Give user the ability to specify buffer offsets in enqueue_transform

gpyfft/fft.py

@@ -137,14 +137,41 @@ def calculate_transform_strides(cls,
 
         return (tuple(t_strides), t_distance, batchsize, tuple(t_shape), axes_transform)
 
-    def enqueue(self, forward = True):
+    def enqueue(self, forward = True, wait_for_events = None):
+        return self.enqueue_arrays(forward=forward, data=self.data, result=self.result, wait_for_events=wait_for_events)
+
+    def enqueue_arrays(self, data = None, result = None, forward = True, wait_for_events = None):
         """enqueue transform"""
-        if self.result is not None:
-            events = self.plan.enqueue_transform((self.queue,), (self.data.data,), (self.result.data),
-                                        direction_forward = forward, temp_buffer = self.temp_buffer)
+        if data is None:
+            data = self.data
+        else:
+            assert data.shape == self.data.shape
+            assert data.strides == self.data.strides
+            assert data.dtype == self.data.dtype
+        if result is None:
+            result = self.result
         else:
-            events = self.plan.enqueue_transform((self.queue,), (self.data.data,),
-                                        direction_forward = forward, temp_buffer = self.temp_buffer)
+            assert result.shape == self.result.shape
+            assert result.strides == self.result.strides
+            assert result.dtype == self.result.dtype
+
+        # get buffer for data
+        if data.offset != 0:
+            data = data._new_with_changes(data=data.base_data[data.offset:], offset=0)
+        data_buffer = data.base_data
+
+        if result is not None:
+            # get buffer for result
+            if result.offset != 0:
+                result = result._new_with_changes(data=result.base_data[result.offset:], offset=0)
+            result_buffer = result.base_data
+
+            events = self.plan.enqueue_transform((self.queue,), (data_buffer,), (result_buffer),
+                                        direction_forward = forward, temp_buffer = self.temp_buffer, wait_for_events = wait_for_events)
+        else:
+            events = self.plan.enqueue_transform((self.queue,), (data_buffer,),
+                                        direction_forward = forward, temp_buffer = self.temp_buffer, wait_for_events = wait_for_events)
+
         return events
 
     def update_arrays(self, input_array, output_array):