added cuda extension for efficent implementation

alt_cuda_corr/setup.py

@@ -0,0 +1,15 @@
+from setuptools import setup
+from torch.utils.cpp_extension import BuildExtension, CUDAExtension
+
+
+setup(
+    name='correlation',
+    ext_modules=[
+        CUDAExtension('alt_cuda_corr',
+            sources=['correlation.cpp', 'correlation_kernel.cu'],
+            extra_compile_args={'cxx': [], 'nvcc': ['-O3']}),
+    ],
+    cmdclass={
+        'build_ext': BuildExtension
+    })
+