#!/usr/bin/env python
# lib9p/idl.gen - Generate C marshalers/unmarshalers for .9p files
#                 defining 9P protocol variants.
#
# Copyright (C) 2024-2025  Luke T. Shumaker <lukeshu@lukeshu.com>
# SPDX-License-Identifier: AGPL-3.0-or-later

import enum
import graphlib
import os.path
import sys
import typing

sys.path.insert(0, os.path.normpath(os.path.join(__file__, "..")))

import idl

# This strives to be "general-purpose" in that it just acts on the
# *.9p inputs; but (unfortunately?) there are a few special-cases in
# this script, marked with "SPECIAL".


# Utilities ####################################################################

idprefix = "lib9p_"

u32max = (1 << 32) - 1
u64max = (1 << 64) - 1


def tab_ljust(s: str, width: int) -> str:
    cur = len(s.expandtabs(tabsize=8))
    if cur >= width:
        return s
    return s + " " * (width - cur)


def add_prefix(p: str, s: str) -> str:
    if s.startswith("_"):
        return "_" + p + s[1:]
    return p + s


def c_macro(full: str) -> str:
    full = full.rstrip()
    assert "\n" in full
    lines = [l.rstrip() for l in full.split("\n")]
    width = max(len(l.expandtabs(tabsize=8)) for l in lines[:-1])
    lines = [tab_ljust(l, width) for l in lines]
    return "  \\\n".join(lines).rstrip() + "\n"


def c_ver_enum(ver: str) -> str:
    return f"{idprefix.upper()}VER_{ver.replace('.', '_')}"


def c_ver_ifdef(versions: typing.Collection[str]) -> str:
    return " || ".join(
        f"CONFIG_9P_ENABLE_{v.replace('.', '_')}" for v in sorted(versions)
    )


def c_ver_cond(versions: typing.Collection[str]) -> str:
    if len(versions) == 1:
        v = next(v for v in versions)
        return f"is_ver(ctx, {v.replace('.', '_')})"
    return "( " + (" || ".join(c_ver_cond({v}) for v in sorted(versions))) + " )"


def c_typename(typ: idl.Type, parent: idl.StructMember | None = None) -> str:
    match typ:
        case idl.Primitive():
            if typ.value == 1 and parent and parent.cnt:  # SPECIAL (string)
                return "[[gnu::nonstring]] char"
            return f"uint{typ.value*8}_t"
        case idl.Number():
            return f"{idprefix}{typ.name}_t"
        case idl.Bitfield():
            return f"{idprefix}{typ.name}_t"
        case idl.Message():
            return f"struct {idprefix}msg_{typ.name}"
        case idl.Struct():
            return f"struct {idprefix}{typ.name}"
        case _:
            raise ValueError(f"not a type: {typ.__class__.__name__}")


def c_expr(expr: idl.Expr, lookup_sym: typing.Callable[[str], str]) -> str:
    ret: list[str] = []
    for tok in expr.tokens:
        match tok:
            case idl.ExprOp():
                ret.append(tok.op)
            case idl.ExprLit():
                ret.append(str(tok.val))
            case idl.ExprSym(name="s32_max"):
                ret.append("INT32_MAX")
            case idl.ExprSym(name="s64_max"):
                ret.append("INT64_MAX")
            case idl.ExprSym():
                ret.append(lookup_sym(tok.name))
            case _:
                assert False
    return " ".join(ret)


_ifdef_stack: list[str | None] = []


def ifdef_push(n: int, _newval: str) -> str:
    # Grow the stack as needed
    global _ifdef_stack
    while len(_ifdef_stack) < n:
        _ifdef_stack.append(None)

    # Set some variables
    parentval: str | None = None
    for x in _ifdef_stack[:-1]:
        if x is not None:
            parentval = x
    oldval = _ifdef_stack[-1]
    newval: str | None = _newval
    if newval == parentval:
        newval = None

    # Put newval on the stack.
    _ifdef_stack[-1] = newval

    # Build output.
    ret = ""
    if newval != oldval:
        if oldval is not None:
            ret += f"#endif /* {oldval} */\n"
        if newval is not None:
            ret += f"#if {newval}\n"
    return ret


def ifdef_pop(n: int) -> str:
    global _ifdef_stack
    ret = ""
    while len(_ifdef_stack) > n:
        if _ifdef_stack[-1] is not None:
            ret += f"#endif /* {_ifdef_stack[-1]} */\n"
        _ifdef_stack = _ifdef_stack[:-1]
    return ret


# topo_sorted() ################################################################


def topo_sorted(typs: list[idl.Type]) -> typing.Iterable[idl.Type]:
    ts: graphlib.TopologicalSorter[idl.Type] = graphlib.TopologicalSorter()
    for typ in typs:
        match typ:
            case idl.Number():
                ts.add(typ)
            case idl.Bitfield():
                ts.add(typ)
            case idl.Struct():  # and idl.Message():
                deps = [
                    member.typ
                    for member in typ.members
                    if not isinstance(member.typ, idl.Primitive)
                ]
                ts.add(typ, *deps)
    return ts.static_order()


# walk() #######################################################################


class Path:
    root: idl.Type
    elems: list[idl.StructMember]

    def __init__(
        self, root: idl.Type, elems: list[idl.StructMember] | None = None
    ) -> None:
        self.root = root
        self.elems = elems if elems is not None else []

    def add(self, elem: idl.StructMember) -> "Path":
        return Path(self.root, self.elems + [elem])

    def parent(self) -> "Path":
        return Path(self.root, self.elems[:-1])

    def c_str(self, base: str, loopdepth: int = 0) -> str:
        ret = base
        for i, elem in enumerate(self.elems):
            if i > 0:
                ret += "."
            ret += elem.name
            if elem.cnt:
                ret += f"[{chr(ord('i')+loopdepth)}]"
                loopdepth += 1
        return ret

    def __str__(self) -> str:
        return self.c_str(self.root.name + "->")


class WalkCmd(enum.Enum):
    KEEP_GOING = 1
    DONT_RECURSE = 2
    ABORT = 3


type WalkHandler = typing.Callable[
    [Path], tuple[WalkCmd, typing.Callable[[], None] | None]
]


def _walk(path: Path, handle: WalkHandler) -> WalkCmd:
    typ = path.elems[-1].typ if path.elems else path.root

    ret, atexit = handle(path)

    if isinstance(typ, idl.Struct):
        match ret:
            case WalkCmd.KEEP_GOING:
                for member in typ.members:
                    if _walk(path.add(member), handle) == WalkCmd.ABORT:
                        ret = WalkCmd.ABORT
                        break
            case WalkCmd.DONT_RECURSE:
                ret = WalkCmd.KEEP_GOING
            case WalkCmd.ABORT:
                ret = WalkCmd.ABORT
            case _:
                assert False, f"invalid cmd: {ret}"

    if atexit:
        atexit()
    return ret


def walk(typ: idl.Type, handle: WalkHandler) -> None:
    _walk(Path(typ), handle)


