Make shuffle pyx functions noexcept (#477)

* Make shuffle pyx functions return int

* Update numcodecs/_shuffle.pyx

Co-authored-by: jakirkham <[email protected]>

* Update numcodecs/_shuffle.pyx

Co-authored-by: jakirkham <[email protected]>

* Note shuffle pyx functions are `noexcept`

---------

Co-authored-by: jakirkham <[email protected]>

Author: martindurant

docs/release.rst

@@ -14,8 +14,10 @@ Release notes
 Fix
 ~~~
 
-* `Codec` is now derived from `abc.ABC`
+* ``Codec`` is now derived from ``abc.ABC``
   By :user:`Mads R. B. Kristensen <madsbk>`, :issue:`472`.
+* Make shuffle pyx functions ``noexcept``
+  By :user:`Martin Durant <martindurant>`, :issue:`477`.
 
 .. _release_0.12.0:
 

numcodecs/_shuffle.pyx

@@ -8,7 +8,7 @@ cimport cython
 
 @cython.boundscheck(False)
 @cython.wraparound(False)
-cpdef void _doShuffle(const unsigned char[::1] src, unsigned char[::1] des, Py_ssize_t element_size) nogil:
+cpdef void _doShuffle(const unsigned char[::1] src, unsigned char[::1] des, Py_ssize_t element_size) noexcept nogil:
     cdef Py_ssize_t count, i, j, offset, byte_index
     count = len(src) // element_size
     for i in range(count):
@@ -20,7 +20,7 @@ cpdef void _doShuffle(const unsigned char[::1] src, unsigned char[::1] des, Py_s
 
 @cython.boundscheck(False)
 @cython.wraparound(False)
-cpdef void _doUnshuffle(const unsigned char[::1] src, unsigned char[::1] des, Py_ssize_t element_size) nogil:
+cpdef void _doUnshuffle(const unsigned char[::1] src, unsigned char[::1] des, Py_ssize_t element_size) noexcept nogil:
     cdef Py_ssize_t count, i, j, offset, byte_index
     count = len(src) // element_size
     for i in range(element_size):