var x = 0x12345678; var y; Math.imula = function(opA, opB) { opB |= 0; // ensure that opB is an integer. opA will automatically be coerced. // floating points give us 53 bits of precision to work with plus 1 sign bit // automatically handled for our convienence: // 1. 0x003fffff /*opA & 0x000fffff*/ * 0x7fffffff /*opB*/ = 0x1fffff7fc00001 // 0x1fffff7fc00001 < Number.MAX_SAFE_INTEGER /*0x1fffffffffffff*/ var result = (opA & 0x003fffff) * opB; // 2. We can remove an integer coersion from the statement above because: // 0x1fffff7fc00001 + 0xffc00000 = 0x1fffffff800001 // 0x1fffffff800001 < Number.MAX_SAFE_INTEGER /*0x1fffffffffffff*/ if (opA & 0xffc00000 /*!== 0*/) result += (opA & 0xffc00000) * opB |0; return result |0; }; Math.imulb = function(a, b) { var aHi = (a >>> 16) & 0xffff; var aLo = a & 0xffff; var bHi = (b >>> 16) & 0xffff; var bLo = b & 0xffff; // the shift by 0 fixes the sign on the high part // the final |0 converts the unsigned value into a signed value return ((aLo * bLo) + (((aHi * bLo + aLo * bHi) << 16) >>> 0) | 0); };