1 files changed, 84 insertions, 0 deletions
diff --git a/lib9p/protogen/cutil.py b/lib9p/protogen/cutil.py
new file mode 100644
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+++ b/lib9p/protogen/cutil.py
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+# lib9p/protogen/cutil.py - Utilities for generating C code
+#
+# Copyright (C) 2024-2025  Luke T. Shumaker <lukeshu@lukeshu.com>
+# SPDX-License-Identifier: AGPL-3.0-or-later
+
+# pylint: disable=unused-variable
+__all__ = [
+    "UINT32_MAX",
+    "UINT64_MAX",
+    "macro",
+    "ifdef_init",
+    "ifdef_push",
+    "ifdef_pop",
+    "ifdef_leaf_is_noop",
+]
+
+UINT32_MAX = (1 << 32) - 1
+UINT64_MAX = (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 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"
+
+
+_ifdef_stack: list[str | None] = []
+
+
+def ifdef_init() -> None:
+    global _ifdef_stack
+    _ifdef_stack = []
+
+
+def ifdef_push(n: int, _newval: str) -> str:
+    # Grow the stack as needed
+    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
+
+
+def ifdef_leaf_is_noop() -> bool:
+    return not _ifdef_stack[-1]