ch65/tools/gendispatch.py

import sys
import pprint
import dataclasses

import pyparsing as pp
import click

pp.ParserElement.set_default_whitespace_chars(" \t")

newline = pp.Word("\r\n").suppress()

comment = pp.Group(pp.Literal("#") + ... + newline).suppress()

blank = newline

prologue = (comment | blank)[...]  # (comment | blank)[...]

heading = pp.Literal("[").suppress() + ... + pp.Literal("]").suppress() + newline

statement = pp.Group(pp.Word(pp.alphanums + "(-") + ... + newline)

operand = pp.Word(pp.alphanums + "()#")

accumulator = pp.Literal("A")
immediate = pp.Literal("#d8")
zp = pp.Literal("a8")
x_ind_zp = pp.Literal("a8,X")
y_ind_zp = pp.Literal("a8,Y")
x_ind_zp_ind = pp.Literal("(a8,X)")
zp_ind_y_ind = pp.Literal("(a8),Y")
absolute = pp.Literal("a16")
x_ind_absolute = pp.Literal("a16,X")
y_ind_absolute = pp.Literal("a16,Y")
absolute_ind = pp.Literal("(a16)")
relative = pp.Literal("r8")

mode = (
    accumulator
    | immediate
    | x_ind_zp
    | y_ind_zp
    | zp
    | x_ind_zp_ind
    | zp_ind_y_ind
    | x_ind_absolute
    | y_ind_absolute
    | absolute
    | absolute_ind
    | relative
)

opcode = pp.Group(pp.common.hex_integer + pp.Word(pp.alphas) + pp.Opt(mode) + newline)

body = (comment | opcode | statement | blank)[...]

section = pp.Group(heading + body)

doc = prologue + section[...]


@dataclasses.dataclass
class Instruction:
    opcode: str
    operands: list[str]
    bytes: list[int]


_RESERVED = ("and", "or", "xor")


def cname(name: str) -> str:
    name = (
        name.lower()
        .replace("(", "")
        .replace("#", "")
        .replace(")", "i")
        .replace(",", "_")
        .replace("+", "_")
        .replace("'", "p")
    )
    if name in _RESERVED:
        return name + "_"
    return name


def func_name(instruction: Instruction) -> str:
    parts = [instruction.opcode] + instruction.operands
    return cname("_".join(parts))


def remap_operand(operands: list[str]):
    if not operands:
        return ""
    elif operands == ["A"]:
        return "regs.a"
    return f"{cname('_'.join(operands))}()"


def parse(opcodes: list):
    for ops in opcodes:
        top = doc.parse_file(ops, parse_all=True).as_list()
        for section in top:
            if section[0] == "opcodes":
                for opcode in section[1:]:
                    if isinstance(opcode[0], int):
                        yield Instruction(
                            opcode=opcode[1],
                            operands=[opcode[2]] if len(opcode) > 2 else [],
                            bytes=[opcode[0]],
                        )


def goto_prefix(emit):
    emit(
        """#pragma once

    #include "cores/w65c02v1.h"

    template<typename Board>
    void W65C02v1<Board>::run() {
    """
    )


def goto_dispatch(emit, top: list[Instruction]):
    by_bytes = {}
    for instruction in top:
        by_bytes[instruction.bytes[0]] = instruction
    emit(f"static const void* const dispatch[] = {{")
    for i in range(256):
        if i in by_bytes:
            emit(f"&&_{func_name(by_bytes[i])},")
        else:
            emit(f"&&_illegal,")
    emit("};")


def goto_suffix(emit):
    emit(
        """
    _illegal:
        illegal();
        }
    """
    )

USE_NEXT = False

def goto_implement(emit, top):
    goto_prefix(emit)
    goto_dispatch(emit, top)
    if USE_NEXT:
        emit("_next:")
    emit("goto *dispatch[fetch()];")
    for instruction in top:
        emit(
            f"""_{func_name(instruction)}:
            {cname(instruction.opcode)}({remap_operand(instruction.operands)});"""
        )
        if USE_NEXT:
            emit("goto _next;")
        else:
            emit("goto *dispatch[fetch()];")
    goto_suffix(emit)


@click.command()
@click.option("--opcodes", required=True, multiple=True, type=click.File(mode="r"))
@click.option("--out", required=True, type=click.File(mode="w", lazy=True, atomic=True))
def main(opcodes: list, out):
    def emit(*args):
        print(*args, file=out)

    goto_implement(emit, list(parse(opcodes)))


if __name__ == "__main__":
    main()