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
  16 #define C1 52845
  17 #define C2 22719
  18
  19 /*
  20 def decoder(code, r, n):
  21     c1 = 52845
  22     c2 = 22719
  23     data = array.array("B")
  24     for x in array.array("B", code):
  25         data.append(x ^ (r >> 8))
  26         r = ((x + r) * c1 + c2) & 0xffff
  27     return data.tostring()[n:]
  28
  29 */
  30
  31 static PyObject *py_decoder(PyObject *self, PyObject *args)
  32 {
  33     unsigned char *code;
  34     int lcode, r, n;
  35
  36     if (PyArg_ParseTuple(args, "s#ii", (char **) &code, &lcode, &r, &n)) {
  37       unsigned char *data;
  38       int i;
  39       unsigned char x;
  40       PyObject *result;
  41
  42       if (! (data = (unsigned char *) malloc(lcode)) )
  43           return NULL;
  44
  45       for (i=0; i<lcode; i++) {
  46         x = code[i];
  47         data[i] = x ^ ( r >> 8);
  48         r = ((x + r) * C1 + C2) & 0xFFFF;
  49       }
  50
  51       /* convert result to string stripping first n chars */
  52       result = PyString_FromStringAndSize((const char *)data + n, lcode - n);
  53       free(data);
  54       return result;
  55     }
  56     else return NULL;
  57
  58 }
  59
  60 /*
  61 def encoder(data, r, random):
  62     c1 = 52845
  63     c2 = 22719
  64     code = array.array("B")
  65     for x in array.array("B", random+data):
  66         code.append(x ^ (r >> 8))
  67         r = ((code[-1] + r) * c1 + c2) & 0xffff;
  68     return code.tostring()
  69 */
  70
  71 static PyObject *py_encoder(PyObject *self, PyObject *args)
  72 {
  73     unsigned char *data;
  74     unsigned char *random;
  75     int ldata, lrandom, r;
  76
  77     if (PyArg_ParseTuple(args, "s#is#", (char **) &data, &ldata, &r, (char **) &random, &lrandom)) {
  78       unsigned char *code;
  79       int i;
  80       PyObject *result;
  81
  82       if (! (code = (unsigned char *) malloc(ldata + lrandom)) )
  83           return NULL;
  84
  85       for (i=0; i<lrandom; i++) {
  86         code[i] = random[i] ^ ( r >> 8);
  87         r = ((code[i] + r) * C1 + C2) & 0xFFFF;
  88       }
  89
  90       for (i=0; i<ldata; i++) {
  91         code[i+lrandom] = data[i] ^ ( r >> 8);
  92         r = ((code[i+lrandom] + r) * C1 + C2) & 0xFFFF;
  93       }
  94
  95       result = PyString_FromStringAndSize((const char *)code, ldata + lrandom);
  96       free(code);
  97       return result;
  98     }
  99     else return NULL;
 100
 101 }
 102
 103
 104
 105 /* exported methods */
 106
 107 static PyMethodDef t1code_methods[] = {
 108     {"decoder", py_decoder,  METH_VARARGS},
 109     {"encoder", py_encoder,  METH_VARARGS},
 110     {NULL, NULL}
 111 };
 112
 113 void init_t1code(void) {
 114     (void) Py_InitModule("_t1code", t1code_methods);
 115 }