Mercurial > hg
view mercurial/base85.c @ 7012:78341ea65d16
restructure helptable
When looking up a help topic, the key is now only matched against the
short names for each topic, and not the header. So
hg help 'Environment Variables'
must be replaced with
hg help env
author | Martin Geisler <mg@daimi.au.dk> |
---|---|
date | Tue, 09 Sep 2008 21:32:39 +0200 |
parents | 4bad632913d8 |
children | aecea6934fdd |
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/* 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 void b85prep(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(); }