diff options
| -rw-r--r-- | miasm2/core/bin_stream.py | 35 |
1 files changed, 34 insertions, 1 deletions
diff --git a/miasm2/core/bin_stream.py b/miasm2/core/bin_stream.py index 680b87ab..f716d902 100644 --- a/miasm2/core/bin_stream.py +++ b/miasm2/core/bin_stream.py @@ -16,10 +16,17 @@ # 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. # import math +from miasm2.core.utils import BoundedDict class bin_stream(object): + # Cache must be initialized by entering atomic mode + _cache = None + CACHE_SIZE = 10000 + # By default, no atomic mode + _atomic_mode = False + def __init__(self, *args, **kargs): pass @@ -29,9 +36,35 @@ class bin_stream(object): def hexdump(self, offset, l): return - def getbytes(self, start, l=1): + def enter_atomic_mode(self): + """Enter atomic mode. In this mode, read may be cached""" + self._atomic_mode = True + self._cache = BoundedDict(self.CACHE_SIZE) + + def leave_atomic_mode(self): + """Leave atomic mode""" + self._atomic_mode = False + self._cache = None + + def _getbytes(self, start, length): return self.bin[start:start + l] + def getbytes(self, start, l=1): + """Return the bytes from the bit stream + @start: starting offset (in byte) + @l: (optional) number of bytes to read + + Wrapper on _getbytes, with atomic mode handling. + """ + if self._atomic_mode: + val = self._cache.get((start,l), None) + if val is None: + val = self._getbytes(start, l) + self._cache[(start,l)] = val + else: + val = self._getbytes(start, l) + return val + def getbits(self, start, n): """Return the bits from the bit stream @start: the offset in bits |