = ByteChunk(ubyteArrayOf(char))
-                }
-            }
-
-            if (current.size > 0) {
-                val size = sizeInBits(dictionary.size)
-                bitOutput.putBits(dictionary[current]!!,size)
-            }
-        }
-
-        /**
-         * Decompresses a list of LZW codes back to the original string
-         * @param compressed The list of compressed codes
-         * @return The decompressed string
-         */
-        fun decompress(compressed: BitInput): UByteArray {
-            // Initialize dictionary with all possible single characters
-            val dictionary = mutableMapOf<Int, UByteArray>()
-            for (i in 0..255) {
-                dictionary[i] = ubyteArrayOf(i.toUByte())
-            }
-
-            var nextCode = 256
-            var previous = dictionary[compressed.getBits(9).toInt()]!!
-            val result = mutableListOf<UByte>()
-
-            while( !compressed.isEndOfStream ) {
-                val codeSize = sizeInBits(nextCode + 1)
-                val code = compressed.getBitsOrNull(codeSize)?.toInt() ?: break
-
-                if( code == STOP_CODE ) {
-                    nextCode = 256
-                    dictionary.clear()
-                    for (i in 0..255)
-                        dictionary[i] = ubyteArrayOf(i.toUByte())
-                    previous = dictionary[compressed.getBits(9).toInt()]!!
-                }
-                else {
-
-                    val current = if (code in dictionary) {
-                        dictionary[code]!!
-                    } else if (code == nextCode) {
-                        // Special case for pattern like cScSc
-                        previous + previous[0]
-                    } else {
-                        throw IllegalArgumentException("Invalid compressed code: $code")
-                    }
-
-                    result += current
-                    dictionary[nextCode++] = previous + current[0]
-                    previous = current
-                }
-            }
-
-            return result.toTypedArray().toUByteArray()
-        }
-    }
-}
-
-private operator fun ByteChunk.plus(byte: UByte): ByteChunk {
-    return ByteChunk(data + byte)
-}

lynglib/src/commonMain/kotlin/net/sergeych/lynon/tools.kt

@@ -11,5 +11,5 @@ class LynonPacker(bout: MemoryBitOutput = MemoryBitOutput(), settings: LynonSett
  * Variant of [LynonDecoder] that reads from a given `source` using [MemoryBitInput]
  */
 class LynonUnpacker(source: BitInput) : LynonDecoder(source) {
-    constructor(packer: LynonPacker) : this(MemoryBitInput(packer.bout as MemoryBitOutput))
+    constructor(packer: LynonPacker) : this((packer.bout as MemoryBitOutput).toBitInput())
 }

lynglib/src/jvmTest/kotlin/LynonTests.kt

@@ -6,7 +6,7 @@ import net.sergeych.lynon.*
 import java.nio.file.Files
 import java.nio.file.Path
 import kotlin.test.Test
-
+import kotlin.test.assertContentEquals
 class LynonTests {
 
     @Test
@@ -210,11 +210,13 @@ class LynonTests {
         assertEquals(null, bin.getBitsOrNull(3))
     }
 
+
+    val original = Files.readString(Path.of("../sample_texts/dikkens_hard_times.txt"))
+
     @Test
     fun testLzw() {
         // Example usage
 //        val original = "TOBEORNOTTOBEORTOBEORNOT"
-        val original = Files.readString(Path.of("../sample_texts/dikkens_hard_times.txt"))
 //        println("Original: $original")
         println("Length: ${original.length}")
 
@@ -222,14 +224,112 @@ class LynonTests {
         val out = MemoryBitOutput()
         LZW.compress(original.encodeToByteArray().toUByteArray(), out)
 //        println("\nCompressed codes: ${out.toUByteArray().toDump()}")
-        println("Number of codes: ${out.toUByteArray().size}")
+        println("Number of codes: ${out.toBitArray().bytesSize}")
-
+        println("Copression rate: ${out.toBitArray().bytesSize.toDouble() / original.length.toDouble()}")
 //        // Decompress
-        val decompressed = LZW.decompress(MemoryBitInput(out)).toByteArray().decodeToString()
+        val decompressed = LZW.decompress(MemoryBitInput(out), original.length).toByteArray().decodeToString()
 //        println("\nDecompressed: $decompressed")
         println("Length: ${decompressed.length}")
 
