Mercurial > hg
annotate mercurial/base85.c @ 6736:369ddc9c0339
lookup: optimize '.'
Remove error messages as behavior is documented in hg help revs
author | Matt Mackall <mpm@selenic.com> |
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date | Wed, 25 Jun 2008 17:33:34 -0500 |
parents | 4bad632913d8 |
children | aecea6934fdd |
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3283 | 1 /* |
2 base85 codec | |
3 | |
4 Copyright 2006 Brendan Cully <brendan@kublai.com> | |
5 | |
6 This software may be used and distributed according to the terms of | |
7 the GNU General Public License, incorporated herein by reference. | |
8 | |
9 Largely based on git's implementation | |
10 */ | |
11 | |
12 #include <Python.h> | |
13 | |
14 static const char b85chars[] = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ" | |
15 "abcdefghijklmnopqrstuvwxyz!#$%&()*+-;<=>?@^_`{|}~"; | |
16 static char b85dec[256]; | |
17 | |
18 static void | |
19 b85prep(void) | |
20 { | |
21 int i; | |
22 | |
23 memset(b85dec, 0, sizeof(b85dec)); | |
24 for (i = 0; i < sizeof(b85chars); i++) | |
25 b85dec[(int)(b85chars[i])] = i + 1; | |
26 } | |
27 | |
28 static PyObject * | |
29 b85encode(PyObject *self, PyObject *args) | |
30 { | |
31 const unsigned char *text; | |
32 PyObject *out; | |
33 char *dst; | |
34 int len, olen, i; | |
35 unsigned int acc, val, ch; | |
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36 int pad = 0; |
3283 | 37 |
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38 if (!PyArg_ParseTuple(args, "s#|i", &text, &len, &pad)) |
3283 | 39 return NULL; |
40 | |
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41 if (pad) |
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42 olen = ((len + 3) / 4 * 5) - 3; |
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43 else { |
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44 olen = len % 4; |
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45 if (olen) |
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46 olen++; |
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47 olen += len / 4 * 5; |
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48 } |
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49 if (!(out = PyString_FromStringAndSize(NULL, olen + 3))) |
3283 | 50 return NULL; |
51 | |
52 dst = PyString_AS_STRING(out); | |
53 | |
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54 while (len) { |
3283 | 55 acc = 0; |
56 for (i = 24; i >= 0; i -= 8) { | |
57 ch = *text++; | |
58 acc |= ch << i; | |
59 if (--len == 0) | |
60 break; | |
61 } | |
62 for (i = 4; i >= 0; i--) { | |
63 val = acc % 85; | |
64 acc /= 85; | |
65 dst[i] = b85chars[val]; | |
66 } | |
67 dst += 5; | |
68 } | |
69 | |
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70 if (!pad) |
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71 _PyString_Resize(&out, olen); |
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72 |
3283 | 73 return out; |
74 } | |
75 | |
76 static PyObject * | |
77 b85decode(PyObject *self, PyObject *args) | |
78 { | |
79 PyObject *out; | |
80 const char *text; | |
81 char *dst; | |
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82 int len, i, j, olen, c, cap; |
3283 | 83 unsigned int acc; |
84 | |
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85 if (!PyArg_ParseTuple(args, "s#", &text, &len)) |
3283 | 86 return NULL; |
87 | |
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88 olen = len / 5 * 4; |
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89 i = len % 5; |
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90 if (i) |
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91 olen += i - 1; |
3283 | 92 if (!(out = PyString_FromStringAndSize(NULL, olen))) |
93 return NULL; | |
94 | |
95 dst = PyString_AS_STRING(out); | |
96 | |
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97 i = 0; |
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98 while (i < len) |
3283 | 99 { |
100 acc = 0; | |
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101 cap = len - i - 1; |
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102 if (cap > 4) |
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103 cap = 4; |
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104 for (j = 0; j < cap; i++, j++) |
3283 | 105 { |
106 c = b85dec[(int)*text++] - 1; | |
107 if (c < 0) | |
108 return PyErr_Format(PyExc_ValueError, "Bad base85 character at position %d", i); | |
109 acc = acc * 85 + c; | |
110 } | |
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111 if (i++ < len) |
3283 | 112 { |
113 c = b85dec[(int)*text++] - 1; | |
114 if (c < 0) | |
115 return PyErr_Format(PyExc_ValueError, "Bad base85 character at position %d", i); | |
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116 /* overflow detection: 0xffffffff == "|NsC0", |
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117 * "|NsC" == 0x03030303 */ |
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118 if (acc > 0x03030303 || (acc *= 85) > 0xffffffff - c) |
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119 return PyErr_Format(PyExc_ValueError, "Bad base85 sequence at position %d", i); |
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120 acc += c; |
3283 | 121 } |
122 | |
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123 cap = olen < 4 ? olen : 4; |
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124 olen -= cap; |
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125 for (j = 0; j < 4 - cap; j++) |
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126 acc *= 85; |
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127 if (cap && cap < 4) |
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128 acc += 0xffffff >> (cap - 1) * 8; |
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129 for (j = 0; j < cap; j++) |
3283 | 130 { |
131 acc = (acc << 8) | (acc >> 24); | |
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132 *dst++ = acc; |
3283 | 133 } |
134 } | |
135 | |
136 return out; | |
137 } | |
138 | |
139 static char base85_doc[] = "Base85 Data Encoding"; | |
140 | |
141 static PyMethodDef methods[] = { | |
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142 {"b85encode", b85encode, METH_VARARGS, |
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143 "Encode text in base85.\n\n" |
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144 "If the second parameter is true, pad the result to a multiple of " |
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145 "five characters.\n"}, |
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146 {"b85decode", b85decode, METH_VARARGS, "Decode base85 text.\n"}, |
3283 | 147 {NULL, NULL} |
148 }; | |
149 | |
150 PyMODINIT_FUNC initbase85(void) | |
151 { | |
152 Py_InitModule3("base85", methods, base85_doc); | |
153 | |
154 b85prep(); | |
155 } |