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

   1 # -*-pyrex-*-
   2 #
   3 # $Id$
   4 #
   5 # Universal hashing interface
   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/unihash.h':
  29   ctypedef int uint32
  30   ctypedef struct unihash_info:
  31     pass
  32   void unihash_setkey(unihash_info *i, uint32 k)
  33   uint32 UNIHASH_INIT(unihash_info *i)
  34   uint32 unihash_hash(unihash_info *i, uint32 a, void *p, int sz)
  35   unihash_info unihash_global
  36
  37 cdef extern from 'limits.h':
  38   enum:
  39     LONG_MAX
  40
  41 cdef extern from 'Python.h':
  42   int PyObject_AsReadBuffer(obj, void **buf, int *len) except -1
  43   PyInt_FromLong(long i)
  44   PyLong_FromUnsignedLong(unsigned long i)
  45
  46 cdef _u32(uint32 x):
  47   if x < LONG_MAX:
  48     return PyInt_FromLong(x)
  49   else:
  50     return PyLong_FromUnsignedLong(x)
  51
  52 def setglobalkey(uint32 k):
  53   unihash_setkey(&unihash_global, k)
  54
  55 cdef class Key:
  56   cdef unihash_info _i
  57   cdef uint32 _k
  58   def __new__(me, uint32 k):
  59     unihash_setkey(&me._i, k)
  60     me._k = k
  61   property k:
  62     def __get__(me):
  63       return _u32(me._k)
  64
  65 cdef class Unihash:
  66   cdef uint32 _a
  67   cdef readonly Key key
  68   cdef unihash_info *_i
  69   def __new__(me, key = None):
  70     cdef Key k
  71     me.key = key
  72     if key is None:
  73       me._i = &unihash_global
  74     else:
  75       k = key
  76       me._i = &k._i
  77     me._a = UNIHASH_INIT(me._i)
  78   def chunk(me, data):
  79     cdef void *p
  80     cdef int n
  81     PyObject_AsReadBuffer(data, &p, &n)
  82     me._a = unihash_hash(me._i, me._a, p, n)
  83   def done(me):
  84     return _u32(me._a)
  85
  86 #----- That's all, folks ----------------------------------------------------