Portable not-so-smart Heap

Author: dcodeIO

portable-assembly.d.ts

@@ -41,6 +41,10 @@ declare function select<T>(ifTrue: T, ifFalse: T, condition: bool): T;
 declare function sqrt<T = f32 | f64>(value: T): T;
 /** Rounds to the nearest integer towards zero of a 32-bit or 64-bit float. */
 declare function trunc<T = f32 | f64>(value: T): T;
+/** Loads a value of the specified type from memory. Type must be `u8`. */
+declare function load<T = u8>(offset: usize): T;
+/** Stores a value of the specified type to memory. Type must be `u8`. */
+declare function store<T = u8>(offset: usize, value: T): void;
 /** Emits an unreachable operation that results in a runtime error when executed. */
 declare function unreachable(): any; // sic
 

src/glue/js.js

@@ -1,4 +1,4 @@
-require("../../portable-assembly"); // not inherited from tsconfig by ts-node otherwise :(
+require("../../portable-assembly");
 
 // Copy Binaryen exports to global scope
 var globalScope = typeof window !== "undefined" && window || typeof global !== "undefined" && global || self;
@@ -13,9 +13,17 @@ for (var key in binaryen)
     globalScope[key] = binaryen[key];
 
 // Use Binaryen's heap
-Object.defineProperties(globalScope['Heap'] = {
-  allocate: binaryen._malloc,
-  dispose: binaryen._free
+Object.defineProperties(globalScope["Heap"] = {
+  allocate: function allocate(size) {
+    if (!size) return 0; // should be safe in our case
+    return binaryen._malloc(size);
+  },
+  dispose: function dispose(ptr) {
+    if (ptr) binaryen._free(ptr);
+  },
+  copy: function copy(dest, src, n) {
+    return binaryen._memcpy(dest, src, n);
+  }
 }, {
   free: { get: function() { return binaryen.HEAPU8.length; } },
   used: { get: function() { return 0; } },
@@ -24,7 +32,7 @@ Object.defineProperties(globalScope['Heap'] = {
 globalScope["store"] = function store(ptr, val) {
   binaryen.HEAPU8[ptr] = val;
 };
-globalScope["load"] = function load_u8(ptr) {
+globalScope["load"] = function load(ptr) {
   return binaryen.HEAPU8[ptr];
 };
 

std/assembly/heap.ts

@@ -9,9 +9,13 @@ let HEAP_OFFSET: usize = HEAP_START; // HEAP_START is a constant generated by th
 class Heap {
 
   static allocate(size: usize): usize {
+    if (!size) return 0;
+    const len: i32 = current_memory();
+    if (HEAP_OFFSET + size > <usize>len << 16)
+      if(grow_memory(max<i32>(<i32>ceil<f64>(<f64>size / 65536), len * 2 - len)) < 0)
+        unreachable();
     const ptr: usize = HEAP_OFFSET;
-    assert(ptr + size <= (<usize>current_memory() << 16));
-    if (((HEAP_OFFSET += size) & ALIGN_MASK) != 0) // align next offset
+    if ((HEAP_OFFSET += size) & ALIGN_MASK) // align next offset
       HEAP_OFFSET = (HEAP_OFFSET | ALIGN_MASK) + 1;
     return ptr;
   }

std/portable/heap.js

@@ -1,9 +1,34 @@
 var globalScope = typeof window !== "undefined" && window || typeof global !== "undefined" && global || self;
 
-globalScope["Heap"] = {
-  allocate: function() { throw new Error("not implemented"); },
-  dispose: function() { throw new Error("not implemented"); },
-  used: 0,
-  free: 0,
-  size: 0
+var HEAP = new Uint8Array(65536);
+var HEAP_OFFSET = 0;
+
+Object.defineProperties(globalScope["Heap"] = {
+  allocate: function allocate(size) {
+    if (!size) return 0;
+    if (HEAP_OFFSET + size > HEAP.length) {
+      var oldHeap = HEAP;
+      HEAP = new Uint8Array(Math.max(HEAP.length + size, HEAP.length * 2));
+      HEAP.set(oldHeap);
+    }
+    var ptr = HEAP_OFFSET;
+    if ((HEAP_OFFSET += size) & 7)
+      HEAP_OFFSET = (HEAP_OFFSET | 7) + 1;
+    return ptr;
+  },
+  dispose: function dispose() { },
+  copy: function copy(dest, src, n) {
+    HEAP.set(HEAP.subarray(src, src + n), dest);
+    return dest;
+  }
+}, {
+  used: { get: function get_used() { return HEAP_OFFSET; } },
+  free: { get: function get_free() { return HEAP.length - HEAP_OFFSET; } },
+  size: { get: function get_size() { return HEAP.length; } }
+});
+globalScope["store"] = function store(ptr, val) {
+  binaryen.HEAPU8[ptr] = val;
+};
+globalScope["load"] = function load(ptr) {
+  return binaryen.HEAPU8[ptr];
 };