| import cupy | |
| from cupy import _core | |
| _packbits_kernel = { | |
| 'big': _core.ElementwiseKernel( | |
| 'raw T a, raw int32 a_size', 'uint8 packed', | |
| '''for (int j = 0; j < 8; ++j) { | |
| int k = i * 8 + j; | |
| int bit = k < a_size && a[k] != 0; | |
| packed |= bit << (7 - j); | |
| }''', | |
| 'cupy_packbits_big' | |
| ), | |
| 'little': _core.ElementwiseKernel( | |
| 'raw T a, raw int32 a_size', 'uint8 packed', | |
| '''for (int j = 0; j < 8; ++j) { | |
| int k = i * 8 + j; | |
| int bit = k < a_size && a[k] != 0; | |
| packed |= bit << j; | |
| }''', | |
| 'cupy_packbits_little' | |
| ) | |
| } | |
| def packbits(a, axis=None, bitorder='big'): | |
| """Packs the elements of a binary-valued array into bits in a uint8 array. | |
| This function currently does not support ``axis`` option. | |
| Args: | |
| a (cupy.ndarray): Input array. | |
| axis (int, optional): Not supported yet. | |
| bitorder (str, optional): bit order to use when packing the array, | |
| allowed values are `'little'` and `'big'`. Defaults to `'big'`. | |
| Returns: | |
| cupy.ndarray: The packed array. | |
| .. note:: | |
| When the input array is empty, this function returns a copy of it, | |
| i.e., the type of the output array is not necessarily always uint8. | |
| This exactly follows the NumPy's behaviour (as of version 1.11), | |
| alghough this is inconsistent to the documentation. | |
| .. seealso:: :func:`numpy.packbits` | |
| """ | |
| if a.dtype.kind not in 'biu': | |
| raise TypeError( | |
| 'Expected an input array of integer or boolean data type') | |
| if axis is not None: | |
| raise NotImplementedError('axis option is not supported yet') | |
| if bitorder not in ('big', 'little'): | |
| raise ValueError("bitorder must be either 'big' or 'little'") | |
| a = a.ravel() | |
| packed_size = (a.size + 7) // 8 | |
| packed = cupy.zeros((packed_size,), dtype=cupy.uint8) | |
| return _packbits_kernel[bitorder](a, a.size, packed) | |
| _unpackbits_kernel = { | |
| 'big': _core.ElementwiseKernel( | |
| 'raw uint8 a', 'T unpacked', | |
| 'unpacked = (a[i / 8] >> (7 - i % 8)) & 1;', | |
| 'cupy_unpackbits_big' | |
| ), | |
| 'little': _core.ElementwiseKernel( | |
| 'raw uint8 a', 'T unpacked', | |
| 'unpacked = (a[i / 8] >> (i % 8)) & 1;', | |
| 'cupy_unpackbits_little' | |
| ) | |
| } | |
| def unpackbits(a, axis=None, bitorder='big'): | |
| """Unpacks elements of a uint8 array into a binary-valued output array. | |
| This function currently does not support ``axis`` option. | |
| Args: | |
| a (cupy.ndarray): Input array. | |
| bitorder (str, optional): bit order to use when unpacking the array, | |
| allowed values are `'little'` and `'big'`. Defaults to `'big'`. | |
| Returns: | |
| cupy.ndarray: The unpacked array. | |
| .. seealso:: :func:`numpy.unpackbits` | |
| """ | |
| if a.dtype != cupy.uint8: | |
| raise TypeError('Expected an input array of unsigned byte data type') | |
| if axis is not None: | |
| raise NotImplementedError('axis option is not supported yet') | |
| if bitorder not in ('big', 'little'): | |
| raise ValueError("bitorder must be either 'big' or 'little'") | |
| unpacked = cupy.ndarray((a.size * 8), dtype=cupy.uint8) | |
| return _unpackbits_kernel[bitorder](a, unpacked) | |