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# lib9p/protogen/c_unmarshal.py - Generate C unmarshal functions
#
# Copyright (C) 2024-2025 Luke T. Shumaker <lukeshu@lukeshu.com>
# SPDX-License-Identifier: AGPL-3.0-or-later
import typing
import idl
from . import c9util, cutil, idlutil
# 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".
# pylint: disable=unused-variable
__all__ = ["gen_c_unmarshal"]
def gen_c_unmarshal(versions: set[str], typs: list[idl.UserType]) -> str:
ret = """
/* unmarshal_* ****************************************************************/
"""
ret += cutil.macro(
"#define UNMARSHAL_BYTES(ctx, data_lvalue, len)\n"
"\tdata_lvalue = (char *)&ctx->net_bytes[ctx->net_offset];\n"
"\tctx->net_offset += len;\n"
)
ret += cutil.macro(
"#define UNMARSHAL_U8LE(ctx, val_lvalue)\n"
"\tval_lvalue = ctx->net_bytes[ctx->net_offset];\n"
"\tctx->net_offset += 1;\n"
)
ret += cutil.macro(
"#define UNMARSHAL_U16LE(ctx, val_lvalue)\n"
"\tval_lvalue = uint16le_decode(&ctx->net_bytes[ctx->net_offset]);\n"
"\tctx->net_offset += 2;\n"
)
ret += cutil.macro(
"#define UNMARSHAL_U32LE(ctx, val_lvalue)\n"
"\tval_lvalue = uint32le_decode(&ctx->net_bytes[ctx->net_offset]);\n"
"\tctx->net_offset += 4;\n"
)
ret += cutil.macro(
"#define UNMARSHAL_U64LE(ctx, val_lvalue)\n"
"\tval_lvalue = uint64le_decode(&ctx->net_bytes[ctx->net_offset]);\n"
"\tctx->net_offset += 8;\n"
)
class IndentLevel(typing.NamedTuple):
ifdef: bool # whether this is both `{` and `#if`, or just `{`
indent_stack: list[IndentLevel]
def ifdef_lvl() -> int:
return sum(1 if lvl.ifdef else 0 for lvl in indent_stack)
def indent_lvl() -> int:
return len(indent_stack)
def handle(
path: idlutil.Path,
) -> tuple[idlutil.WalkCmd, typing.Callable[[], None]]:
nonlocal ret
nonlocal indent_stack
indent_stack_len = len(indent_stack)
def pop() -> None:
nonlocal ret
nonlocal indent_stack
nonlocal indent_stack_len
while len(indent_stack) > indent_stack_len:
if len(indent_stack) == indent_stack_len + 1 and indent_stack[-1].ifdef:
break
ret += f"{'\t'*(indent_lvl()-1)}}}\n"
if indent_stack.pop().ifdef:
ret += cutil.ifdef_pop(ifdef_lvl())
if not path.elems:
return idlutil.WalkCmd.KEEP_GOING, pop
child = path.elems[-1]
parent = path.elems[-2].typ if len(path.elems) > 1 else path.root
if child.in_versions < parent.in_versions:
if line := cutil.ifdef_push(
ifdef_lvl() + 1, c9util.ver_ifdef(child.in_versions)
):
ret += line
ret += (
f"{'\t'*indent_lvl()}if ({c9util.ver_cond(child.in_versions)}) {{\n"
)
indent_stack.append(IndentLevel(ifdef=True))
if child.cnt:
cnt_path = path.parent().add(child.cnt)
if child.typ.static_size == 1: # SPECIAL (zerocopy)
ret += f"{'\t'*indent_lvl()}UNMARSHAL_BYTES(ctx, {path.c_str('out->')[:-3]}, {cnt_path.c_str('out->')});\n"
return idlutil.WalkCmd.KEEP_GOING, pop
ret += f"{'\t'*indent_lvl()}{path.c_str('out->')[:-3]} = ctx->extra;\n"
ret += f"{'\t'*indent_lvl()}ctx->extra += sizeof({path.c_str('out->')[:-3]}[0]) * {cnt_path.c_str('out->')};\n"
loopdepth = sum(1 for elem in path.elems if elem.cnt)
loopvar = chr(ord("i") + loopdepth - 1)
ret += f"{'\t'*indent_lvl()}for ({c9util.typename(child.cnt.typ)} {loopvar} = 0; {loopvar} < {cnt_path.c_str('out->')}; {loopvar}++) {{\n"
indent_stack.append(IndentLevel(ifdef=False))
if not isinstance(child.typ, idl.Struct):
if child.val:
ret += (
f"{'\t'*indent_lvl()}ctx->net_offset += {child.typ.static_size};\n"
)
else:
ret += f"{'\t'*indent_lvl()}UNMARSHAL_U{child.typ.static_size*8}LE(ctx, {path.c_str('out->')});\n"
return idlutil.WalkCmd.KEEP_GOING, pop
for typ in typs:
if not (
isinstance(typ, idl.Message) or typ.typname == "stat"
): # SPECIAL (include stat)
continue
assert isinstance(typ, idl.Struct)
ret += "\n"
ret += cutil.ifdef_push(1, c9util.ver_ifdef(typ.in_versions))
ret += f"static void unmarshal_{typ.typname}(struct _unmarshal_ctx *ctx, {c9util.typename(typ)} *out) {{\n"
indent_stack = [IndentLevel(ifdef=True)]
idlutil.walk(typ, handle)
while len(indent_stack) > 0:
ret += f"{'\t'*(indent_lvl()-1)}}}\n"
if indent_stack.pop().ifdef and indent_stack:
ret += cutil.ifdef_pop(ifdef_lvl())
ret += cutil.ifdef_pop(0)
return ret
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