From d969993997f914afd6b84dc431edac7d2e86d25a Mon Sep 17 00:00:00 2001
From: sergeych <real.sergeych@gmail.com>
Date: Fri, 11 Jul 2025 06:09:09 +0300
Subject: [PATCH] ref #35 bitwise pack/unpack for integers

---
 .../kotlin/net/sergeych/lynon/BitInput.kt     | 10 ++++++++++
 .../kotlin/net/sergeych/lynon/BitOutput.kt    |  2 +-
 lynglib/src/jvmTest/kotlin/LynonTests.kt      | 19 ++++++++++++++++---
 3 files changed, 27 insertions(+), 4 deletions(-)

diff --git a/lynglib/src/commonMain/kotlin/net/sergeych/lynon/BitInput.kt b/lynglib/src/commonMain/kotlin/net/sergeych/lynon/BitInput.kt
index 16e5fc3..f2f2ada 100644
--- a/lynglib/src/commonMain/kotlin/net/sergeych/lynon/BitInput.kt
+++ b/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
+    }
 }
 
diff --git a/lynglib/src/commonMain/kotlin/net/sergeych/lynon/BitOutput.kt b/lynglib/src/commonMain/kotlin/net/sergeych/lynon/BitOutput.kt
index 4b94520..abed9b7 100644
--- a/lynglib/src/commonMain/kotlin/net/sergeych/lynon/BitOutput.kt
+++ b/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())
diff --git a/lynglib/src/jvmTest/kotlin/LynonTests.kt b/lynglib/src/jvmTest/kotlin/LynonTests.kt
index 685153d..f8be460 100644
--- a/lynglib/src/jvmTest/kotlin/LynonTests.kt
+++ b/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())
     }
 
 }
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