# get_buffer_size() ############################################################


class BufferSize:
    min_size: int  # really just here to sanity-check against typ.min_size(version)
    exp_size: int  # "expected" or max-reasonable size
    max_size: int  # really just here to sanity-check against typ.max_size(version)
    max_copy: int
    max_copy_extra: str
    max_iov: int
    max_iov_extra: str
    _starts_with_copy: bool
    _ends_with_copy: bool

    def __init__(self) -> None:
        self.min_size = 0
        self.exp_size = 0
        self.max_size = 0
        self.max_copy = 0
        self.max_copy_extra = ""
        self.max_iov = 0
        self.max_iov_extra = ""
        self._starts_with_copy = False
        self._ends_with_copy = False


def get_buffer_size(typ: idl.Type, version: str) -> BufferSize:
    assert isinstance(typ, idl.Primitive) or (version in typ.in_versions)

    ret = BufferSize()

    if not isinstance(typ, idl.Struct):
        assert typ.static_size
        ret.min_size = typ.static_size
        ret.exp_size = typ.static_size
        ret.max_size = typ.static_size
        ret.max_copy = typ.static_size
        ret.max_iov = 1
        ret._starts_with_copy = True
        ret._ends_with_copy = True
        return ret

    def handle(path: Path) -> tuple[WalkCmd, None]:
        nonlocal ret
        if path.elems:
            child = path.elems[-1]
            if version not in child.in_versions:
                return WalkCmd.DONT_RECURSE, None
            if child.cnt:
                if child.typ.static_size == 1:  # SPECIAL (zerocopy)
                    ret.max_iov += 1
                    # HEURISTIC: 27 for strings (max-strlen from 9P1), 8KiB for other data
                    ret.exp_size += 27 if child.name == "utf8" else 8192
                    ret.max_size += child.max_cnt
                    ret._ends_with_copy = False
                    return WalkCmd.DONT_RECURSE, None
                sub = get_buffer_size(child.typ, version)
                ret.exp_size += sub.exp_size * 16  # HEURISTIC: MAXWELEM
                ret.max_size += sub.max_size * child.max_cnt
                if child.name == "wname" and path.root.name in (
                    "Tsread",
                    "Tswrite",
                ):  # SPECIAL (9P2000.e)
                    assert ret._ends_with_copy
                    assert sub._starts_with_copy
                    assert not sub._ends_with_copy
                    ret.max_copy_extra = (
                        f" + (CONFIG_9P_MAX_9P2000_e_WELEM * {sub.max_copy})"
                    )
                    ret.max_iov_extra = (
                        f" + (CONFIG_9P_MAX_9P2000_e_WELEM * {sub.max_iov})"
                    )
                    ret.max_iov -= 1
                else:
                    ret.max_copy += sub.max_copy * child.max_cnt
                    if sub.max_iov == 1 and sub._starts_with_copy:  # is purely copy
                        ret.max_iov += 1
                    else:  # contains zero-copy segments
                        ret.max_iov += sub.max_iov * child.max_cnt
                    if ret._ends_with_copy and sub._starts_with_copy:
                        # we can merge this one
                        ret.max_iov -= 1
                    if (
                        sub._ends_with_copy
                        and sub._starts_with_copy
                        and sub.max_iov > 1
                    ):
                        # we can merge these
                        ret.max_iov -= child.max_cnt - 1
                ret._ends_with_copy = sub._ends_with_copy
                return WalkCmd.DONT_RECURSE, None
            elif not isinstance(child.typ, idl.Struct):
                assert child.typ.static_size
                if not ret._ends_with_copy:
                    if ret.max_size == 0:
                        ret._starts_with_copy = True
                    ret.max_iov += 1
                    ret._ends_with_copy = True
                ret.min_size += child.typ.static_size
                ret.exp_size += child.typ.static_size
                ret.max_size += child.typ.static_size
                ret.max_copy += child.typ.static_size
        return WalkCmd.KEEP_GOING, None

    walk(typ, handle)
    assert ret.min_size == typ.min_size(version)
    assert ret.max_size == typ.max_size(version)
    return ret


# Generate .h ##################################################################


def gen_h(versions: set[str], typs: list[idl.Type]) -> str:
    global _ifdef_stack
    _ifdef_stack = []

    ret = f"""/* Generated by `{' '.join(sys.argv)}`.  DO NOT EDIT!  */

#ifndef _LIB9P_9P_H_
\t#error Do not include <lib9p/9p.generated.h> directly; include <lib9p/9p.h> instead
#endif

#include <stdint.h> /* for uint{{n}}_t types */

#include <libhw/generic/net.h> /* for struct iovec */
"""

    id2typ: dict[int, idl.Message] = {}
    for msg in [msg for msg in typs if isinstance(msg, idl.Message)]:
        id2typ[msg.msgid] = msg

    ret += f"""
/* config *********************************************************************/

#include "config.h"
"""
    for ver in sorted(versions):
        ret += "\n"
        ret += f"#ifndef {c_ver_ifdef({ver})}\n"
        ret += f"\t#error config.h must define {c_ver_ifdef({ver})}\n"
        if ver == "9P2000.e":  # SPECIAL (9P2000.e)
            ret += "#else\n"
            ret += f"\t#if {c_ver_ifdef({ver})}\n"
            ret += "\t\t#ifndef(CONFIG_9P_MAX_9P2000_e_WELEM)\n"
            ret += f"\t\t\t#error if {c_ver_ifdef({ver})} then config.h must define CONFIG_9P_MAX_9P2000_e_WELEM\n"
            ret += "\t\t#endif\n"
            ret += "\t\tstatic_assert(CONFIG_9P_MAX_9P2000_e_WELEM > 0);\n"
            ret += "\t#endif\n"
        ret += "#endif\n"

    ret += f"""
/* enum version ***************************************************************/

enum {idprefix}version {{
"""
    fullversions = ["unknown = 0", *sorted(versions)]
    verwidth = max(len(v) for v in fullversions)
    for ver in fullversions:
        if ver in versions:
            ret += ifdef_push(1, c_ver_ifdef({ver}))
        ret += f"\t{c_ver_enum(ver)},"
        ret += (" " * (verwidth - len(ver))) + ' /* "' + ver.split()[0] + '" */\n'
    ret += ifdef_pop(0)
    ret += f"\t{c_ver_enum('NUM')},\n"
    ret += "};\n"

    ret += """
/* enum msg_type **************************************************************/

