ref #35 bitwise pack/unpack for integers

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

@@ -47,6 +47,10 @@ abstract class BitInput {
         return getBitsOrNull(count) ?: throw IllegalStateException("Unexpected end of stream")
     }
 
+    fun getBit(): Int {
+        return getBitOrNull() ?: throw IllegalStateException("Unexpected end of stream")
+    }
+
     fun unpackUnsigned(): ULong {
         val tetrades = getBits(4).toInt()
         var result = 0UL
@@ -57,5 +61,11 @@ abstract class BitInput {
         }
         return result
     }
+
+    fun unpackSigned(): Long {
+        val isNegative = getBit()
+        val value = unpackUnsigned().toLong()
+        return if( isNegative == 1) -value else value
+    }
 }
 

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

@@ -45,7 +45,7 @@ abstract class BitOutput {
     }
 
     @Suppress("unused")
-    fun putSigned(value: Long) {
+    fun packSigned(value: Long) {
         if( value < 0 ) {
             putBit(1)
             packUnsigned((-value).toULong())

lynglib/src/jvmTest/kotlin/LynonTests.kt

@@ -37,13 +37,26 @@ class LynonTests {
     }
 
     @Test
-    fun testPackInteger() {
+    fun testUnsignedPackInteger() {
         val bout = MemoryBitOutput()
-        bout.packUnsigned(147179UL)
+        bout.packUnsigned(1471792UL)
         bout.close()
         println(bout.toUByteArray().toDump())
         val bin = MemoryBitInput(bout.toUByteArray())
-        assertEquals(147179UL, bin.unpackUnsigned())
+        assertEquals(1471792UL, bin.unpackUnsigned())
+    }
+
+    @Test
+    fun testSignedPackInteger() {
+        val bout = MemoryBitOutput()
+        bout.packSigned(-1471792L)
+        bout.packSigned(1471792L)
+//        bout.packSigned(147179L)
+        bout.close()
+        println(bout.toUByteArray().toDump())
+        val bin = MemoryBitInput(bout.toUByteArray())
+        assertEquals(-1471792L, bin.unpackSigned())
+        assertEquals(1471792L, bin.unpackSigned())
     }
 
 }