code: function rlist_lr(value) {
     var regs = value.split(",");
     var vals = { r0:1,r1:2,r2:4,r3:8,r4:16,r5:32,r6:64,r7:128,lr:256 };
     var bits = 0;
     for (var i in regs) {
       var reg = regs[i].trim();
       if (!(reg in vals))  throw "Unknown register name "+reg;
       bits |= vals[reg];
     }
     return bits;
    }
docs: /*  Thumb reference :
  http://ece.uwaterloo.ca/~ece222/ARM/ARM7-TDMI-manual-pt3.pdf
  
  ARM reference
  https://web.eecs.umich.edu/~prabal/teaching/eecs373-f11/readings/ARMv7-M_ARM.pdf
   list of registers (for push/pop type commands)