"""
    ret += f"enum {idprefix}msg_type {{ /* uint8_t */\n"
    namewidth = max(len(msg.name) for msg in typs if isinstance(msg, idl.Message))
    for n in range(0x100):
        if n not in id2typ:
            continue
        msg = id2typ[n]
        ret += ifdef_push(1, c_ver_ifdef(msg.in_versions))
        ret += f"\t{idprefix.upper()}TYP_{msg.name.ljust(namewidth)} = {msg.msgid},\n"
    ret += ifdef_pop(0)
    ret += "};\n"

    ret += """
/* payload types **************************************************************/
"""

    def per_version_comment(
        typ: idl.Type, fn: typing.Callable[[idl.Type, str], str]
    ) -> str:
        lines: dict[str, str] = {}
        for version in sorted(typ.in_versions):
            lines[version] = fn(typ, version)
        if len(set(lines.values())) == 1:
            for _, line in lines.items():
                return f"/* {line} */\n"
            assert False
        else:
            ret = ""
            v_width = max(len(c_ver_enum(v)) for v in typ.in_versions)
            for version, line in lines.items():
                ret += f"/* {c_ver_enum(version).ljust(v_width)}: {line} */\n"
            return ret

    for typ in topo_sorted(typs):
        ret += "\n"
        ret += ifdef_push(1, c_ver_ifdef(typ.in_versions))

        def sum_size(typ: idl.Type, version: str) -> str:
            sz = get_buffer_size(typ, version)
            assert (
                sz.min_size <= sz.exp_size
                and sz.exp_size <= sz.max_size
                and sz.max_size < u64max
            )
            ret = ""
            if sz.min_size == sz.max_size:
                ret += f"size = {sz.min_size:,}"
            else:
                ret += f"min_size = {sz.min_size:,} ; exp_size = {sz.exp_size:,} ; max_size = {sz.max_size:,}"
            if sz.max_size > u32max:
                ret += " (warning: >UINT32_MAX)"
            ret += f" ; max_iov = {sz.max_iov:,}{sz.max_iov_extra} ; max_copy = {sz.max_copy:,}{sz.max_copy_extra}"
            return ret

        ret += per_version_comment(typ, sum_size)

        match typ:
            case idl.Number():
                ret += f"typedef {c_typename(typ.prim)} {c_typename(typ)};\n"
                prefix = f"{idprefix.upper()}{typ.name.upper()}_"
                namewidth = max(len(name) for name in typ.vals)
                for name, val in typ.vals.items():
                    ret += f"#define {prefix}{name.ljust(namewidth)} (({c_typename(typ)})UINT{typ.static_size*8}_C({val}))\n"
            case idl.Bitfield():
                ret += f"typedef {c_typename(typ.prim)} {c_typename(typ)};\n"
                names = [
                    typ.bits[n] or f" {n}" for n in reversed(range(0, len(typ.bits)))
                ]
                if aliases := [k for k in typ.names if k not in typ.bits]:
                    names.append("")
                    names.extend(aliases)
                prefix = f"{idprefix.upper()}{typ.name.upper()}_"
                namewidth = max(len(add_prefix(prefix, name)) for name in names)

                ret += "\n"
                for name in names:
                    if name == "":
                        ret += "\n"
                        continue

                    if name.startswith(" "):
                        vers = typ.in_versions
                        c_name = ""
                        c_val = f"1<<{name[1:]}"
                    else:
                        vers = typ.names[name].in_versions
                        c_name = add_prefix(prefix, name)
                        c_val = f"{typ.names[name].val}"

                    ret += ifdef_push(2, c_ver_ifdef(vers))

                    # It is important all of the `beg` strings have
                    # the same length.
                    end = ""
                    if name.startswith(" "):
                        beg = "/* unused"
                        end = " */"
                    elif _ifdef_stack[-1]:
                        beg = "#  define"
                    else:
                        beg = "#define  "

                    ret += f"{beg} {c_name.ljust(namewidth)}  (({c_typename(typ)})({c_val})){end}\n"
                ret += ifdef_pop(1)
            case idl.Struct():  # and idl.Message():
                ret += c_typename(typ) + " {"
                if not typ.members:
                    ret += "};\n"
                    continue
                ret += "\n"

                typewidth = max(len(c_typename(m.typ, m)) for m in typ.members)

                for member in typ.members:
                    if member.val:
                        continue
                    ret += ifdef_push(2, c_ver_ifdef(member.in_versions))
                    ret += f"\t{c_typename(member.typ, member).ljust(typewidth)}  {'*' if member.cnt else ' '}{member.name};\n"
                ret += ifdef_pop(1)
                ret += "};\n"
    ret += ifdef_pop(0)

    ret += """
/* containers *****************************************************************/
"""
    ret += "\n"
    ret += f"#define _{idprefix.upper()}MAX(a, b) ((a) > (b)) ? (a) : (b)\n"

    tmsg_max_iov: dict[str, int] = {}
    tmsg_max_copy: dict[str, int] = {}
    rmsg_max_iov: dict[str, int] = {}
    rmsg_max_copy: dict[str, int] = {}
    for typ in typs:
        if not isinstance(typ, idl.Message):
            continue
        if typ.name in ("Tsread", "Tswrite"):  # SPECIAL (9P2000.e)
            continue
        max_iov = tmsg_max_iov if typ.msgid % 2 == 0 else rmsg_max_iov
        max_copy = tmsg_max_copy if typ.msgid % 2 == 0 else rmsg_max_copy
        for version in typ.in_versions:
            if version not in max_iov:
                max_iov[version] = 0
                max_copy[version] = 0
            sz = get_buffer_size(typ, version)
            if sz.max_iov > max_iov[version]:
                max_iov[version] = sz.max_iov
            if sz.max_copy > max_copy[version]:
                max_copy[version] = sz.max_copy

    for name, table in [
        ("tmsg_max_iov", tmsg_max_iov),
        ("tmsg_max_copy", tmsg_max_copy),
        ("rmsg_max_iov", rmsg_max_iov),
        ("rmsg_max_copy", rmsg_max_copy),
    ]:
        inv: dict[int, set[str]] = {}
        for version, maxval in table.items():
            if maxval not in inv:
                inv[maxval] = set()
            inv[maxval].add(version)

        ret += "\n"
        directive = "if"
        seen_e = False  # SPECIAL (9P2000.e)
        for maxval in sorted(inv, reverse=True):
            ret += f"#{directive} {c_ver_ifdef(inv[maxval])}\n"
            indent = 1
            if name.startswith("tmsg") and not seen_e:  # SPECIAL (9P2000.e)
                typ = next(typ for typ in typs if typ.name == "Tswrite")
                sz = get_buffer_size(typ, "9P2000.e")
                match name:
                    case "tmsg_max_iov":
                        maxexpr = f"{sz.max_iov}{sz.max_iov_extra}"
                    case "tmsg_max_copy":
                        maxexpr = f"{sz.max_copy}{sz.max_copy_extra}"
                    case _:
                        assert False
                ret += f"\t#if {c_ver_ifdef({"9P2000.e"})}\n"
                ret += f"\t\t#define {idprefix.upper()}{name.upper()} _{idprefix.upper()}MAX({maxval}, {maxexpr})\n"
                ret += f"\t#else\n"
                indent += 1
            ret += f"{'\t'*indent}#define {idprefix.upper()}{name.upper()} {maxval}\n"
            if name.startswith("tmsg") and not seen_e:  # SPECIAL (9P2000.e)
                ret += "\t#endif\n"
                if "9P2000.e" in inv[maxval]:
                    seen_e = True
            directive = "elif"
        ret += "#endif\n"

    ret += "\n"
    ret += f"struct {idprefix}Tmsg_send_buf {{\n"
    ret += f"\tsize_t          iov_cnt;\n"
    ret += f"\tstruct iovec    iov[{idprefix.upper()}TMSG_MAX_IOV];\n"
    ret += f"\tuint8_t         copied[{idprefix.upper()}TMSG_MAX_COPY];\n"
    ret += "};\n"

    ret += "\n"
    ret += f"struct {idprefix}Rmsg_send_buf {{\n"
    ret += f"\tsize_t          iov_cnt;\n"
    ret += f"\tstruct iovec    iov[{idprefix.upper()}RMSG_MAX_IOV];\n"
    ret += f"\tuint8_t         copied[{idprefix.upper()}RMSG_MAX_COPY];\n"
    ret += "};\n"

    return ret


# Generate .c ##################################################################


def gen_c(versions: set[str], typs: list[idl.Type]) -> str:
    global _ifdef_stack
    _ifdef_stack = []

    ret = f"""/* Generated by `{' '.join(sys.argv)}`.  DO NOT EDIT!  */

#include <stdbool.h>
#include <stddef.h>   /* for size_t */
#include <inttypes.h> /* for PRI* macros */
#include <string.h>   /* for memset() */

