func findNops(e *dcpu16.Emulator, st *emu.State, pc uint16, in []uint16) (out []uint16) {
diff := new(emu.Diff)
for _, op := range in {
var code emu.Code
st.Mem[2*int(pc)] = byte(op & 0xFF)
st.Mem[2*int(pc)+1] = byte((op >> 8) & 0xFF)
st.Mem[2*int(pc+1)] = st.Mem[2*int(pc)]
st.Mem[2*int(pc+1)+1] = st.Mem[2*int(pc)+1]
st.Reg[dcpu16.PC] = uint64(pc)
diff.Clear()
code = e.Step(st, diff)
// fmt.Printf("%+v\n", diff)
if code != emu.OK || len(diff.Mem) != 0 || len(diff.Reg) != 1 || !diff.Reg.Has(dcpu16.PC, uint64(pc+1)) {
continue
}
st.Apply(diff)
diff.Clear()
code = e.Step(st, diff)
// fmt.Printf("%+v\n", diff)
if code != emu.OK || len(diff.Mem) != 0 || len(diff.Reg) != 1 || !diff.Reg.Has(dcpu16.PC, uint64(pc+2)) {
continue
}
out = append(out, op)
}
return
}
func (st *state) Step(diff *emu.Diff) (code emu.Code) {
if code = st.doStep(); code != emu.OK {
return
}
diff.Mem = st.mem.Diff(diff.Mem)
diff.Reg = st.reg.Diff(diff.Reg)
return
}