Make TLSF always align to 8 bytes, see #15

std/assembly/allocator/arena.ts

@@ -1,8 +1,9 @@
-/////////////// A simple yet effective Arena Memory Allocator /////////////////
-
-// Provides a `reset_memory` function to reset the heap to its initial state. A
-// user has to make sure that there are no more references to cleared memory
-// afterwards. Always aligns to 8 bytes.
+/**
+ * @file Arena Memory Allocator
+ *
+ * Provides a `reset_memory` function to reset the heap to its initial state. A user has to make
+ * sure that there are no more references to cleared memory afterwards. Always aligns to 8 bytes.
+ */
 
 const ALIGN_LOG2: usize = 3;
 const ALIGN_SIZE: usize = 1 << ALIGN_LOG2;

std/assembly/allocator/emscripten.ts

@@ -1,8 +1,10 @@
-///////////////////////// Emscripten Memory Allocator //////////////////////////
-
-// Uses Emscripten's exported _malloc and _free implementations, i.e., when
-// linking with Emscripten-compiled programs that already provide these.
-// Differs from 'system' in that their names are prefixed with an underscore.
+/**
+ * @file Emscripten Memory Allocator
+ *
+ * Uses Emscripten's exported _malloc and _free implementations, i.e., when linking with
+ * Emscripten-compiled programs that already provide these. Differs from 'system' in that their
+ * names are prefixed with an underscore.
+ */
 
 declare function _malloc(size: usize): usize;
 declare function _free(ptr: usize): void;

std/assembly/allocator/none.ts

@@ -1,3 +1,7 @@
+/**
+ * @file Memory Allocator Stub
+ */
+
 export function allocate_memory(size: usize): usize {
   throw new Error("not supported");
 }

std/assembly/allocator/system.ts

@@ -1,7 +1,9 @@
-/////////////////////////// System Memory Allocator ////////////////////////////
-
-// Uses the environment's malloc and free implementations, i.e., when linking
-// with other C-like programs that already provide these.
+/**
+ * @file System Memory Allocator
+ *
+ * Uses the environment's malloc and free implementations, i.e., when linking with other C-like
+ * programs that already provide these.
+ */
 
 declare function malloc(size: usize): usize;
 declare function free(ptr: usize): void;

std/assembly/allocator/tlsf.ts

@@ -1,4 +1,9 @@
-////////////// TLSF (Two-Level Segregate Fit) Memory Allocator ////////////////
+/**
+ * @file Two-Level Segregate Fit Memory Allocator
+ *
+ * A general purpose dynamic memory allocator specifically designed to meet real-time requirements.
+ * Always aligns to 8 bytes.
+ */
 
 // ╒══════════════ Block size interpretation (32-bit) ═════════════╕
 //    3                   2                   1
@@ -8,7 +13,7 @@
 // └───────────────────────────────────────────────┴─────────╨─────┘
 // FL: first level, SL: second level, AL: alignment, SB: small block
 
-const AL_BITS: u32 = sizeof<usize>() == sizeof<u32>() ? 2 : 3;
+const AL_BITS: u32 = 3; // always align to 8 bytes
 const AL_SIZE: usize = 1 << <usize>AL_BITS;
 const AL_MASK: usize = AL_SIZE - 1;
 
@@ -46,8 +51,6 @@ const LEFT_FREE: usize = 1 << 1;
 /** Mask to obtain all tags. */
 const TAGS: usize = FREE | LEFT_FREE;
 
-assert(AL_BITS >= 2); // alignment must be large enough to store all tags
-
 /** Block structure. */
 @unmanaged
 class Block {
@@ -56,7 +59,7 @@ class Block {
   info: usize;
 
   /** End offset of the {@link Block#info} field. User data starts here. */
-  static readonly INFO: usize = sizeof<usize>();
+  static readonly INFO: usize = (sizeof<usize>() + AL_MASK) & ~AL_MASK;
 
   /** Previous free block, if any. Only valid if free. */
   prev: Block | null;
@@ -64,7 +67,7 @@ class Block {
   next: Block | null;
 
   /** Minimum size of a block, excluding {@link Block#info}. */
-  static readonly MIN_SIZE: usize = 3 * sizeof<usize>(); // prev + next + jump
+  static readonly MIN_SIZE: usize = (3 * sizeof<usize>() + AL_MASK) & ~AL_MASK;// prev + next + jump
 
   /** Maximum size of a used block, excluding {@link Block#info}. */
   static readonly MAX_SIZE: usize = 1 << (FL_BITS + SB_BITS);
@@ -445,7 +448,7 @@ export function allocate_memory(size: usize): usize {
         root.setHead(fl, sl, null);
       }
     }
-    root.addMemory(rootOffset + Root.SIZE, current_memory() << 16);
+    root.addMemory((rootOffset + Root.SIZE + AL_MASK) & ~AL_MASK, current_memory() << 16);
   }
 
   // search for a suitable block

tests/allocators/buddy/assembly/buddy.ts

@@ -1,3 +1,7 @@
+/**
+ * @file Buddy Memory Allocator
+ */
+
 /*
   Copyright 2018 Evan Wallace
 

tests/allocators/runner.js

@@ -7,7 +7,8 @@ function runner(allocator, runs, allocs) {
     size = (size + 3) & ~3;
     var ptr = allocator.allocate_memory(size);
     if (!ptr) throw Error();
-    if (ptrs.indexOf(ptr) >= 0) throw Error();
+    if ((ptr & 7) != 0) throw Error("invalid alignment: " + (ptr & 7) + " on " + ptr);
+    if (ptrs.indexOf(ptr) >= 0) throw Error("duplicate pointer");
     if (allocator.set_memory)
       allocator.set_memory(ptr, 0xdc, size);
     ptrs.push(ptr);