#include <libmisc/assert.h>

#include <lib9p/9p.h>

#include "internal.h"
"""

    # utilities ################################################################
    ret += f"""
/* utilities ******************************************************************/
"""

    def used(arg: str) -> str:
        return arg

    def unused(arg: str) -> str:
        return f"LM_UNUSED({arg})"

    id2typ: dict[int, idl.Message] = {}
    for msg in [msg for msg in typs if isinstance(msg, idl.Message)]:
        id2typ[msg.msgid] = msg

    def msg_table(grp: str, meth: str, tentry: str, rng: tuple[int, int, int]) -> str:
        ret = f"const {tentry} _{idprefix}table_{grp}_{meth}[{c_ver_enum('NUM')}][{hex(len(range(*rng)))}] = {{\n"
        for ver in ["unknown", *sorted(versions)]:
            if ver != "unknown":
                ret += ifdef_push(1, c_ver_ifdef({ver}))
            ret += f"\t[{c_ver_enum(ver)}] = {{\n"
            for n in range(*rng):
                xmsg: idl.Message | None = id2typ.get(n, None)
                if xmsg:
                    if ver == "unknown":  # SPECIAL (initialization)
                        if xmsg.name not in ["Tversion", "Rversion", "Rerror"]:
                            xmsg = None
                    else:
                        if ver not in xmsg.in_versions:
                            xmsg = None
                if xmsg:
                    ret += f"\t\t_MSG_{meth.upper()}({xmsg.name}),\n"
            ret += "\t},\n"
        ret += ifdef_pop(0)
        ret += "};\n"
        return ret

    for v in sorted(versions):
        ret += f"#if CONFIG_9P_ENABLE_{v.replace('.', '_')}\n"
        ret += f"\t#define _is_ver_{v.replace('.', '_')}(v) (v == {c_ver_enum(v)})\n"
        ret += "#else\n"
        ret += f"\t#define _is_ver_{v.replace('.', '_')}(v) false\n"
        ret += "#endif\n"
    ret += "\n"
    ret += "/**\n"
    ret += f" * is_ver(ctx, ver) is essentially `(ctx->ctx->version == {idprefix.upper()}VER_##ver)`,\n"
    ret += f" * but compiles correctly (to `false`) even if `{idprefix.upper()}VER_##ver` isn't defined\n"
    ret += " * (because `!CONFIG_9P_ENABLE_##ver`).  This is useful when `||`ing\n"
    ret += " * several version checks together.\n"
    ret += " */\n"
    ret += "#define is_ver(CTX, ver) _is_ver_##ver(CTX->ctx->version)\n"

    # strings ##################################################################
    ret += f"""
/* strings ********************************************************************/

const char *const _{idprefix}table_ver_name[{c_ver_enum('NUM')}] = {{
"""
    for ver in ["unknown", *sorted(versions)]:
        if ver in versions:
            ret += ifdef_push(1, c_ver_ifdef({ver}))
        ret += f'\t[{c_ver_enum(ver)}] = "{ver}",\n'
    ret += ifdef_pop(0)
    ret += "};\n"

    ret += "\n"
    ret += f"#define _MSG_NAME(typ) [{idprefix.upper()}TYP_##typ] = #typ\n"
    ret += msg_table("msg", "name", "char *const", (0, 0x100, 1))

    # bitmasks #################################################################
    ret += f"""
/* bitmasks *******************************************************************/
"""
    for typ in typs:
        if not isinstance(typ, idl.Bitfield):
            continue
        ret += "\n"
        ret += ifdef_push(1, c_ver_ifdef(typ.in_versions))
        ret += f"static const {c_typename(typ)} {typ.name}_masks[{c_ver_enum('NUM')}] = {{\n"
        verwidth = max(len(ver) for ver in versions)
        for ver in sorted(versions):
            ret += ifdef_push(2, c_ver_ifdef({ver}))
            ret += (
                f"\t[{c_ver_enum(ver)}]{' '*(verwidth-len(ver))} = 0b"
                + "".join(
                    "1" if typ.bit_is_valid(bitname, ver) else "0"
                    for bitname in reversed(typ.bits)
                )
                + ",\n"
            )
        ret += ifdef_pop(1)
        ret += "};\n"
    ret += ifdef_pop(0)

    # validate_* ###############################################################
    ret += """
/* validate_* *****************************************************************/

LM_ALWAYS_INLINE static bool _validate_size_net(struct _validate_ctx *ctx, uint32_t n) {
\tif (__builtin_add_overflow(ctx->net_offset, n, &ctx->net_offset))
\t\t/* If needed-net-size overflowed uint32_t, then
\t\t * there's no way that actual-net-size will live up to
\t\t * that.  */
\t\treturn lib9p_error(ctx->ctx, LINUX_EBADMSG, "message is too short for content");
\tif (ctx->net_offset > ctx->net_size)
\t\treturn lib9p_error(ctx->ctx, LINUX_EBADMSG, "message is too short for content");
\treturn false;
}

LM_ALWAYS_INLINE static bool _validate_size_host(struct _validate_ctx *ctx, size_t n) {
\tif (__builtin_add_overflow(ctx->host_extra, n, &ctx->host_extra))
\t\t/* If needed-host-size overflowed size_t, then there's
\t\t * no way that actual-net-size will live up to
\t\t * that.  */
\t\treturn lib9p_error(ctx->ctx, LINUX_EBADMSG, "message is too short for content");
\treturn false;
}

LM_ALWAYS_INLINE static bool _validate_list(struct _validate_ctx *ctx,
                                         size_t cnt,
                                         _validate_fn_t item_fn, size_t item_host_size) {
\tfor (size_t i = 0; i < cnt; i++)
\t\tif (_validate_size_host(ctx, item_host_size) || item_fn(ctx))
\t\t\treturn true;
\treturn false;
}

