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#include <Python.h>
static PyObject * hashFunction(PyObject *self, PyObject *args, PyObject *kw)
{
PyStringObject *a;
register int len;
register unsigned char *p;
register unsigned long x;
unsigned long ulSeed;
unsigned long cchSeed;
unsigned long cHashElements;
if (!PyArg_ParseTuple(args, "llOl:hash",
&ulSeed, &cchSeed, &a, &cHashElements))
return NULL;
if (!PyString_Check(a))
{
PyErr_SetString(PyExc_TypeError, "arg 3 needs to be a string");
return NULL;
}
len = a->ob_size;
p = (unsigned char *) a->ob_sval;
x = ulSeed;
while (--len >= 0)
{
/* (1000003 * x) ^ *p++
* translated to handle > 32 bit longs
*/
x = (0xf4243 * x);
x = x & 0xFFFFFFFF;
x = x ^ *p++;
}
x ^= a->ob_size + cchSeed;
if (x == 0xFFFFFFFF)
x = 0xfffffffe;
if (x & 0x80000000)
{
/* Emulate Python 32-bit signed (2's complement)
* modulo operation
*/
x = (~x & 0xFFFFFFFF) + 1;
x %= cHashElements;
if (x != 0)
{
x = x + (~cHashElements & 0xFFFFFFFF) + 1;
x = (~x & 0xFFFFFFFF) + 1;
}
}
else
x %= cHashElements;
return PyInt_FromLong((long)x);
}
static PyObject * calcSeed(PyObject *self, PyObject *args, PyObject *kw)
{
PyStringObject *a;
register int len;
register unsigned char *p;
register unsigned long x;
if (!PyString_Check(args))
{
PyErr_SetString(PyExc_TypeError, "arg 1 expected a string, but didn't get it.");
return NULL;
}
a = (PyStringObject *)args;
len = a->ob_size;
p = (unsigned char *) a->ob_sval;
x = (*p << 7) & 0xFFFFFFFF;
while (--len >= 0)
{
/* (1000003 * x) ^ *p++
* translated to handle > 32 bit longs
*/
x = (0xf4243 * x);
x = x & 0xFFFFFFFF;
x = x ^ *p++;
}
return PyInt_FromLong((long)x);
}
static struct PyMethodDef hashMethods[] = {
{ "calcSeed", calcSeed, 0, NULL },
{ "hash", hashFunction, 0, NULL },
{ NULL, NULL, 0, NULL } /* sentinel */
};
#ifdef _MSC_VER
_declspec(dllexport)
#endif
void initperfhash(void)
{
PyObject *m;
m = Py_InitModule4("perfhash", hashMethods,
NULL, NULL, PYTHON_API_VERSION);
if ( m == NULL )
Py_FatalError("can't initialize module perfhash");
}
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