Reprint the essence of a forgotten source [MD5 encrypted JavaScript implementation Example]

/* MD5 message-digest Algorithm-javascript
' Modification HISTORY:
' 1.0 16-feb-2001-phil Fresle (sales@frez.co.uk)-Initial Version (vb/asp code)
' 1.0 21-feb-2001-enrico Mosanghini (erik504@yahoo.com)-JavaScript porting
*/
function MD5 (smessage) {
function Rotateleft (LValue, ishiftbits) {return (lvalue<<ishiftbits) | (Lvalue>>> (32-ishiftbits)); }
function addunsigned (lx,ly) {
var Lx4,ly4,lx8,ly8,lresult;
LX8 = (LX & 0x80000000);
LY8 = (LY & 0x80000000);
LX4 = (LX & 0x40000000);
LY4 = (LY & 0x40000000);
LRESULT = (LX & 0x3fffffff) + (LY & 0X3FFFFFFF);
if (LX4 & lY4) return (lresult ^ 0x80000000 ^ lX8 ^ lY8);
if (lX4 | lY4) {
if (Lresult & 0x40000000) return (lresult ^ 0xc0000000 ^ lX8 ^ lY8);
else return (lresult ^ 0x40000000 ^ lX8 ^ lY8);
else return (lresult ^ lX8 ^ lY8);
}
function F (x,y,z) {return (x & y) | ((~x) & Z); }
function G (x,y,z) {return (X & Z) | (Y & (~z)); }
function H (x,y,z) {return (x ^ y ^ z);}
function I (x,y,z) {return (y ^ (x | (~z))); }
function FF (A,B,C,D,X,S,AC) {
A = addunsigned (A, addunsigned (addunsigned (F (b, C, D), x), AC);
Return addunsigned (Rotateleft (A, s), b);
}
function GG (A,B,C,D,X,S,AC) {
A = addunsigned (A, addunsigned (addunsigned (G (b, C, D), x), AC);
Return addunsigned (Rotateleft (A, s), b);
}
function HH (A,B,C,D,X,S,AC) {
A = addunsigned (A, addunsigned (addunsigned (H (b, C, D), x), AC);