"""
The JUMP_IF_EQ_ZERO operation.
Sets PC (jumps) to a constant if the module passed as an argument is
equal to zero.
This operation will generate and store (clobber) ALU flags.
"""
from ..language_defs import (
INSTRUCTION_GROUPS,
MODULE_CONTROL,
DEST_REGISTERS,
SRC_REGISTERS,
ALU_CONTROL_FLAGS,
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 = "JUMP_IF_EQ_ZERO"
[docs]def generate_microcode_templates():
"""
Generate microcode for all the JUMP_IF_EQ_ZERO operations.
Returns:
list(DataTemplate): DataTemplates for all the JUMP_IF_EQ_ZERO
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_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 = []
# Add module arguments
for dest in ("ACC", "A", "B", "C", "PC", "SP"):
signature = []
arg0_def = get_arg_def_template()
arg0_def["value_type"] = "module_name"
arg0_def["is_memory_location"] = False
arg0_def["value"] = dest
signature.append(arg0_def)
arg1_def = get_arg_def_template()
arg1_def["value_type"] = "constant"
arg1_def["is_memory_location"] = False
signature.append(arg1_def)
signatures.append(signature)
return signatures
[docs]def generate_operation_templates(signature):
"""
Create the DataTemplates to define a JUMP_IF_EQ_ZERO with the given
args.
Args:
signature (list(dict)): List of argument definitions that
specify which particular operation to generate
templates for.
Returns:
list(DataTemplate) : Datatemplates that define this
JUMP_IF_EQ_ZERO.
"""
data_templates = []
data_templates.extend(generate_false_datatemplates(signature))
data_templates.extend(generate_true_datatemplates(signature))
return data_templates
[docs]def generate_false_datatemplates(signature):
"""
Create DataTemplates to define a conditional jump if condition is
false.
This is the case where no jump happens.
Args:
signature (list(dict)): List of argument definitions that
specify which particular operation to generate
templates for.
Returns:
list(DataTemplate) : Datatemplates that define the "false half"
of the operation.
"""
control_steps = generate_nonconditional_steps(signature)
jump_step_0 = [
MODULE_CONTROL["PC"]["COUNT"],
]
control_steps.append(jump_step_0)
instruction_byte_bitdefs = generate_instruction_byte_bitdefs(signature)
flags_bitdefs = [FLAGS["ZERO"]["LOW"]]
return assemble_instruction(
instruction_byte_bitdefs, flags_bitdefs, control_steps
)
[docs]def generate_nonconditional_steps(signature):
"""
Generate the nonconditional control steps.
These steps generate the flags which then govern whether the jump
happens or not.
Args:
signature (list(dict)): List of argument definitions that
specify which particular operation to generate steps for.
Returns:
list(list(str)) : List of list of bitdefs that represent the
steps, and the control signals at each step.
"""
control_steps = []
gen_flags_step_0 = [
MODULE_CONTROL[signature[0]["value"]]["OUT"],
MODULE_CONTROL["ALU"]["A_IS_BUS"],
MODULE_CONTROL["ALU"]["STORE_FLAGS"],
]
gen_flags_step_0.extend(ALU_CONTROL_FLAGS["A"])
control_steps.append(gen_flags_step_0)
return 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 operation to generate
the instruction byte bitdefs for.
Returns:
list(str): Bitdefs that make up the instruction_byte
"""
return [
INSTRUCTION_GROUPS["STORE"],
SRC_REGISTERS["SP"],
DEST_REGISTERS[signature[0]["value"]],
]
[docs]def generate_true_datatemplates(signature):
"""
Create DataTemplates to define a conditional jump if condition is true.
This is the case where no jump happens
Args:
signature (list(dict)): List of argument definitions that
specify which particular operation to generate
templates for.
Returns:
list(DataTemplate) : Datatemplates that define the "true half"
of a JUMP_IF_***_ACC operation.
"""
control_steps = generate_nonconditional_steps(signature)
# Now do the jump
jump_step_0 = [
MODULE_CONTROL["PC"]["OUT"],
MODULE_CONTROL["MAR"]["IN"],
]
control_steps.append(jump_step_0)
jump_step_1 = [
MODULE_CONTROL["RAM"]["SEL_PROG_MEM"],
MODULE_CONTROL["RAM"]["OUT"],
MODULE_CONTROL["PC"]["IN"],
]
control_steps.append(jump_step_1)
instruction_byte_bitdefs = generate_instruction_byte_bitdefs(signature)
flags_bitdefs = [FLAGS["ZERO"]["HIGH"]]
return assemble_instruction(
instruction_byte_bitdefs, flags_bitdefs, control_steps
)
[docs]def parse_line(line):
"""
Parse a line of assembly code to create machine code byte templates.
If a line is not identifiably an JUMP_IF_EQ_ZERO 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_bitstring = instruction_byte_from_bitdefs(
generate_instruction_byte_bitdefs(signature)
)
mc_bytes = []
instruction_byte = get_machine_code_byte_template()
instruction_byte["byte_type"] = "instruction"
instruction_byte["bitstring"] = instruction_byte_bitstring
mc_bytes.append(instruction_byte)
jump_target_byte = get_machine_code_byte_template()
jump_target_byte["byte_type"] = "constant"
jump_target_byte["constant"] = signature[1]["value"]
mc_bytes.append(jump_target_byte)
return mc_bytes