1 files changed, 146 insertions, 0 deletions
diff --git a/src/silx/math/fft/basefft.py b/src/silx/math/fft/basefft.py
new file mode 100644
index 0000000..854ca37
--- /dev/null
+++ b/src/silx/math/fft/basefft.py
@@ -0,0 +1,146 @@
+#!/usr/bin/env python
+# coding: utf-8
+# /*##########################################################################
+#
+# Copyright (c) 2018 European Synchrotron Radiation Facility
+#
+# Permission is hereby granted, free of charge, to any person obtaining a copy
+# of this software and associated documentation files (the "Software"), to deal
+# in the Software without restriction, including without limitation the rights
+# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+# copies of the Software, and to permit persons to whom the Software is
+# furnished to do so, subject to the following conditions:
+#
+# The above copyright notice and this permission notice shall be included in
+# all copies or substantial portions of the Software.
+#
+# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+# THE SOFTWARE.
+#
+# ###########################################################################*/
+import numpy as np
+from pkg_resources import parse_version
+
+
+def check_version(package, required_version):
+    """
+    Check whether a given package version is superior or equal to required_version.
+    """
+    try:
+        ver = getattr(package, "__version__")
+    except AttributeError:
+        try:
+            ver = getattr(package, "version")
+        except Exception:
+            return False
+    req_v = parse_version(required_version)
+    ver_v = parse_version(ver)
+    return ver_v >= req_v
+
+
+class BaseFFT(object):
+    """
+    Base class for all FFT backends.
+    """
+    def __init__(self, **kwargs):
+        self.__get_args(**kwargs)
+
+        if self.shape is None and self.dtype is None and self.template is None:
+            raise ValueError("Please provide either (shape and dtype) or template")
+        if self.template is not None:
+            self.shape = self.template.shape
+            self.dtype = self.template.dtype
+        self.user_data = self.template
+        self.data_allocated = False
+        self.__calc_axes()
+        self.__set_dtypes()
+        self.__calc_shape()
+
+    def __get_args(self, **kwargs):
+        expected_args = {
+            "shape": None,
+            "dtype": None,
+            "template": None,
+            "shape_out": None,
+            "axes": None,
+            "normalize": "rescale",
+        }
+        for arg_name, default_val in expected_args.items():
+            if arg_name not in kwargs:
+                # Base class was not instantiated properly
+                raise ValueError("Please provide argument %s" % arg_name)
+            setattr(self, arg_name, default_val)
+        for arg_name, arg_val in kwargs.items():
+            setattr(self, arg_name, arg_val)
+
+    def __set_dtypes(self):
+        dtypes_mapping = {
+            np.dtype("float32"): np.complex64,
+            np.dtype("float64"): np.complex128,
+            np.dtype("complex64"): np.complex64,
+            np.dtype("complex128"): np.complex128
+        }
+        dp = {
+            np.dtype("float32"): np.float64,
+            np.dtype("complex64"): np.complex128
+        }
+        self.dtype_in = np.dtype(self.dtype)
+        if self.dtype_in not in dtypes_mapping:
+            raise ValueError("Invalid input data type: got %s" %
+                self.dtype_in
+            )
+        self.dtype_out = dtypes_mapping[self.dtype_in]
+
+    def __calc_shape(self):
+        # TODO allow for C2C even for real input data (?)
+        if self.dtype_in in [np.float32, np.float64]:
+            last_dim = self.shape[-1]//2 + 1
+            # FFTW convention
+            self.shape_out = self.shape[:-1] + (self.shape[-1]//2 + 1,)
+        else:
+            self.shape_out = self.shape
+
+    def __calc_axes(self):
+        default_axes = tuple(range(len(self.shape)))
+        if self.axes is None:
+            self.axes = default_axes
+            self.user_axes = None
+        else:
+            self.user_axes = self.axes
+            # Handle possibly negative axes
+            self.axes = tuple(np.array(default_axes)[np.array(self.user_axes)])
+
+    def _allocate(self, shape, dtype):
+        raise ValueError("This should be implemented by back-end FFT")
+
+    def set_data(self, dst, src, shape, dtype, copy=True):
+        raise ValueError("This should be implemented by back-end FFT")
+
+    def allocate_arrays(self):
+        if not(self.data_allocated):
+            self.data_in = self._allocate(self.shape, self.dtype_in)
+            self.data_out = self._allocate(self.shape_out, self.dtype_out)
+            self.data_allocated = True
+
+    def set_input_data(self, data, copy=True):
+        if data is None:
+            return self.data_in
+        else:
+            return self.set_data(self.data_in, data, self.shape, self.dtype_in, copy=copy, name="data_in")
+
+    def set_output_data(self, data, copy=True):
+        if data is None:
+            return self.data_out
+        else:
+            return self.set_data(self.data_out, data, self.shape_out, self.dtype_out, copy=copy, name="data_out")
+
+    def fft(self, array, **kwargs):
+        raise ValueError("This should be implemented by back-end FFT")
+
+    def ifft(self, array, **kwargs):
+        raise ValueError("This should be implemented by back-end FFT")