switch to signed-first approach

It turns out signed math is more performant

src/commonMain/kotlin/com/infendro/bytes/intarray/Copy.kt

@@ -0,0 +1,49 @@
+package com.infendro.bytes.intarray
+
+import com.infendro.bytes.ByteOrder
+import com.infendro.bytes.ByteOrder.BIG_ENDIAN
+import com.infendro.bytes.ByteOrder.LITTLE_ENDIAN
+
+fun IntArray.copyInto(
+    destination: ByteArray,
+    destinationOffset: Int = 0,
+    startIndex: Int = 0,
+    endIndex: Int = size,
+    order: ByteOrder = BIG_ENDIAN,
+) {
+    val length = endIndex - startIndex
+    require(length >= 0)
+    require(startIndex in 0..(size - length))
+    require(destinationOffset in 0..(destination.size - (length * 4)))
+
+    when (order) {
+        BIG_ENDIAN -> {
+            repeat(length) { i ->
+                val offset = destinationOffset + (i * 4)
+                val value = this[startIndex + i]
+                destination[offset] = (value shr 24).toByte()
+                destination[offset + 1] = (value shr 16).toByte()
+                destination[offset + 2] = (value shr 8).toByte()
+                destination[offset + 3] = value.toByte()
+            }
+        }
+        LITTLE_ENDIAN -> {
+            repeat(length) { i ->
+                val offset = destinationOffset + (i * 4)
+                val value = this[startIndex + i]
+                destination[offset] = value.toByte()
+                destination[offset + 1] = (value shr 8).toByte()
+                destination[offset + 2] = (value shr 16).toByte()
+                destination[offset + 3] = (value shr 24).toByte()
+            }
+        }
+    }
+}
+
+fun IntArray.copyInto(
+    destination: UByteArray,
+    destinationOffset: Int = 0,
+    startIndex: Int = 0,
+    endIndex: Int = size,
+    order: ByteOrder = BIG_ENDIAN,
+) = copyInto(destination.asByteArray(), destinationOffset, startIndex, endIndex, order)