A Mozilla Research project to specify and develop the extremely optimizable subset of JS targeted by compilers like Emscripten, Mandreel, and LLJS.
Discussion of the asm.js spec now takes place on Specifiction here.
The spec repo hosts the source for the current asm.js Working Draft.
This repo hosts JS source code which performs asm.js validation, however as of this update, this code is not up to date with the latest working draft and is not extensively tested. Patches to update it or fix bugs are welcome though.
function mymodule(stdlib, foreign, heap) {
"use asm";
// -------------------------------------------------------------------------
// SECTION 1: globals
var H32 = new stdlib.Int32Array(heap);
var HU32 = new stdlib.Uint32Array(heap);
var log = foreign.consoleDotLog;
var g_i = 0; // int global
var g_f = 0.0; // double global
// -------------------------------------------------------------------------
// SECTION 2: functions
function f(x, y) {
// SECTION A: parameter type declarations
x = x|0; // int parameter
y = +y; // double parameter
// SECTION B: function body
log(x|0); // call into FFI -- must force the sign
log(y); // call into FFI -- already know it's a double
x = (x+3)|0; // signed addition
// SECTION C: unconditional return
return ((((x+1)|0)>>>0)/(x>>>0))|0; // compound expression
}
function g() {
g_f = +(g_i|0); // read/write globals
return;
}
function g2() {
return;
}
function h(i, x) {
i = i|0;
x = x|0;
H32[i>>2] = x; // shifted by log2(byte count)
ftable_2[(x-2)&1](); // dynamic call of functions in table 2
// no return necessary when return type is void
}
// -------------------------------------------------------------------------
// SECTION 3: function tables
var ftable_1 = [f];
var ftable_2 = [g, g2]; // all of the same type
// -------------------------------------------------------------------------
// SECTION 4: exports
return { f_export: f, goop: g };
}