LM_ALWAYS_INLINE static bool validate_1(struct _validate_ctx *ctx) { return _validate_size_net(ctx, 1); }
LM_ALWAYS_INLINE static bool validate_2(struct _validate_ctx *ctx) { return _validate_size_net(ctx, 2); }
LM_ALWAYS_INLINE static bool validate_4(struct _validate_ctx *ctx) { return _validate_size_net(ctx, 4); }
LM_ALWAYS_INLINE static bool validate_8(struct _validate_ctx *ctx) { return _validate_size_net(ctx, 8); }
"""
    for typ in topo_sorted(typs):
        inline = "LM_FLATTEN" if isinstance(typ, idl.Message) else "LM_ALWAYS_INLINE"
        argfn = unused if (isinstance(typ, idl.Struct) and not typ.members) else used
        ret += "\n"
        ret += ifdef_push(1, c_ver_ifdef(typ.in_versions))
        ret += f"{inline} static bool validate_{typ.name}(struct _validate_ctx *{argfn('ctx')}) {{\n"

        match typ:
            case idl.Number():
                ret += f"\treturn validate_{typ.prim.name}(ctx);\n"
            case idl.Bitfield():
                ret += f"\t if (validate_{typ.static_size}(ctx))\n"
                ret += "\t\treturn true;\n"
                ret += (
                    f"\t{c_typename(typ)} mask = {typ.name}_masks[ctx->ctx->version];\n"
                )
                if typ.static_size == 1:
                    ret += f"\t{c_typename(typ)} val = ctx->net_bytes[ctx->net_offset-1];\n"
                else:
                    ret += f"\t{c_typename(typ)} val = uint{typ.static_size*8}le_decode(&ctx->net_bytes[ctx->net_offset-{typ.static_size}]);\n"
                ret += f"\tif (val & ~mask)\n"
                ret += f'\t\treturn lib9p_errorf(ctx->ctx, LINUX_EBADMSG, "unknown bits in {typ.name} bitfield: %#0{typ.static_size}"PRIx{typ.static_size*8}, val & ~mask);\n'
                ret += "\treturn false;\n"
            case idl.Struct():  # and idl.Message()
                if len(typ.members) == 0:
                    ret += "\treturn false;\n"
                    ret += "}\n"
                    continue

                def should_save_value(member: idl.StructMember) -> bool:
                    nonlocal typ
                    assert isinstance(typ, idl.Struct)
                    return bool(
                        member.max
                        or member.val
                        or any(m.cnt == member for m in typ.members)
                    )

                # Pass 1 - declare value variables
                for member in typ.members:
                    if should_save_value(member):
                        ret += ifdef_push(2, c_ver_ifdef(member.in_versions))
                        ret += f"\t{c_typename(member.typ)} {member.name};\n"
                ret += ifdef_pop(1)

                # Pass 2 - declare offset variables
                mark_offset: set[str] = set()
                for member in typ.members:
                    for tok in [*member.max.tokens, *member.val.tokens]:
                        if isinstance(tok, idl.ExprSym) and tok.name.startswith("&"):
                            if tok.name[1:] not in mark_offset:
                                ret += f"\tuint32_t _{tok.name[1:]}_offset;\n"
                            mark_offset.add(tok.name[1:])

                # Pass 3 - main pass
                ret += "\treturn false\n"
                for member in typ.members:
                    ret += ifdef_push(2, c_ver_ifdef(member.in_versions))
                    ret += f"\t    || "
                    if member.in_versions != typ.in_versions:
                        ret += "( " + c_ver_cond(member.in_versions) + " && "
                    if member.cnt is not None:
                        if member.typ.static_size == 1:  # SPECIAL (zerocopy)
                            ret += f"_validate_size_net(ctx, {member.cnt.name})"
                        else:
                            ret += f"_validate_list(ctx, {member.cnt.name}, validate_{member.typ.name}, sizeof({c_typename(member.typ)}))"
                        if typ.name == "s":  # SPECIAL (string)
                            ret += f'\n\t    || ({{ (!is_valid_utf8_without_nul(&ctx->net_bytes[ctx->net_offset-len], len)) && lib9p_error(ctx->ctx, LINUX_EBADMSG, "message contains invalid UTF-8"); }})'
                    else:
                        if should_save_value(member):
                            ret += "("
                        if member.name in mark_offset:
                            ret += f"({{ _{member.name}_offset = ctx->net_offset; "
                        ret += f"validate_{member.typ.name}(ctx)"
                        if member.name in mark_offset:
                            ret += "; })"
                        if should_save_value(member):
                            nbytes = member.static_size
                            assert nbytes
                            if nbytes == 1:
                                ret += f" || ({{ {member.name} = ctx->net_bytes[ctx->net_offset-1]; false; }}))"
                            else:
                                ret += f" || ({{ {member.name} = uint{nbytes*8}le_decode(&ctx->net_bytes[ctx->net_offset-{nbytes}]); false; }}))"
                    if member.in_versions != typ.in_versions:
                        ret += " )"
                    ret += "\n"

                # Pass 4 - validate ,max= and ,val= constraints
                for member in typ.members:

                    def lookup_sym(sym: str) -> str:
                        match sym:
                            case "end":
                                return "ctx->net_offset"
                            case _:
                                assert sym.startswith("&")
                                return f"_{sym[1:]}_offset"

                    if member.max:
                        assert member.static_size
                        nbits = member.static_size * 8
                        ret += ifdef_push(2, c_ver_ifdef(member.in_versions))
                        ret += f"\t    || ({{ uint{nbits}_t max = {c_expr(member.max, lookup_sym)}; (((uint{nbits}_t){member.name}) > max) &&\n"
                        ret += f'\t          lib9p_errorf(ctx->ctx, LINUX_EBADMSG, "{member.name} value is too large (%"PRIu{nbits}" > %"PRIu{nbits}")", {member.name}, max); }})\n'
                    if member.val:
                        assert member.static_size
                        nbits = member.static_size * 8
                        ret += ifdef_push(2, c_ver_ifdef(member.in_versions))
                        ret += f"\t    || ({{ uint{nbits}_t exp = {c_expr(member.val, lookup_sym)}; (((uint{nbits}_t){member.name}) != exp) &&\n"
                        ret += f'\t          lib9p_errorf(ctx->ctx, LINUX_EBADMSG, "{member.name} value is wrong (actual:%"PRIu{nbits}" != correct:%"PRIu{nbits}")", (uint{nbits}_t){member.name}, exp); }})\n'

                ret += ifdef_pop(1)
                ret += "\t    ;\n"
        ret += "}\n"
    ret += ifdef_pop(0)

    # unmarshal_* ##############################################################
    ret += """
/* unmarshal_* ****************************************************************/

LM_ALWAYS_INLINE static void unmarshal_1(struct _unmarshal_ctx *ctx, uint8_t *out) {
\t*out = ctx->net_bytes[ctx->net_offset];
\tctx->net_offset += 1;
}

LM_ALWAYS_INLINE static void unmarshal_2(struct _unmarshal_ctx *ctx, uint16_t *out) {
\t*out = uint16le_decode(&ctx->net_bytes[ctx->net_offset]);
\tctx->net_offset += 2;
}

LM_ALWAYS_INLINE static void unmarshal_4(struct _unmarshal_ctx *ctx, uint32_t *out) {
\t*out = uint32le_decode(&ctx->net_bytes[ctx->net_offset]);
\tctx->net_offset += 4;
}

