support for serialized frames

src/commonMain/kotlin/net.sergeych.bintools/CRC.kt

@@ -0,0 +1,51 @@
+@file:OptIn(ExperimentalUnsignedTypes::class)
+
+package net.sergeych.bintools
+
+/**
+ * Common interfacte for all CRC variants. See [crc16], [crc32] and [crc8] for useful shortcuts.
+ */
+interface CRC<T> {
+    val lookupTable: List<T>
+    val value: T
+
+    fun update(inputs: UByteArray)
+    fun reset()
+
+    fun update(input: UByte) {
+        update(ubyteArrayOf(input))
+    }
+
+    fun update(inputs: ByteArray) {
+        update(inputs.toUByteArray())
+    }
+
+    companion object {
+        /**
+         * Calculate crc8 for a data array using a given polynomial (uses CRC8-Bluetooth's polynomial by default)
+         */
+        fun crc8(data: ByteArray, polynomial: UByte = 0xA7.toUByte()): UByte =
+            CRC8(polynomial).also { it.update(data) }.value
+
+        /**
+         * Calculate CRC16 for a data array using a given polynomial (CRC16-CCITT polynomial (0x1021) by default)
+         */
+        fun crc16(data: ByteArray, polynomial: UShort = 0x1021.toUShort()): UShort =
+            CRC16(polynomial).also { it.update(data) }.value
+
+        /**
+         * Calculate crc32 for a given data and polynomial (using CRC32 polynomial by default)
+         */
+        fun crc32(data: ByteArray, polynomial: UInt = 0x04C11DB7.toUInt()): UInt =
+            CRC32(polynomial).also { it.update(data) }.value
+    }
+}
+
+infix fun UShort.shl(bitCount: Int): UShort = (this.toUInt() shl bitCount).toUShort()
+infix fun UShort.shr(bitCount: Int): UShort = (this.toUInt() shr bitCount).toUShort()
+
+infix fun UByte.shl(bitCount: Int): UByte = (this.toUInt() shl bitCount).toUByte()
+infix fun UByte.shr(bitCount: Int): UByte = (this.toUInt() shr bitCount).toUByte()
+
+fun UByte.toBigEndianUShort(): UShort = this.toUShort() shl 8
+fun UByte.toBigEndianUInt(): UInt = this.toUInt() shl 24

src/commonMain/kotlin/net.sergeych.bintools/CRC16.kt

@@ -0,0 +1,43 @@
+@file:OptIn(ExperimentalUnsignedTypes::class)
+
+package net.sergeych.bintools
+
+/**
+ * Class to conveniently calculate CRC-16. It uses the CRC16-CCITT polynomial (0x1021) by default
+ */
+class CRC16(val polynomial: UShort = 0x1021.toUShort()) : CRC<UShort> {
+    override val lookupTable: List<UShort> = (0 until 256).map { crc16(it.toUByte(), polynomial) }
+
+    override var value: UShort = 0.toUShort()
+        private set
+
+    override fun update(inputs: UByteArray) {
+        value = crc16(inputs, value)
+    }
+
+    override fun reset() {
+        value = 0.toUShort()
+    }
+
+    private fun crc16(inputs: UByteArray, initialValue: UShort = 0.toUShort()): UShort {
+        return inputs.fold(initialValue) { remainder, byte ->
+            val bigEndianInput = byte.toBigEndianUShort()
+            val index = (bigEndianInput xor remainder) shr 8
+            lookupTable[index.toInt()] xor (remainder shl 8)
+        }
+    }
+
+    private fun crc16(input: UByte, polynomial: UShort): UShort {
+        val bigEndianInput = input.toBigEndianUShort()
+
+        return (0 until 8).fold(bigEndianInput) { result, _ ->
+            val isMostSignificantBitOne = result and 0x8000.toUShort() != 0.toUShort()
+            val shiftedResult = result shl 1
+
+            when (isMostSignificantBitOne) {
+                true -> shiftedResult xor polynomial
+                false -> shiftedResult
+            }
+        }
+    }
+}

src/commonMain/kotlin/net.sergeych.bintools/CRC32.kt

@@ -0,0 +1,43 @@
+@file:OptIn(ExperimentalUnsignedTypes::class)
+
+package net.sergeych.bintools
+
+/**
+ *  Class to conveniently calculate CRC-32 using CRC32 polynomial (0x04C11DB7) by default
+ */
+class CRC32(val polynomial: UInt = 0x04C11DB7.toUInt()) : CRC<UInt> {
+    override val lookupTable: List<UInt> = (0 until 256).map { crc32(it.toUByte(), polynomial) }
+
+    override var value: UInt = 0.toUInt()
+        private set
+
+    override fun update(inputs: UByteArray) {
+        value = crc32(inputs, value)
+    }
+
+    override fun reset() {
+        value = 0.toUInt()
+    }
+
+    private fun crc32(inputs: UByteArray, initialValue: UInt = 0.toUInt()): UInt {
+        return inputs.fold(initialValue) { remainder, byte ->
+            val bigEndianInput = byte.toBigEndianUInt()
+            val index = (bigEndianInput xor remainder) shr 24
+            lookupTable[index.toInt()] xor (remainder shl 8)
+        }
+    }
+
+    private fun crc32(input: UByte, polynomial: UInt): UInt {
+        val bigEndianInput = input.toBigEndianUInt()
+
+        return (0 until 8).fold(bigEndianInput) { result, _ ->
+            val isMostSignificantBitOne = result and 0x80000000.toUInt() != 0.toUInt()
+            val shiftedResult = result shl 1
+
+            when (isMostSignificantBitOne) {
+                true -> shiftedResult xor polynomial
+                false -> shiftedResult
+            }
+        }
+    }
+}