         // Verification
         println("\nOriginal and decompressed match: ${original == decompressed}")
+        assertEquals(original, decompressed)
     }
-}
+
+    @Test
+    fun testTinyBits() {
+        var a0 = TinyBits()
+
+        assertEquals(a0, a0)
+        a0 = a0.insertBit(0)
+        a0 = a0.insertBit(1)
+        a0 = a0.insertBit(1)
+        a0 = a0.insertBit(1)
+        a0 = a0.insertBit(0)
+        a0 = a0.insertBit(1)
+//        println(a0)
+        assertEquals("011101", a0.toString())
+        val bin = MemoryBitInput(MemoryBitOutput().apply { putBits(a0) })
+        var result = TinyBits()
+        for( i in a0.indices)  result = result.insertBit(bin.getBit())
+        assertEquals(a0, result)
+    }
+
+    @Test
+    fun testHuffman() {
+        val x = original.encodeToByteArray().toUByteArray()
+//        val x ="hello, world!".toByteArray().asUByteArray()// original.encodeToByteArray().toUByteArray()
+        println("Original : ${x.size}")
+        val lzw = LZW.compress(x).bytes
+        println("LZW      : ${lzw.size}")
+        val ba = Huffman.compress(x)
+        val huff = ba.bytes
+        println("Huffman  : ${huff.size}")
+        val lzwhuff = Huffman.compress(lzw).bytes
+        println("LZW+HUFF : ${lzwhuff.size}")
+        val compressed = Huffman.compress(x)
+        val decompressed = Huffman.decompress(compressed.toBitInput())
+        assertContentEquals(x, decompressed)
+    }
+
+    @Test
+    fun testBitListSmall() {
+        var t = TinyBits()
+        for( i in listOf(1, 1, 0, 1, 0, 0, 0, 1, 1, 1, 1, 0, 1) )
+            t = t.insertBit(i)
+        assertEquals(1, t[0])
+        assertEquals(1, t[1])
+        assertEquals(0, t[2])
+        assertEquals("1101000111101",t.toString())
+        t[0] = 0
+        t[1] = 0
+        t[2] = 1
+        assertEquals("0011000111101",t.toString())
+        t[12] = 0
+        t[11] = 1
+        assertEquals("0011000111110",t.toString())
+    }
+
+    @Test
+    fun testBitListSerialization() {
+        // this also tests bitArray with first and last bytes
+        val bout = MemoryBitOutput()
+        assertEquals("1101", bitListOf(1, 1, 0, 1).toString())
+        bout.putBits(bitListOf(1, 1, 0, 1))
+        bout.putBits(bitListOf( 0, 0))
+        bout.putBits(bitListOf( 0, 1, 1, 1, 1, 0, 1))
+        val x = bout.toBitArray()
+        assertEquals("1101000111101",x.toString())
+    }
+
+
+    @Test
+    fun testCompressionWithOffsets() {
+        val src = "to be or not to be or not to be or not to be or not to be"
+        val bout = MemoryBitOutput()
+        bout.packUnsigned(1571UL)
+        LZW.compress(src.encodeToByteArray(), bout)
+        bout.packUnsigned(157108UL)
+        val bin = bout.toBitInput()
+        assertEquals(1571UL, bin.unpackUnsigned())
+        assertEquals(src, LZW.decompress(bin, src.length).asByteArray().decodeToString())
+        assertEquals(157108UL, bin.unpackUnsigned())
+    }
+
+    @Test
+    fun testCompressionRecord() {
+        val bout = MemoryBitOutput()
+        val src = "to be or not to be or not to be or not to be or not to be"
+        val src2 = "to be or not to be"
+        val src3 = "ababababab"
+        bout.compress(src)
+        bout.compress(src2)
+        bout.compress(src3)
+        val bin = bout.toBitInput()
+        assertEquals(src, bin.decompressString())
+        assertEquals(src2, bin.decompressString())
+        assertEquals(src3, bin.decompressString())
+    }
+
+}
+