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Refactor encoding of bit field

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This commit is contained in:
Alexis Engelke
2019-05-05 12:26:20 +02:00
parent dff78c5a86
commit 899278600b
1 changed files with 7 additions and 7 deletions
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14
parseinstrs.py
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@@ -16,11 +16,12 @@ def bitstruct(name, fields):
def __init__(self, **kwargs): def __init__(self, **kwargs):
for name in names: for name in names:
setattr(self, name, kwargs.get(name, 0)) setattr(self, name, kwargs.get(name, 0))
def _encode(self): def _encode(self, length):
return sum((getattr(self, name) & ((1 << size) - 1)) << offset enc = 0
for name, size, offset in zip(names, sizes, offsets)) for name, size, offset in zip(names, sizes, offsets):
enc += (getattr(self, name) & ((1 << size) - 1)) << offset
return enc.to_bytes(length, "little")
__class.__name__ = name __class.__name__ = name
__class._encode_size = offsets[-1]
return __class return __class
InstrFlags = bitstruct("InstrFlags", [ InstrFlags = bitstruct("InstrFlags", [
@@ -40,7 +41,6 @@ InstrFlags = bitstruct("InstrFlags", [
"lock:1", "lock:1",
"vsib:1", "vsib:1",
]) ])
assert InstrFlags._encode_size <= 32
ENCODINGS = { ENCODINGS = {
"NP": InstrFlags(), "NP": InstrFlags(),
@@ -119,9 +119,9 @@ class InstrDesc(namedtuple("InstrDesc", "mnemonic,flags,encoding")):
if "LOCK" in desc[6:]: flags.lock = 1 if "LOCK" in desc[6:]: flags.lock = 1
if "VSIB" in desc[6:]: flags.vsib = 1 if "VSIB" in desc[6:]: flags.vsib = 1
return cls(desc[5], frozenset(desc[6:]), flags._encode()) return cls(desc[5], frozenset(desc[6:]), flags._encode(6))
def encode(self, mnemonics_lut): def encode(self, mnemonics_lut):
return struct.pack("<HL", mnemonics_lut[self.mnemonic], self.encoding) return struct.pack("<H", mnemonics_lut[self.mnemonic]) + self.encoding
class EntryKind(Enum): class EntryKind(Enum):
NONE = 0 NONE = 0