mdw@git.distorted.org.uk Git - mLib-python/blob - crc32.pyx

   1 # -*-pyrex-*-
   2 #
   3 # $Id$
   4 #
   5 # Cyclic redundancy checker
   6 #
   7 # (c) 2005 Straylight/Edgeware
   8 #
   9
  10 #----- Licensing notice -----------------------------------------------------
  11 #
  12 # This file is part of the Python interface to mLib.
  13 #
  14 # mLib/Python is free software; you can redistribute it and/or modify
  15 # it under the terms of the GNU General Public License as published by
  16 # the Free Software Foundation; either version 2 of the License, or
  17 # (at your option) any later version.
  18 #
  19 # mLib/Python is distributed in the hope that it will be useful,
  20 # but WITHOUT ANY WARRANTY; without even the implied warranty of
  21 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  22 # GNU General Public License for more details.
  23 #
  24 # You should have received a copy of the GNU General Public License
  25 # along with mLib/Python; if not, write to the Free Software Foundation,
  26 # Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  27
  28 cdef extern from 'mLib/crc32.h':
  29   ctypedef int uint32
  30   uint32 c_crc32 "crc32" (uint32 a, void *p, int sz)
  31
  32 cdef extern from 'limits.h':
  33   enum:
  34     LONG_MAX
  35
  36 cdef extern from 'Python.h':
  37   int PyObject_AsReadBuffer(obj, void **buf, int *len) except -1
  38   PyInt_FromLong(long i)
  39   PyLong_FromUnsignedLong(unsigned long i)
  40
  41 cdef _u32(uint32 x):
  42   if x < LONG_MAX:
  43     return PyInt_FromLong(x)
  44   else:
  45     return PyLong_FromUnsignedLong(x)
  46
  47 cdef class CRC32:
  48   cdef uint32 _a
  49   def __new__(me, *hunoz, **hukairz):
  50     me._a = 0
  51   def __init__(me):
  52     pass
  53   def chunk(me, data):
  54     cdef void *p
  55     cdef int n
  56     PyObject_AsReadBuffer(data, &p, &n)
  57     me._a = c_crc32(me._a, p, n)
  58     return me
  59   def done(me):
  60     return _u32(me._a)
  61
  62 def crc32(data):
  63   cdef void *p
  64   cdef int n
  65   cdef uint32 c
  66   PyObject_AsReadBuffer(data, &p, &n)
  67   c = c_crc32(0, p, n)
  68   return _u32(c)
  69
  70 #----- That's all, folks ----------------------------------------------------