src/commonMain/kotlin/net.sergeych.bintools/CRC8.kt

@@ -0,0 +1,35 @@
+package net.sergeych.bintools
+
+class CRC8(val polynomial: UByte = 0xA7.toUByte()) : CRC<UByte> {
+    override val lookupTable: List<UByte> = (0 until 256).map { crc8(it.toUByte(), polynomial) }
+
+    override var value: UByte = 0.toUByte()
+        private set
+
+    override fun update(inputs: UByteArray) {
+        value = crc8(inputs, value)
+    }
+
+    override fun reset() {
+        value = 0.toUByte()
+    }
+
+    private fun crc8(inputs: UByteArray, initialValue: UByte = 0.toUByte()): UByte {
+        return inputs.fold(initialValue) { remainder, byte ->
+            val index = byte xor remainder
+            lookupTable[index.toInt()]
+        }
+    }
+
+    private fun crc8(input: UByte, polynomial: UByte): UByte {
+        return (0 until 8).fold(input) { result, _ ->
+            val isMostSignificantBitOne = result and 0x80.toUByte() != 0.toUByte()
+            val shiftedResult = result shl 1
+
+            when (isMostSignificantBitOne) {
+                true -> shiftedResult xor polynomial
+                false -> shiftedResult
+            }
+        }
+    }
+}

src/commonMain/kotlin/net.sergeych.bintools/DataSink.kt

@@ -35,6 +35,9 @@ inline fun <reified T:Any>DataSink.writeNumber(value: T) {
 fun DataSink.writeI32(value: Int) {
     writeBytes(intToBytes(value))
 }
+fun DataSink.writeU32(value: UInt) {
+    writeBytes(uintToBytes(value))
+}
 
 fun DataSink.writeI64(value: Long) {
     writeBytes(longToBytes(value))

src/commonMain/kotlin/net.sergeych.bintools/DataSource.kt

@@ -24,6 +24,7 @@ interface DataSource {
                 a[i] = readByte()
         }
 
+    fun readU32(): UInt = bytesToUInt(readBytes(4))
     fun readI32(): Int = bytesToInt(readBytes(4))
     fun readI64(): Long = bytesToLong(readBytes(8))
 

src/commonMain/kotlin/net.sergeych.bintools/simple_codecs.kt

@@ -21,6 +21,16 @@ fun intToBytes(value: Int): ByteArray {
     return result
 }
 
+fun uintToBytes(value: UInt): ByteArray {
+    var l = value
+    val result = ByteArray(4)
+    for (i in 3 downTo 0) {
+        result[i] = (l and 0xFFu).toByte()
+        l = l shr 8
+    }
+    return result
+}
+
 /**
  * Convert 8 bytes to LE long
  */
@@ -42,6 +52,15 @@ fun bytesToInt(b: ByteArray): Int {
     return result
 }
 
+fun bytesToUInt(b: ByteArray): UInt {
+    var result = 0u
+    for (i in 0 until 4) {
+        result = result shl 8
+        result = result or (b[i].toUInt() and 0xFFu)
+    }
+    return result
+}
+
 
 private val hexDigits = "0123456789ABCDEF"
 

src/commonMain/kotlin/net.sergeych.bipack/BipackDecoder.kt

@@ -8,6 +8,7 @@ import kotlinx.serialization.encoding.CompositeDecoder
 import kotlinx.serialization.modules.EmptySerializersModule
 import kotlinx.serialization.modules.SerializersModule
 import kotlinx.serialization.serializer
+import net.sergeych.bintools.CRC
 import net.sergeych.bintools.DataSource
 import net.sergeych.bintools.readNumber
 import net.sergeych.bintools.toDataSource
@@ -39,12 +40,18 @@ class BipackDecoder(val input: DataSource, var elementsCount: Int = 0) : Abstrac
     }
 
     override fun beginStructure(descriptor: SerialDescriptor): CompositeDecoder {
-        return BipackDecoder(
+        var count = descriptor.elementsCount
-            input,
+        for( a in descriptor.annotations ) {
-            if (descriptor.annotations.any { it is ExtendableFormat })
+            if( a is ExtendableFormat )
-                input.readNumber<UInt>().toInt()
+                count = input.readNumber<UInt>().toInt()
-            else descriptor.elementsCount
+            else if( a is Framed ) {
-        )
+                val code = CRC.crc32(descriptor.serialName.encodeToByteArray())
+                val actual = input.readU32()
+                if( code != actual )
+                    throw InvalidFrameException()
+            }
+        }
+        return BipackDecoder(input, count)
     }
 