LM_ALWAYS_INLINE static void unmarshal_8(struct _unmarshal_ctx *ctx, uint64_t *out) {
\t*out = uint64le_decode(&ctx->net_bytes[ctx->net_offset]);
\tctx->net_offset += 8;
}
"""
    for typ in topo_sorted(typs):
        inline = "LM_FLATTEN" if isinstance(typ, idl.Message) else "LM_ALWAYS_INLINE"
        argfn = unused if (isinstance(typ, idl.Struct) and not typ.members) else used
        ret += "\n"
        ret += ifdef_push(1, c_ver_ifdef(typ.in_versions))
        ret += f"{inline} static void unmarshal_{typ.name}(struct _unmarshal_ctx *{argfn('ctx')}, {c_typename(typ)} *out) {{\n"
        match typ:
            case idl.Number():
                ret += f"\tunmarshal_{typ.prim.name}(ctx, ({c_typename(typ.prim)} *)out);\n"
            case idl.Bitfield():
                ret += f"\tunmarshal_{typ.prim.name}(ctx, ({c_typename(typ.prim)} *)out);\n"
            case idl.Struct():
                ret += "\tmemset(out, 0, sizeof(*out));\n"

                for member in typ.members:
                    ret += ifdef_push(2, c_ver_ifdef(member.in_versions))
                    if member.val:
                        ret += f"\tctx->net_offset += {member.static_size};\n"
                        continue
                    ret += "\t"

                    prefix = "\t"
                    if member.in_versions != typ.in_versions:
                        ret += "if ( " + c_ver_cond(member.in_versions) + " ) "
                        prefix = "\t\t"
                    if member.cnt:
                        if member.in_versions != typ.in_versions:
                            ret += "{\n"
                            ret += prefix
                        if member.typ.static_size == 1:  # SPECIAL (string, zerocopy)
                            ret += f"out->{member.name} = (char *)&ctx->net_bytes[ctx->net_offset];\n"
                            ret += (
                                f"{prefix}ctx->net_offset += out->{member.cnt.name};\n"
                            )
                        else:
                            ret += f"out->{member.name} = ctx->extra;\n"
                            ret += f"{prefix}ctx->extra += sizeof(out->{member.name}[0]) * out->{member.cnt.name};\n"
                            ret += f"{prefix}for (typeof(out->{member.cnt.name}) i = 0; i < out->{member.cnt.name}; i++)\n"
                            ret += f"{prefix}\tunmarshal_{member.typ.name}(ctx, &out->{member.name}[i]);\n"
                        if member.in_versions != typ.in_versions:
                            ret += "\t}\n"
                    else:
                        ret += (
                            f"unmarshal_{member.typ.name}(ctx, &out->{member.name});\n"
                        )
        ret += ifdef_pop(1)
        ret += "}\n"
    ret += ifdef_pop(0)

    # marshal_* ################################################################
    ret += """
/* marshal_* ******************************************************************/

"""
    ret += c_macro(
        "#define MARSHAL_BYTES_ZEROCOPY(ctx, data, len)\n"
        "\tif (ctx->net_iov[ctx->net_iov_cnt-1].iov_len)\n"
        "\t\tctx->net_iov_cnt++;\n"
        "\tctx->net_iov[ctx->net_iov_cnt-1].iov_base = data;\n"
        "\tctx->net_iov[ctx->net_iov_cnt-1].iov_len = len;\n"
        "\tctx->net_iov_cnt++;\n"
    )
    ret += c_macro(
        "#define MARSHAL_BYTES(ctx, data, len)\n"
        "\tif (!ctx->net_iov[ctx->net_iov_cnt-1].iov_base)\n"
        "\t\tctx->net_iov[ctx->net_iov_cnt-1].iov_base = &ctx->net_copied[ctx->net_copied_size];\n"
        "\tmemcpy(&ctx->net_copied[ctx->net_copied_size], data, len);\n"
        "\tctx->net_copied_size += len;\n"
        "\tctx->net_iov[ctx->net_iov_cnt-1].iov_len += len;\n"
    )
    ret += c_macro(
        "#define MARSHAL_U8LE(ctx, val)\n"
        "\tif (!ctx->net_iov[ctx->net_iov_cnt-1].iov_base)\n"
        "\t\tctx->net_iov[ctx->net_iov_cnt-1].iov_base = &ctx->net_copied[ctx->net_copied_size];\n"
        "\tctx->net_copied[ctx->net_copied_size] = val;\n"
        "\tctx->net_copied_size += 1;\n"
        "\tctx->net_iov[ctx->net_iov_cnt-1].iov_len += 1;\n"
    )
    ret += c_macro(
        "#define MARSHAL_U16LE(ctx, val)\n"
        "\tif (!ctx->net_iov[ctx->net_iov_cnt-1].iov_base)\n"
        "\t\tctx->net_iov[ctx->net_iov_cnt-1].iov_base = &ctx->net_copied[ctx->net_copied_size];\n"
        "\tuint16le_encode(&ctx->net_copied[ctx->net_copied_size], val);\n"
        "\tctx->net_copied_size += 2;\n"
        "\tctx->net_iov[ctx->net_iov_cnt-1].iov_len += 2;\n"
    )
    ret += c_macro(
        "#define MARSHAL_U32LE(ctx, val)\n"
        "\tif (!ctx->net_iov[ctx->net_iov_cnt-1].iov_base)\n"
        "\t\tctx->net_iov[ctx->net_iov_cnt-1].iov_base = &ctx->net_copied[ctx->net_copied_size];\n"
        "\tuint32le_encode(&ctx->net_copied[ctx->net_copied_size], val);\n"
        "\tctx->net_copied_size += 4;\n"
        "\tctx->net_iov[ctx->net_iov_cnt-1].iov_len += 4;\n"
    )
    ret += c_macro(
        "#define MARSHAL_U64LE(ctx, val)\n"
        "\tif (!ctx->net_iov[ctx->net_iov_cnt-1].iov_base)\n"
        "\t\tctx->net_iov[ctx->net_iov_cnt-1].iov_base = &ctx->net_copied[ctx->net_copied_size];\n"
        "\tuint64le_encode(&ctx->net_copied[ctx->net_copied_size], val);\n"
        "\tctx->net_copied_size += 8;\n"
        "\tctx->net_iov[ctx->net_iov_cnt-1].iov_len += 8;\n"
    )

    class OffsetExpr:
        static: int
        cond: dict[frozenset[str], "OffsetExpr"]
        rep: list[tuple[Path, "OffsetExpr"]]

        def __init__(self) -> None:
            self.static = 0
            self.rep = []
            self.cond = {}

        def add(self, other: "OffsetExpr") -> None:
            self.static += other.static
            self.rep += other.rep
            for k, v in other.cond.items():
                if k in self.cond:
                    self.cond[k].add(v)
                else:
                    self.cond[k] = v

