124 lines
3.9 KiB
Python
124 lines
3.9 KiB
Python
"""LLDB summaries for Rust's `fixed` crate.
|
|
|
|
Load this file from LLDB with:
|
|
|
|
command script import /path/to/shinespark/tools/lldb_fixed.py
|
|
|
|
The implementation does not use floating-point arithmetic, so displayed values
|
|
are exact even for FixedI128/FixedU128 values.
|
|
"""
|
|
|
|
import re
|
|
|
|
try:
|
|
import lldb
|
|
except ImportError:
|
|
# Keep the pure parsing and formatting helpers testable without LLDB.
|
|
lldb = None
|
|
|
|
|
|
_FIXED_TYPE_RE = re.compile(r"(?:^|::)Fixed([IU])(8|16|32|64|128)<(.+)>$")
|
|
_DIRECT_TYPENUM_RE = re.compile(r"(?:^|::)U(\d+)$")
|
|
_TYPENUM_BIT_RE = re.compile(r"(?:^|::)B([01])(?=\s*[,>])")
|
|
|
|
|
|
def parse_fixed_type(type_name):
|
|
"""Return (signed, storage_bits, fractional_bits), or None."""
|
|
if not type_name:
|
|
return None
|
|
|
|
match = _FIXED_TYPE_RE.search(type_name.replace(" ", ""))
|
|
if match is None:
|
|
return None
|
|
|
|
signed = match.group(1) == "I"
|
|
storage_bits = int(match.group(2))
|
|
fractional_type = match.group(3)
|
|
|
|
direct = _DIRECT_TYPENUM_RE.search(fractional_type)
|
|
if direct is not None:
|
|
fractional_bits = int(direct.group(1))
|
|
else:
|
|
# typenum represents UInt<N, B> as a binary tree. Its textual Rust
|
|
# type lists the bits from most significant to least significant.
|
|
digits = _TYPENUM_BIT_RE.findall(fractional_type)
|
|
if not digits:
|
|
return None
|
|
fractional_bits = int("".join(digits), 2)
|
|
|
|
if fractional_bits > storage_bits:
|
|
return None
|
|
return signed, storage_bits, fractional_bits
|
|
|
|
|
|
def normalize_bits(raw_bits, signed, storage_bits):
|
|
"""Interpret a possibly unsigned LLDB integer using the fixed type's width."""
|
|
mask = (1 << storage_bits) - 1
|
|
raw_bits &= mask
|
|
if signed and raw_bits >= 1 << (storage_bits - 1):
|
|
raw_bits -= 1 << storage_bits
|
|
return raw_bits
|
|
|
|
|
|
def format_fixed(raw_bits, fractional_bits):
|
|
"""Format a scaled integer exactly as a decimal string."""
|
|
if fractional_bits == 0:
|
|
return str(raw_bits)
|
|
|
|
negative = raw_bits < 0
|
|
magnitude = -raw_bits if negative else raw_bits
|
|
whole = magnitude >> fractional_bits
|
|
remainder = magnitude & ((1 << fractional_bits) - 1)
|
|
|
|
if remainder == 0:
|
|
result = str(whole)
|
|
else:
|
|
# remainder / 2^n == (remainder * 5^n) / 10^n, which gives a finite,
|
|
# exact decimal representation without converting through a float.
|
|
decimal = str(remainder * 5**fractional_bits).zfill(fractional_bits)
|
|
result = f"{whole}.{decimal.rstrip('0')}"
|
|
|
|
return f"-{result}" if negative else result
|
|
|
|
|
|
def _parse_lldb_integer(value):
|
|
text = value.GetValue()
|
|
if text is not None:
|
|
try:
|
|
return int(text, 0)
|
|
except ValueError:
|
|
pass
|
|
|
|
# GetValueAsUnsigned is also useful on LLDB versions that do not render
|
|
# primitive values through GetValue. It is sufficient for all <= 64-bit
|
|
# fixed types; current LLDB versions render i128/u128 through GetValue.
|
|
return value.GetValueAsUnsigned()
|
|
|
|
|
|
def fixed_summary(value, _internal_dict):
|
|
layout = parse_fixed_type(value.GetTypeName())
|
|
if layout is None:
|
|
return None
|
|
|
|
signed, storage_bits, fractional_bits = layout
|
|
bits = value.GetChildMemberWithName("bits")
|
|
if not bits.IsValid():
|
|
return None
|
|
|
|
raw_bits = _parse_lldb_integer(bits)
|
|
raw_bits = normalize_bits(raw_bits, signed, storage_bits)
|
|
return format_fixed(raw_bits, fractional_bits)
|
|
|
|
|
|
def __lldb_init_module(debugger, _internal_dict):
|
|
# LLDB's type-name regex sees the concrete fixed type rather than project
|
|
# aliases such as FGi32 and FGWide.
|
|
debugger.HandleCommand(
|
|
"type summary add --python-function lldb_fixed.fixed_summary "
|
|
"--category Shinespark --regex "
|
|
"'^fixed::Fixed(I|U)(8|16|32|64|128)<.+>$'"
|
|
)
|
|
# A dedicated category makes the formatter work even when CodeLLDB has not
|
|
# enabled rustc's standard `Rust` formatter category yet.
|
|
debugger.HandleCommand("type category enable Shinespark")
|