Basic support for OpenCL (experimental)

Basic support for OpenCL

Problem: OpenCL cannot import stdint.h. Temporary fix: define custom opencl_stdint.h (defines currently only int64_t `)

TODO:

• implement opencl_stdint.h
• implement shard_mem, textures, built-in functions
• avoid CUDA intrinsics (fast_div)

pystencils/backends/cbackend.py

@@ -213,7 +213,11 @@ class CBackend:
 
     def _print_SympyAssignment(self, node):
         if node.is_declaration:
-            data_type = "const " + self._print(node.lhs.dtype) + " " if node.is_const else self._print(node.lhs.dtype) + " "
+            if node.is_const:
+                prefix = 'const '
+            else:
+                prefix = ''
+            data_type = prefix + self._print(node.lhs.dtype) + " "
             return "%s%s = %s;" % (data_type, self.sympy_printer.doprint(node.lhs),
                                    self.sympy_printer.doprint(node.rhs))
         else: