fix memory alignment check (#1742)

* fix memory alignment check

* added test for memory alignment

ktor-io/posix/src/io/ktor/utils/io/bits/PrimitiveArraysNative.kt

@@ -533,9 +533,9 @@ internal inline fun requireRange(offset: Long, length: Long, size: Long, name: S
     }
 }
 
-private inline fun Memory.isAlignedShort(offset: Long) = (pointer.toLong() + offset) and 1L == 0L
-private inline fun Memory.isAlignedInt(offset: Long) = (pointer.toLong() + offset) and 11L == 0L
-private inline fun Memory.isAlignedLong(offset: Long) = (pointer.toLong() + offset) and 111L == 0L
+internal inline fun Memory.isAlignedShort(offset: Long) = (pointer.toLong() + offset) and 0b1 == 0L
+internal inline fun Memory.isAlignedInt(offset: Long) = (pointer.toLong() + offset) and 0b11 == 0L
+internal inline fun Memory.isAlignedLong(offset: Long) = (pointer.toLong() + offset) and 0b111 == 0L
 
 
 private fun copy(

ktor-io/posix/test/io/ktor/utils/io/tests/MemoryTest.kt

@@ -0,0 +1,70 @@
+/*
+ * Copyright 2014-2020 JetBrains s.r.o and contributors. Use of this source code is governed by the Apache 2.0 license.
+ */
+
+package io.ktor.utils.io.tests
+
+import io.ktor.utils.io.bits.*
+import kotlinx.cinterop.*
+import kotlin.test.*
+
+class MemoryTest {
+
+    private lateinit var mem: Memory
+
+    @BeforeTest
+    fun setup() {
+        mem = DefaultAllocator.alloc(1024)
+    }
+
+    @AfterTest
+    fun cleanup() {
+        DefaultAllocator.free(mem)
+    }
+
+    @Test
+    fun testShortAlign() {
+        assertTrue(mem.isAlignedShort(0))
+        assertFalse(mem.isAlignedShort(1))
+
+        assertTrue(mem.isAlignedShort(510))
+        assertFalse(mem.isAlignedShort(511))
+        assertTrue(mem.isAlignedShort(512))
+    }
+
+    @Test
+    fun testIntAlign() {
+        assertTrue(mem.isAlignedInt(0))
+        assertFalse(mem.isAlignedInt(1))
+        assertFalse(mem.isAlignedInt(2))
+        assertFalse(mem.isAlignedInt(3))
+
+        assertTrue(mem.isAlignedInt(508))
+        assertFalse(mem.isAlignedInt(509))
+        assertFalse(mem.isAlignedInt(510))
+        assertFalse(mem.isAlignedInt(511))
+        assertTrue(mem.isAlignedInt(512))
+    }
+
+    @Test
+    fun testLongAlign() {
+        assertTrue(mem.isAlignedLong(0))
+        assertFalse(mem.isAlignedLong(1))
+        assertFalse(mem.isAlignedLong(2))
+        assertFalse(mem.isAlignedLong(3))
+        assertFalse(mem.isAlignedLong(4))
+        assertFalse(mem.isAlignedLong(6))
+        assertFalse(mem.isAlignedLong(6))
+        assertFalse(mem.isAlignedLong(7))
+
+        assertTrue(mem.isAlignedLong(504))
+        assertFalse(mem.isAlignedLong(505))
+        assertFalse(mem.isAlignedLong(506))
+        assertFalse(mem.isAlignedLong(507))
+        assertFalse(mem.isAlignedLong(508))
+        assertFalse(mem.isAlignedLong(509))
+        assertFalse(mem.isAlignedLong(510))
+        assertFalse(mem.isAlignedLong(511))
+        assertTrue(mem.isAlignedLong(512))
+    }
+}