        def gen_c(
            self,
            dsttyp: str,
            dstvar: str,
            root: str,
            indent_depth: int,
            loop_depth: int,
        ) -> str:
            oneline: list[str] = []
            multiline = ""
            if self.static:
                oneline.append(str(self.static))
            for cnt, sub in self.rep:
                if not sub.cond and not sub.rep:
                    if sub.static == 1:
                        oneline.append(cnt.c_str(root))
                    else:
                        oneline.append(f"({cnt.c_str(root)})*{sub.static}")
                    continue
                loopvar = chr(ord("i") + loop_depth)
                multiline += f"{'\t'*indent_depth}for ({c_typename(cnt.elems[-1].typ)} {loopvar} = 0; {loopvar} < {cnt.c_str(root)}; {loopvar}++) {{\n"
                multiline += sub.gen_c(
                    "", dstvar, root, indent_depth + 1, loop_depth + 1
                )
                multiline += f"{'\t'*indent_depth}}}\n"
            for vers, sub in self.cond.items():
                multiline += ifdef_push(indent_depth + 1, c_ver_ifdef(vers))
                multiline += f"{'\t'*indent_depth}if {c_ver_cond(vers)} {{\n"
                multiline += sub.gen_c("", dstvar, root, indent_depth + 1, loop_depth)
                multiline += f"{'\t'*indent_depth}}}\n"
                multiline += ifdef_pop(indent_depth)
            if dsttyp:
                if not oneline:
                    oneline.append("0")
                ret = f"{'\t'*indent_depth}{dsttyp} {dstvar} = {' + '.join(oneline)};\n"
            elif oneline:
                ret = f"{'\t'*indent_depth}{dstvar} += {' + '.join(oneline)};\n"
            ret += multiline
            return ret

    type OffsetExprRecursion = typing.Callable[[Path], WalkCmd]

    def get_offset_expr(typ: idl.Type, recurse: OffsetExprRecursion) -> OffsetExpr:
        if not isinstance(typ, idl.Struct):
            assert typ.static_size
            ret = OffsetExpr()
            ret.static = typ.static_size
            return ret

        stack: list[tuple[Path, OffsetExpr, typing.Callable[[], None]]]

        def pop_root() -> None:
            assert False

        def pop_cond() -> None:
            nonlocal stack
            key = frozenset(stack[-1][0].elems[-1].in_versions)
            if key in stack[-2][1].cond:
                stack[-2][1].cond[key].add(stack[-1][1])
            else:
                stack[-2][1].cond[key] = stack[-1][1]
            stack = stack[:-1]

        def pop_rep() -> None:
            nonlocal stack
            member_path = stack[-1][0]
            member = member_path.elems[-1]
            assert member.cnt
            cnt_path = member_path.parent().add(member.cnt)
            stack[-2][1].rep.append((cnt_path, stack[-1][1]))
            stack = stack[:-1]

        def handle(path: Path) -> tuple[WalkCmd, typing.Callable[[], None] | None]:
            nonlocal recurse

            ret = recurse(path)
            if ret != WalkCmd.KEEP_GOING:
                return ret, None

            nonlocal stack
            stack_len = len(stack)

            def pop() -> None:
                nonlocal stack
                nonlocal stack_len
                while len(stack) > stack_len:
                    stack[-1][2]()

            if path.elems:
                child = path.elems[-1]
                parent = path.elems[-2].typ if len(path.elems) > 1 else path.root
                if child.in_versions < parent.in_versions:
                    stack.append((path, OffsetExpr(), pop_cond))
                if child.cnt:
                    stack.append((path, OffsetExpr(), pop_rep))
                if not isinstance(child.typ, idl.Struct):
                    assert child.typ.static_size
                    stack[-1][1].static += child.typ.static_size
            return ret, pop

        stack = [(Path(typ), OffsetExpr(), pop_root)]
        walk(typ, handle)
        return stack[0][1]

    def go_to_end(path: Path) -> WalkCmd:
        return WalkCmd.KEEP_GOING

    def go_to_tok(name: str) -> typing.Callable[[Path], WalkCmd]:
        def ret(path: Path) -> WalkCmd:
            if len(path.elems) == 1 and path.elems[0].name == name:
                return WalkCmd.ABORT
            return WalkCmd.KEEP_GOING

        return ret

    for typ in typs:
        if not (
            isinstance(typ, idl.Message) or typ.name == "stat"
        ):  # SPECIAL (include stat)
            continue
        assert isinstance(typ, idl.Struct)
        ret += "\n"
        ret += ifdef_push(1, c_ver_ifdef(typ.in_versions))
        ret += f"static bool marshal_{typ.name}(struct _marshal_ctx *ctx, {c_typename(typ)} *val) {{\n"

        # Pass 1 - check size
        max_size = max(typ.max_size(v) for v in typ.in_versions)

        if max_size > u32max:  # SPECIAL (9P2000.e)
            ret += get_offset_expr(typ, go_to_end).gen_c(
                "uint64_t", "needed_size", "val->", 1, 0
            )
            ret += "\tif (needed_size > (uint64_t)(ctx->ctx->max_msg_size)) {\n"
        else:
            ret += get_offset_expr(typ, go_to_end).gen_c(
                "uint32_t", "needed_size", "val->", 1, 0
            )
            ret += "\tif (needed_size > ctx->ctx->max_msg_size) {\n"
        if isinstance(typ, idl.Message):  # SPECIAL (disable for stat)
            ret += f'\t\tlib9p_errorf(ctx->ctx, LINUX_ERANGE, "%s message too large to marshal into %s limit (limit=%PRIu32)",\n'
            ret += f'\t\t\t"{typ.name}",\n'
            ret += f'\t\t\tctx->ctx->version ? "negotiated" : "{'client' if typ.msgid % 2 == 0 else 'server'}",\n'
            ret += "\t\t\tctx->ctx->max_msg_size);\n"
        ret += "\t\treturn true;\n"
        ret += "\t}\n"

        # Pass 2 - write data
        ifdef_depth = 1
        stack: list[tuple[Path, bool]] = [(Path(typ), False)]

        def handle(path: Path) -> tuple[WalkCmd, typing.Callable[[], None]]:
            nonlocal ret
            nonlocal ifdef_depth
            nonlocal stack
            stack_len = len(stack)

            def pop() -> None:
                nonlocal ret
                nonlocal ifdef_depth
                nonlocal stack
                nonlocal stack_len
                while len(stack) > stack_len:
                    ret += f"{'\t'*(len(stack)-1)}}}\n"
                    if stack[-1][1]:
                        ifdef_depth -= 1
                        ret += ifdef_pop(ifdef_depth)
                    stack = stack[:-1]

