/* base85 codec  Copyright 2006 Brendan Cully <brendan@kublai.com>  This software may be used and distributed according to the terms of the GNU General Public License, incorporated herein by reference.  Largely based on git's implementation*/ #include <Python.h> static const char b85chars[] = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ"	"abcdefghijklmnopqrstuvwxyz!#$%&()*+-;<=>?@^_`{|}~";static char b85dec[256]; static voidb85prep(void){	int i; 	memset(b85dec, 0, sizeof(b85dec));	for (i = 0; i < sizeof(b85chars); i++)		b85dec[(int)(b85chars[i])] = i + 1;} static PyObject *b85encode(PyObject *self, PyObject *args){	const unsigned char *text;	PyObject *out;	char *dst;	int len, olen, i;	unsigned int acc, val, ch;	int pad = 0; 	if (!PyArg_ParseTuple(args, "s#|i", &text, &len, &pad))		return NULL; 	if (pad)		olen = ((len + 3) / 4 * 5) - 3;	else {		olen = len % 4;		if (olen)			olen++;		olen += len / 4 * 5;	}	if (!(out = PyString_FromStringAndSize(NULL, olen + 3)))		return NULL; 	dst = PyString_AS_STRING(out); 	while (len) {		acc = 0;		for (i = 24; i >= 0; i -= 8) {			ch = *text++;			acc |= ch << i;			if (--len == 0)				break;		}		for (i = 4; i >= 0; i--) {			val = acc % 85;			acc /= 85;			dst[i] = b85chars[val];		}		dst += 5;	} 	if (!pad)		_PyString_Resize(&out, olen); 	return out;} static PyObject *b85decode(PyObject *self, PyObject *args){	PyObject *out;	const char *text;	char *dst;	int len, i, j, olen, c, cap;	unsigned int acc; 	if (!PyArg_ParseTuple(args, "s#", &text, &len))		return NULL; 	olen = len / 5 * 4;	i = len % 5;	if (i)		olen += i - 1;	if (!(out = PyString_FromStringAndSize(NULL, olen)))		return NULL; 	dst = PyString_AS_STRING(out); 	i = 0;	while (i < len)	{		acc = 0;		cap = len - i - 1;		if (cap > 4)			cap = 4;		for (j = 0; j < cap; i++, j++)		{			c = b85dec[(int)*text++] - 1;			if (c < 0)				return PyErr_Format(PyExc_ValueError, "Bad base85 character at position %d", i);			acc = acc * 85 + c;		}		if (i++ < len)		{			c = b85dec[(int)*text++] - 1;			if (c < 0)				return PyErr_Format(PyExc_ValueError, "Bad base85 character at position %d", i);			/* overflow detection: 0xffffffff == "|NsC0",			 * "|NsC" == 0x03030303 */			if (acc > 0x03030303 || (acc *= 85) > 0xffffffff - c)				return PyErr_Format(PyExc_ValueError, "Bad base85 sequence at position %d", i);			acc += c;		} 		cap = olen < 4 ? olen : 4;		olen -= cap;		for (j = 0; j < 4 - cap; j++)			acc *= 85;		if (cap && cap < 4)			acc += 0xffffff >> (cap - 1) * 8;		for (j = 0; j < cap; j++)		{			acc = (acc << 8) | (acc >> 24);			*dst++ = acc;		}	} 	return out;} static char base85_doc[] = "Base85 Data Encoding"; static PyMethodDef methods[] = {	{"b85encode", b85encode, METH_VARARGS,	 "Encode text in base85.\n\n"	 "If the second parameter is true, pad the result to a multiple of "	 "five characters.\n"},	{"b85decode", b85decode, METH_VARARGS, "Decode base85 text.\n"},	{NULL, NULL}}; PyMODINIT_FUNC initbase85(void){	Py_InitModule3("base85", methods, base85_doc); 	b85prep();}