/*
 * C implementation of the pyutil xor module.
 *
 * 
 * Copyright (c) 2002 Faried Nawaz
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software to deal in this software without restriction, including
 * without limitation the rights to use, copy, modify, merge, publish,
 * distribute, sublicense, and/or sell copies of this software, and to permit
 * persons to whom this software is furnished to do so, subject to the following
 * conditions:
 *
 * The above copyright notice and this permission notice shall be included in all
 * copies or substantial portions of this software.
 *
 * THIS SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THIS SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THIS SOFTWARE.
 *
 * Optimized and patched by Zooko, 2002-07-18
 */

#include <assert.h>

#include <Python.h>

#define C_XOR_VERSION  "1.1"

static PyObject *
c_xor_xor(PyObject *self, PyObject *args) {
	const unsigned char *str1, *str2;
	int len_str1, len_str2;
	PyObject * newstr;
	unsigned char *bytep;
	const unsigned char *endp;

	if (!PyArg_ParseTuple(args, "s#s#", &str1, &len_str1, &str2, &len_str2))
		return NULL;

	if (len_str1 != len_str2) {
		/* XXX It would be nicer to raise an instance of type AssertionError here so that the behavior would be the same as xor.py_xor().   But people should not be catching assertion errors anyway. */
		PyErr_SetString(PyExc_ValueError, "passed strings must be of the same length.");
		return NULL;
	}

	/* Calling PyString_FromStringAndSize with NULL first argument is a special call that asks PyString_FromStringAndSize to allocate the buffer for us, and appended the null terminating byte. */
	newstr = PyString_FromStringAndSize(NULL, len_str1);
	if (newstr == NULL)
		return NULL; /* the Python/C API is that the function which returned NULL (PyString_FromStringAndSize) has already set the global PyErr value for us, so we just release any refcounts and return NULL. */

	bytep = PyString_AS_STRING(newstr);
	assert (bytep != NULL);
	endp = PyString_AS_STRING(newstr) + len_str1;

	while (bytep < endp)
		*bytep++ = *str1++ ^ *str2++;

	return newstr;
}

static PyMethodDef XorMethods[] = {
	{"xor", c_xor_xor, METH_VARARGS, "Exclusive-Or on two strings."},
	{NULL, NULL, 0, NULL}
};


void
initc_xor(void) {
	Py_InitModule("c_xor", XorMethods);
}

int main(int argc, char **argv) {
	Py_SetProgramName(argv[0]);
	Py_Initialize();
	initc_xor();
	return 0;
}