"""
The DECR operation.
Subtracts one from the given argument (in place).
"""
from itertools import product
from ..language_defs import (
INSTRUCTION_GROUPS,
MODULE_CONTROL,
ALU_CONTROL_FLAGS,
ALU_OPERATIONS,
ALU_OPERANDS,
FLAGS,
instruction_byte_from_bitdefs,
)
from ..operation_utils import assemble_instruction, match_and_parse_line
from ..data_structures import (
get_arg_def_template, get_machine_code_byte_template
)
_NAME = "DECR"
[docs]def generate_signatures():
"""
Generate the definitions of all possible arguments passable.
Returns:
list(list(dict)): All possible arguments. See
:func:`~.get_arg_def_template` for more information.
"""
signatures = []
for register in ("ACC", "A", "B", "C"):
signature = []
arg_def = get_arg_def_template()
arg_def["value_type"] = "module_name"
arg_def["value"] = register
signature.append(arg_def)
signatures.append(signature)
return signatures
[docs]def generate_microcode_templates():
"""
Generate microcode for all the DECR operations.
Returns:
list(DataTemplate): DataTemplates for all the DECR microcode.
"""
data_templates = []
signatures = generate_signatures()
for signature in signatures:
templates = generate_operation_templates(signature)
data_templates.extend(templates)
return data_templates
[docs]def generate_operation_templates(signature):
"""
Create the DataTemplates to define an DECR with the given args.
Args:
signature (list(dict)): List of argument definitions that
specify which particular not operation to generate
templates for.
Returns:
list(DataTemplate) : Datatemplates that define this not.
"""
instruction_byte_bitdefs = generate_instruction_byte_bitdefs(signature)
flags_bitdefs = [FLAGS["ANY"]]
step_0 = [
MODULE_CONTROL[signature[0]["value"]]["OUT"],
MODULE_CONTROL["ALU"]["A_IS_BUS"],
MODULE_CONTROL["ALU"]["STORE_RESULT"],
MODULE_CONTROL["ALU"]["STORE_FLAGS"],
]
step_0.extend(ALU_CONTROL_FLAGS["A_MINUS_1"])
step_1 = [
MODULE_CONTROL["ALU"]["OUT"],
MODULE_CONTROL[signature[0]["value"]]["IN"],
]
control_steps = [step_0, step_1]
return assemble_instruction(
instruction_byte_bitdefs, flags_bitdefs, control_steps
)
[docs]def generate_instruction_byte_bitdefs(signature):
"""
Generate bitdefs to specify the instruction byte for these args.
Args:
signature (list(dict)): List of argument definitions that
specify which particular not operation to generate
the instruction byte bitdefs for.
Returns:
list(str): Bitdefs that make up the instruction_byte
"""
if signature[0]["value"] == "ACC":
alu_operands = ALU_OPERANDS["ACC/CONST"]
else:
alu_operands = ALU_OPERANDS[signature[0]["value"]]
return [
INSTRUCTION_GROUPS["ALU"],
ALU_OPERATIONS["DECR"],
alu_operands,
]
[docs]def parse_line(line):
"""
Parse a line of assembly code to create machine code byte templates.
If a line is not identifiably an DECR assembly line, return an
empty list instead.
Args:
line (str): Assembly line to be parsed.
Returns:
list(dict): List of instruction byte template dictionaries or an
empty list.
"""
match, signature = match_and_parse_line(
line, _NAME, generate_signatures()
)
if not match:
return []
instruction_byte = instruction_byte_from_bitdefs(
generate_instruction_byte_bitdefs(signature)
)
mc_byte = get_machine_code_byte_template()
mc_byte["byte_type"] = "instruction"
mc_byte["bitstring"] = instruction_byte
return [mc_byte]