            loopdepth = sum(1 for elem in path.elems if elem.cnt)
            struct = path.elems[-1].typ if path.elems else path.root
            if isinstance(struct, idl.Struct):
                offsets: list[str] = []
                for member in struct.members:
                    if not member.val:
                        continue
                    for tok in member.val.tokens:
                        if not isinstance(tok, idl.ExprSym):
                            continue
                        if tok.name == "end" or tok.name.startswith("&"):
                            if tok.name not in offsets:
                                offsets.append(tok.name)
                for name in offsets:
                    name_prefix = "offsetof_" + "".join(
                        m.name + "_" for m in path.elems
                    )
                    if name == "end":
                        if not path.elems:
                            nonlocal max_size
                            if max_size > u32max:
                                ret += f"{'\t'*len(stack)}uint32_t {name_prefix}end = (uint32_t)needed_size;\n"
                            else:
                                ret += f"{'\t'*len(stack)}uint32_t {name_prefix}end = needed_size;\n"
                            continue
                        recurse: OffsetExprRecursion = go_to_end
                    else:
                        assert name.startswith("&")
                        name = name[1:]
                        recurse = go_to_tok(name)
                    expr = get_offset_expr(struct, recurse)
                    expr_prefix = path.c_str("val->", loopdepth)
                    if not expr_prefix.endswith(">"):
                        expr_prefix += "."
                    ret += expr.gen_c(
                        "uint32_t",
                        name_prefix + name,
                        expr_prefix,
                        len(stack),
                        loopdepth,
                    )
            if path.elems:
                child = path.elems[-1]
                parent = path.elems[-2].typ if len(path.elems) > 1 else path.root
                if child.in_versions < parent.in_versions:
                    ret += ifdef_push(ifdef_depth + 1, c_ver_ifdef(child.in_versions))
                    ifdef_depth += 1
                    ret += f"{'\t'*len(stack)}if ({c_ver_cond(child.in_versions)}) {{\n"
                    stack.append((path, True))
                if child.cnt:
                    cnt_path = path.parent().add(child.cnt)
                    if child.typ.static_size == 1:  # SPECIAL (zerocopy)
                        if path.root.name == "stat":  # SPECIAL (stat)
                            ret += f"{'\t'*len(stack)}MARSHAL_BYTES(ctx, {path.c_str('val->')[:-3]}, {cnt_path.c_str('val->')});\n"
                        else:
                            ret += f"{'\t'*len(stack)}MARSHAL_BYTES_ZEROCOPY(ctx, {path.c_str('val->')[:-3]}, {cnt_path.c_str('val->')});\n"
                        return WalkCmd.KEEP_GOING, pop
                    loopvar = chr(ord("i") + loopdepth - 1)
                    ret += f"{'\t'*len(stack)}for ({c_typename(child.cnt.typ)} {loopvar} = 0; {loopvar} < {cnt_path.c_str('val->')}; {loopvar}++) {{\n"
                    stack.append((path, False))
                if not isinstance(child.typ, idl.Struct):
                    if child.val:

                        def lookup_sym(sym: str) -> str:
                            nonlocal path
                            if sym.startswith("&"):
                                sym = sym[1:]
                            return (
                                "offsetof_"
                                + "".join(m.name + "_" for m in path.elems[:-1])
                                + sym
                            )

                        val = c_expr(child.val, lookup_sym)
                    else:
                        val = path.c_str("val->")
                    if isinstance(child.typ, idl.Bitfield):
                        val += f" & {child.typ.name}_masks[ctx->ctx->version]"
                    ret += f"{'\t'*len(stack)}MARSHAL_U{child.typ.static_size*8}LE(ctx, {val});\n"
            return WalkCmd.KEEP_GOING, pop

        walk(typ, handle)

        ret += "\treturn false;\n"
        ret += "}\n"
    ret += ifdef_pop(0)

    # function tables ##########################################################
    ret += """
/* function tables ************************************************************/
"""

    ret += "\n"
    ret += f"const uint32_t _{idprefix}table_msg_min_size[{c_ver_enum('NUM')}] = {{\n"
    rerror = next(typ for typ in typs if typ.name == "Rerror")
    ret += f"\t[{c_ver_enum('unknown')}] = {rerror.min_size('9P2000')},\n"  # SPECIAL (initialization)
    for ver in sorted(versions):
        ret += ifdef_push(1, c_ver_ifdef({ver}))
        ret += f"\t[{c_ver_enum(ver)}] = {rerror.min_size(ver)},\n"
    ret += ifdef_pop(0)
    ret += "};\n"

    ret += "\n"
    ret += c_macro(
        f"#define _MSG_RECV(typ) [{idprefix.upper()}TYP_##typ/2] = {{\n"
        f"\t\t.basesize  = sizeof(struct {idprefix}msg_##typ),\n"
        f"\t\t.validate  = validate_##typ,\n"
        f"\t\t.unmarshal = (_unmarshal_fn_t)unmarshal_##typ,\n"
        f"\t}}\n"
    )
    ret += c_macro(
        f"#define _MSG_SEND(typ) [{idprefix.upper()}TYP_##typ/2] = {{\n"
        f"\t\t.marshal   = (_marshal_fn_t)marshal_##typ,\n"
        f"\t}}\n"
    )
    ret += "\n"
    ret += msg_table("Tmsg", "recv", f"struct _{idprefix}recv_tentry", (0, 0x100, 2))
    ret += "\n"
    ret += msg_table("Rmsg", "recv", f"struct _{idprefix}recv_tentry", (1, 0x100, 2))
    ret += "\n"
    ret += msg_table("Tmsg", "send", f"struct _{idprefix}send_tentry", (0, 0x100, 2))
    ret += "\n"
    ret += msg_table("Rmsg", "send", f"struct _{idprefix}send_tentry", (1, 0x100, 2))

    ret += f"""
LM_FLATTEN bool _{idprefix}stat_validate(struct _validate_ctx *ctx) {{
\treturn validate_stat(ctx);
}}
LM_FLATTEN void _{idprefix}stat_unmarshal(struct _unmarshal_ctx *ctx, struct {idprefix}stat *out) {{
\tunmarshal_stat(ctx, out);
}}
LM_FLATTEN bool _{idprefix}stat_marshal(struct _marshal_ctx *ctx, struct {idprefix}stat *val) {{
\treturn marshal_stat(ctx, val);
}}
"""

    ############################################################################
    return ret


# Main #########################################################################


if __name__ == "__main__":
    import sys

    if typing.TYPE_CHECKING:

        class ANSIColors:
            MAGENTA = "\x1b[35m"
            RED = "\x1b[31m"
            RESET = "\x1b[0m"

    else:
        from _colorize import ANSIColors  # Present in Python 3.13+

    if len(sys.argv) < 2:
        raise ValueError("requires at least 1 .9p filename")
    parser = idl.Parser()
    for txtname in sys.argv[1:]:
        try:
            parser.parse_file(txtname)
        except SyntaxError as e:
            print(
                f"{ANSIColors.RED}{e.filename}{ANSIColors.RESET}:{ANSIColors.MAGENTA}{e.lineno}{ANSIColors.RESET}: {e.msg}",
                file=sys.stderr,
            )
            assert e.text
            print(f"\t{e.text}", file=sys.stderr)
            print(
                f"\t{ANSIColors.RED}{'~'*len(e.text)}{ANSIColors.RESET}",
                file=sys.stderr,
            )
            sys.exit(2)
    versions, typs = parser.all()
    outdir = os.path.normpath(os.path.join(sys.argv[0], ".."))
    with open(os.path.join(outdir, "include/lib9p/9p.generated.h"), "w") as fh:
        fh.write(gen_h(versions, typs))
    with open(os.path.join(outdir, "9p.generated.c"), "w") as fh:
        fh.write(gen_c(versions, typs))