python-mraa.i: Add typemaps to make I2c::{read,write} natural

Typemaps now make uint8_t *data, int length map to a bytearray

Signed-off-by: Brendan Le Foll <brendan.le.foll@intel.com>

src/python/python-mraa.i

@@ -2,5 +2,52 @@
 
 %feature("autodoc", "3");
 
+%include typemaps.i
+%include carrays.i
+
+%array_class(uint8_t, uint8Array);
+
+// i2c write()
+%typemap(in) (const uint8_t *data, int length) {
+  if (PyByteArray_Check($input)) {
+    // whilst this may seem 'hopeful' it turns out this is safe
+    $1 = (uint8_t*) PyByteArray_AsString($input);
+    $2 = PyByteArray_Size($input);
+  }
+}
+
+%typemap(out) uint8_t*
+{
+  // need to loop over length
+  $result = PyByteArray_FromStringAndSize((char*) $1, arg2);
+}
+
+%newobject I2c::read(uint8_t *data, int length);
+
+%typemap(in) (uint8_t *data, int length) {
+   if (!PyInt_Check($input)) {
+       PyErr_SetString(PyExc_ValueError, "Expecting an integer");
+       return NULL;
+   }
+   $2 = PyInt_AsLong($input);
+   if ($2 < 0) {
+       PyErr_SetString(PyExc_ValueError, "Positive integer expected");
+       return NULL;
+   }
+   $1 = (uint8_t*) malloc($2 * sizeof(uint8_t));
+}
+
+%typemap(argout) (uint8_t *data, int length) {
+   Py_XDECREF($result);   /* Blow away any previous result */
+   if (result < 0) {      /* Check for I/O error */
+       free($1);
+       PyErr_SetFromErrno(PyExc_IOError);
+       return NULL;
+   }
+   // Append output value $1 to $result
+   $result = PyByteArray_FromStringAndSize((char*) $1, result);
+   free($1);
+}
+
 %include ../mraa.i