Add conditional BigInt support to loader & minor README fixes

Author: dcodeIO

lib/loader/README.md

@@ -48,6 +48,12 @@ Instances are automatically populated with useful utility:
 * **U32**: `Uint32Array`<br />
   A 32-bit unsigned integer view on the memory.
 
+* **I64**: `BigInt64Array`<br />
+  A 64-bit signed integer view on the memory<sup>1</sup>.
+
+* **U64**: `BigUint64Array`<br />
+  A 64-bit unsigned integer view on the memory<sup>1</sup>.
+
 * **F32**: `Float32Array`<br />
   A 32-bit float view on the memory.
 
@@ -65,6 +71,8 @@ Instances are automatically populated with useful utility:
 * **getString**(ptr: `number`): `string`<br />
   Gets a string from the module's memory by its pointer.
 
+<sup>1</sup> This feature has not yet landed in any VM as of this writing.
+
 Examples
 --------
 
@@ -82,13 +90,16 @@ const myModule = await loader.instantiateStreaming(fetch("myModule.wasm"), myImp
 
 ```js
 var ptrToInt8 = ...;
-var value = myModule.U16[ptrToInt8]; // alignment of log2(1)=0
+var value = myModule.I8[ptrToInt8]; // alignment of log2(1)=0
 
 var ptrToInt16 = ...;
-var value = myModule.U16[ptrToInt16 >>> 1]; // alignment of log2(2)=1
+var value = myModule.I16[ptrToInt16 >>> 1]; // alignment of log2(2)=1
 
 var ptrToInt32 = ...;
-var value = myModule.U32[ptrToInt32 >>> 2]; // alignment of log2(4)=2
+var value = myModule.I32[ptrToInt32 >>> 2]; // alignment of log2(4)=2
+
+var ptrToInt64 = ...;
+var value = myModule.I64[ptrToInt64 >>> 3]; // alignment of log2(8)=3
 
 var ptrToFloat32 = ...;
 var value = myModule.F32[ptrToFloat32 >>> 2]; // alignment of log2(4)=2
@@ -97,9 +108,10 @@ var ptrToFloat64 = ...;
 var value = myModule.F64[ptrToFloat64 >>> 3]; // alignment of log2(8)=3
 
 // Likewise, for writing
-myModule.U16[ptrToInt8] = newValue;
-myModule.U16[ptrToInt16 >>> 1] = newValue;
-myModule.U32[ptrToInt32 >>> 2] = newValue;
+myModule.I8[ptrToInt8] = newValue;
+myModule.I16[ptrToInt16 >>> 1] = newValue;
+myModule.I32[ptrToInt32 >>> 2] = newValue;
+myModule.I64[ptrToInt64 >>> 3] = newValue;
 myModule.F32[ptrToFloat32 >>> 2] = newValue;
 myModule.F64[ptrToFloat64 >>> 3] = newValue;
 ```
@@ -128,5 +140,3 @@ import MyModule from "myModule"; // pointing at the d.ts
 
 const myModule = loader.instatiateBuffer<typeof MyModule>(fs.readFileSync("myModule.wasm"), myImports);
 ```
-
-**Hint:** You can produce a `.d.ts` for your module with the `-d` option on the command line.

lib/loader/index.d.ts

@@ -13,21 +13,25 @@ interface ImportsObject {
 /** Utility mixed in by the loader. */
 interface ASUtil {
   /** An 8-bit signed integer view on the memory. */
-  readonly I8: Uint8Array,
+  readonly I8: Uint8Array;
   /** An 8-bit unsigned integer view on the memory. */
-  readonly U8: Uint8Array,
+  readonly U8: Uint8Array;
   /** A 16-bit signed integer view on the memory. */
-  readonly I16: Uint16Array,
+  readonly I16: Uint16Array;
   /** A 16-bit unsigned integer view on the memory. */
-  readonly U16: Uint16Array,
+  readonly U16: Uint16Array;
   /** A 32-bit signed integer view on the memory. */
-  readonly I32: Uint32Array,
+  readonly I32: Uint32Array;
   /** A 32-bit unsigned integer view on the memory. */
-  readonly U32: Uint32Array,
+  readonly U32: Uint32Array;
+  /** A 64-bit signed integer view on the memory. */
+  readonly I64: any; // BigInt64Array
+  /** A 64-bit unsigned integer vieww on the memory. */
+  readonly U64: any; // BigUint64Array
   /** A 32-bit float view on the memory. */
-  readonly F32: Float32Array,
+  readonly F32: Float32Array;
   /** A 64-bit float view on the memory. */
-  readonly F64: Float64Array,
+  readonly F64: Float64Array;
   /** Allocates a new string in the module's memory and returns its pointer. */
   newString(str: string): number;
   /** Gets a string from the module's memory by its pointer. */

lib/loader/index.js

@@ -1,5 +1,7 @@
 "use strict";
 
+const hasBigInt64 = typeof BigUint64Array !== "undefined";
+
 /** Instantiates an AssemblyScript module using the specified imports. */
 function instantiate(module, imports) {
 
@@ -17,7 +19,7 @@ function instantiate(module, imports) {
   var exports = instance.exports;
 
   // Provide views for all sorts of basic values
-  var mem, I8, U8, I16, U16, I32, U32, F32, F64;
+  var mem, I8, U8, I16, U16, I32, U32, F32, F64, I64, U64;
 
   /** Updates memory views if memory has grown meanwhile. */
   function checkMem() {
@@ -30,6 +32,10 @@ function instantiate(module, imports) {
       U16 = new Uint16Array(mem);
       I32 = new Int32Array(mem);
       U32 = new Uint32Array(mem);
+      if (hasBigInt64) {
+        I64 = new BigInt64Array(mem);
+        U64 = new BigUint64Array(mem);
+      }
       F32 = new Float32Array(mem);
       F64 = new Float64Array(mem);
     }
@@ -73,6 +79,8 @@ function instantiate(module, imports) {
     get U16() { checkMem(); return U16; },
     get I32() { checkMem(); return I32; },
     get U32() { checkMem(); return U32; },
+    get I64() { checkMem(); return I64; },
+    get U64() { checkMem(); return U64; },
     get F32() { checkMem(); return F32; },
     get F64() { checkMem(); return F64; },
     newString,