pyx/font/_t1code.c

   1 /*  t1code.c: Copyright 2005 Jörg Lehmann
   2  *  This program is distributed in the hope that it will be useful,
   3  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
   4  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   5  *  GNU General Public License for more details.
   6  *
   7  *  You should have received a copy of the GNU General Public License
   8  *  along with this program; if not, write to the Free Software
   9  *  Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307,
  10  *  USA.
  11  */
  12
  13 #include <Python.h>
  14 #include <stdlib.h>
  15 #include <stdint.h>
  16
  17 #define C1 52845
  18 #define C2 22719
  19
  20 /*
  21 def decoder(code, r, n):
  22     c1 = 52845
  23     c2 = 22719
  24     data = array.array("B")
  25     for x in array.array("B", code):
  26         data.append(x ^ (r >> 8))
  27         r = ((x + r) * c1 + c2) & 0xffff
  28     return data.tostring()[n:]
  29
  30 */
  31
  32 static PyObject *py_decoder(PyObject *self, PyObject *args)
  33 {
  34     unsigned char *code;
  35     int lcode, n;
  36     uint16_t r;
  37
  38     /* XXX: should we use U (unsigned int) for argument r */
  39     if (PyArg_ParseTuple(args, "s#ii", (char **) &code, &lcode, (int *) &r, &n)) {
  40       unsigned char *data;
  41       int i;
  42       unsigned char x;
  43       PyObject *result;
  44
  45       if (! (data = (unsigned char *) malloc(lcode)) )
  46           return NULL;
  47
  48       for (i=0; i<lcode; i++) {
  49         x = code[i];
  50         data[i] = x ^ ( r >> 8);
  51         r = (x + r) * C1 + C2;
  52       }
  53
  54       /* convert result to string stripping first n chars */
  55       result = PyString_FromStringAndSize((const char *)data + n, lcode - n);
  56       free(data);
  57       return result;
  58     }
  59     else return NULL;
  60
  61 }
  62
  63 /*
  64 def encoder(data, r, random):
  65     c1 = 52845
  66     c2 = 22719
  67     code = array.array("B")
  68     for x in array.array("B", random+data):
  69         code.append(x ^ (r >> 8))
  70         r = ((code[-1] + r) * c1 + c2) & 0xffff;
  71     return code.tostring()
  72 */
  73
  74 static PyObject *py_encoder(PyObject *self, PyObject *args)
  75 {
  76     unsigned char *data;
  77     unsigned char *random;
  78     int ldata, lrandom;
  79     uint16_t r;
  80
  81     /* XXX: should we use U (unsigned int) for argument r */
  82     if (PyArg_ParseTuple(args, "s#is#", (char **) &data, &ldata, (int *) &r, (char **) &random, &lrandom)) {
  83       unsigned char *code;
  84       int i;
  85       PyObject *result;
  86
  87       if (! (code = (unsigned char *) malloc(ldata + lrandom)) )
  88           return NULL;
  89
  90       for (i=0; i<lrandom; i++) {
  91         code[i] = random[i] ^ ( r >> 8);
  92         r = (code[i] + r) * C1 + C2;
  93       }
  94
  95       for (i=0; i<ldata; i++) {
  96         code[i+lrandom] = data[i] ^ ( r >> 8);
  97         r = (code[i+lrandom] + r) * C1 + C2;
  98       }
  99
 100       result = PyString_FromStringAndSize((const char *)code, ldata + lrandom);
 101       free(code);
 102       return result;
 103     }
 104     else return NULL;
 105
 106 }
 107
 108
 109
 110 /* exported methods */
 111
 112 static PyMethodDef t1code_methods[] = {
 113     {"decoder", py_decoder,  METH_VARARGS},
 114     {"encoder", py_encoder,  METH_VARARGS},
 115     {NULL, NULL}
 116 };
 117
 118 void init_t1code(void) {
 119     (void) Py_InitModule("_t1code", t1code_methods);
 120 }