0100nnnn01000011
md ← ZeroExtend1(MD);
IF (md = 0)
THROW RESINST;
spc ← SignExtend32(SPC);
op1 ← SignExtend32(Rn);
address ← ZeroExtend32(op1 - 4);
WriteMemory32(address, spc);
op1 ← address;
Rn ← Register(op1);