def write_push_virtual(segment, location):
primitive_ml.write_const_to(location, 'D')
primitive_ml.point_to_segment(segment)
primitive_ml.write_c_command('D', 'M+D')
primitive_ml.point_to_segment(segment, True)
primitive_ml.write_c_command('A', 'D')
primitive_ml.write_c_command('D', 'M')
primitive_ml.write_to_stack('D')
def write_push_command(line_def):
if line_def['command_type'] != vm_command_type.Push:
return
segment = line_def['arg'][0]
location = line_def['arg'][1]
if segment == 'constant':
add_line('@' + location)
add_line('D=A')
primitive_ml.write_to_stack('D')
elif segment == 'temp':
write_push_temp(location)
elif segment == 'pointer':
write_push_pointer(location)
elif segment == 'static':
write_push_static(location)
else:
write_push_virtual(segment, location)
def write_call(name, var_count):
# push return-address (using label below)
global return_counter
return_label = 'return.' + str(return_counter)
primitive_ml.add_line('@' + return_label)
primitive_ml.write_c_command('D', 'A')
primitive_ml.write_to_stack('D')
# push lcl
read_symbol_to_stack('LCL')
read_symbol_to_stack('ARG')
read_symbol_to_stack('THIS')
read_symbol_to_stack('THAT')
# reposition arg
primitive_ml.add_line('@SP')
primitive_ml.write_c_command('D', 'M')
primitive_ml.add_line('@ARG')
primitive_ml.write_c_command('M', 'D')
primitive_ml.add_line('@5')
primitive_ml.write_c_command('D', 'A')
primitive_ml.add_line('@ARG')
primitive_ml.write_c_command('M', 'M-D')
primitive_ml.add_line('@' + str(var_count))
primitive_ml.write_c_command('D', 'A')
primitive_ml.add_line('@ARG')
primitive_ml.write_c_command('M', 'M-D')
# reposition lcl
primitive_ml.add_line('@SP')
primitive_ml.write_c_command('D', 'M')
primitive_ml.add_line('@LCL')
primitive_ml.write_c_command('M', 'D')
# goto function
primitive_ml.unconditional_jump(name)
# declare return label
primitive_ml.add_symbol_link(return_label)
return_counter += 1
return
def write_push_static(location):
global file_name
primitive_ml.point_static(file_name, location)
primitive_ml.write_c_command('D', 'M')
primitive_ml.write_to_stack('D')
def write_push_pointer(location):
primitive_ml.point_to_pointer(int(location))
primitive_ml.write_c_command('D', 'M')
primitive_ml.write_to_stack('D')
def read_symbol_to_stack(symbol):
primitive_ml.add_line('@' + symbol)
primitive_ml.write_c_command('D', 'M')
primitive_ml.write_to_stack('D')
def write_function(name, var_count):
primitive_ml.add_symbol_link(name)
while var_count > 0:
primitive_ml.write_to_stack('0')
var_count -= 1
return