     override fun decodeCollectionSize(descriptor: SerialDescriptor): Int =

src/commonMain/kotlin/net.sergeych.bipack/BipackEncoder.kt

@@ -7,10 +7,7 @@ import kotlinx.serialization.encoding.CompositeEncoder
 import kotlinx.serialization.modules.EmptySerializersModule
 import kotlinx.serialization.modules.SerializersModule
 import kotlinx.serialization.serializer
-import net.sergeych.bintools.ArrayDataSink
+import net.sergeych.bintools.*
-import net.sergeych.bintools.DataSink
-import net.sergeych.bintools.writeI64
-import net.sergeych.bintools.writeNumber
 
 class BipackEncoder(val output: DataSink) : AbstractEncoder() {
     override val serializersModule: SerializersModule = EmptySerializersModule
@@ -42,8 +39,16 @@ class BipackEncoder(val output: DataSink) : AbstractEncoder() {
     }
 
     override fun beginStructure(descriptor: SerialDescriptor): CompositeEncoder {
-        if( descriptor.annotations.any { it is ExtendableFormat } )
+        for( a in descriptor.annotations) {
+            if (a is Framed) {
+                output.writeU32(
+                    CRC.crc32(descriptor.serialName.encodeToByteArray())
+                )
+            }
+            else if( a is ExtendableFormat) {
                 encodeUInt(descriptor.elementsCount.toUInt())
+            }
+        }
         return super.beginStructure(descriptor)
     }
 

src/commonMain/kotlin/net.sergeych.bipack/Framed.kt

@@ -0,0 +1,14 @@
+package net.sergeych.bipack
+
+import kotlinx.serialization.SerialInfo
+
+/**
+ * Serializable classes annotated as Framed will have leading checked mark as CRC32
+ * of its name (uses `@SerialName` internally). On deserializing, if frame will not
+ * match the expected name, the [InvalidFrameException] will be thrown.
+ */
+@SerialInfo
+@Target(AnnotationTarget.CLASS)
+annotation class Framed
+
+class InvalidFrameException : Exception("invalid CRC32 serialization frame value")

src/jvmTest/kotlin/net/sergeych/bipack/BipackEncoderTest.kt

@@ -1,17 +1,37 @@
 package net.sergeych.bipack
 
+import kotlinx.serialization.SerialName
 import kotlinx.serialization.Serializable
 import net.sergeych.bintools.toDump
 import org.junit.jupiter.api.Assertions.assertEquals
+import org.junit.jupiter.api.Assertions.assertThrows
 import org.junit.jupiter.api.Test
 
+@Serializable
+data class Foobar1N(val bar: Int, val foo: Int = 117)
+
 @Serializable
 @ExtendableFormat
 data class Foobar1(val bar: Int, val foo: Int = 117)
 
 @Serializable
 @ExtendableFormat
+@SerialName("net.sergeych.bipack.Foobar1")
 data class Foobar2(val bar: Int, val foo: Int,val other: Int = -1)
+@Serializable
+@Framed
+@ExtendableFormat
+data class FoobarF1(val bar: Int, val foo: Int = 117)
+
+@Serializable
+@Framed
+@ExtendableFormat
+@SerialName("net.sergeych.bipack.FoobarF1")
+data class FoobarF2(val bar: Int, val foo: Int,val other: Int = -1)
+@Serializable
+@Framed
+@ExtendableFormat
+data class FoobarF3(val bar: Int, val foo: Int,val other: Int = -1)
 
 class BipackEncoderTest {
 
@@ -23,8 +43,27 @@ class BipackEncoderTest {
         assertEquals(a, b)
         val c = BipackDecoder.decode<Foobar2>(BipackEncoder.encode(a))
         assertEquals(-1, c.other)
-//        assertEquals(a.foo, c.foo)
         assertEquals(a.bar, c.bar)
-//        assertEquals(a.buzz, c.buzz)
+    }
+    @Test
+    fun encodeFramed() {
+        val a = FoobarF1(42)//, "bum")
+        println(BipackEncoder.encode(a).toDump())
+        val b = BipackDecoder.decode<FoobarF1>(BipackEncoder.encode(a))
+        assertEquals(a, b)
+        val c = BipackDecoder.decode<FoobarF2>(BipackEncoder.encode(a))
+        assertEquals(-1, c.other)
+        assertEquals(a.bar, c.bar)
+        assertThrows(InvalidFrameException::class.java) {
+            BipackDecoder.decode<FoobarF3>(BipackEncoder.encode(a))
+        }
+    }
+
+    @Test
+    fun encodeNonExtendable() {
+        val a = Foobar1N(42)//, "bum")
+        println(BipackEncoder.encode(a).toDump())
+        val b = BipackDecoder.decode<Foobar1N>(BipackEncoder.encode(a))
+        assertEquals(a, b)
     }
 }