def run(state: programState.ProgramState) -> Tuple[programState.ProgramState, Union[programState.RunError, None]]:
a, err = state.getReg(arg2)
if isinstance(arg3, str):
if err is None:
b, err = state.getReg(arg3)
else:
b, _ = state.getReg(arg3)
if b > 32:
return state, programState.RunError(f"Shift value is out of range: value must be below 33 but is {b}", programState.RunError.ErrorType.Error)
else:
b = arg3
out = a >> b
out32 = out & 0xFFFF_FFFF
if ((a >> 31) & 1) == 1: # sign-extend
out32 |= (0xFFFF_FFFF << (32 - b)) & 0xFFFF_FFFF
if b == 0:
c = state.status.C # The C flag is unaffected if the shift value is 0 - ARM docs
else:
c = bool((a >> (b-1)) & 1) # Get last bit shifted out
n = bool((out32 >> 31) & 1)
z = out32 == 0
state.setReg(arg1, out32)
state.setALUState(programState.StatusRegister(n, z, c, False))
return state, err
def branchToLabel(state: programState.ProgramState, label: str) -> Tuple[programState.ProgramState, Union[programState.RunError, None]]:
# Save return address in LR
state.setReg("LR", state.getReg("PC"))
address: Union[int, programState.RunError] = state.getLabelAddress(label)
if isinstance(address, programState.RunError):
return state, programState.RunError(f"Unknown startup label: {label}", programState.RunError.ErrorType.Error)
else:
# Subtract 4 because we will add 4 to the address later in the run loop and we need to start at address and not address+4
state.setReg("PC", address - 4)
state.hasReturned = False
return state, None
def pop(state: programState.ProgramState) -> Tuple[programState.ProgramState, Union[programState.RunError, None]]:
if len(regs) == 0:
return state, None
# head, *tail = registers
address = state.getReg("SP")
# check address is in 0...stacksize
if address > (state.getLabelAddress("__STACKSIZE")) or address < 0:
return state, programState.RunError("All stack entries have been pop'ed already", programState.RunError.ErrorType.Error)
for reg in regs:
err = state.loadRegister(address, 32, False, reg)
address += 4
if err is not None:
return state, err
state.setReg("SP", address)
return state, None
def push(state: programState.ProgramState) -> Tuple[programState.ProgramState, Union[programState.RunError, None]]:
if len(regs) == 0:
return state, None
# head, *tail = registers
address = state.getReg("SP")
# check address is in 0...stacksize
if address > (state.getLabelAddress("__STACKSIZE")) or address < 0:
return state, programState.RunError("Stack overflow", programState.RunError.ErrorType.Error)
for reg in regs:
address -= 4
err = state.storeRegister(address, reg, 32)
if err is not None:
return state, err
state.setReg("SP", address)
return state, None
def run(state: programState.ProgramState) -> Tuple[programState.ProgramState, Union[programState.RunError, None]]:
a = state.getReg(arg2)
if isinstance(arg3, str):
b = state.getReg(arg3)
if b > 31:
return state, programState.RunError(f"Shift value is out of range: value must be below 32 but is {b}", programState.RunError.ErrorType.Error)
else:
b = arg3
out = a << b
out32 = out & 0xFFFF_FFFF
if b == 0:
c = state.status.C # The C flag is unaffected if the shift value is 0 - ARM docs
else:
c = bool((out >> 32) & 1) # Get the last bit shifted out
n = bool((out32 >> 31) & 1)
z = out32 == 0
state.setReg(arg1, out32)
state.setALUState(programState.StatusRegister(n, z, c, False))
return state, None