import sys
import numpy as np
import numba
@numba.njit(inline='always', cache=True)
def byteswap_2_straight(inp, out):
for i in range(inp.shape[0] // 2):
out[i * 2 + 0] = inp[i * 2 + 1]
out[i * 2 + 1] = inp[i * 2 + 0]
@numba.njit(inline='always', cache=True)
def byteswap_2_decode(inp, out):
for i in range(inp.shape[0] // 2):
o0 = inp[i * 2 + 0] << 8
o1 = inp[i * 2 + 1] << 0
out[i] = o0 | o1
@numba.njit(inline='always', cache=True)
def byteswap_4_straight(inp, out):
for i in range(inp.shape[0] // 4):
out[i * 4 + 3] = inp[i * 4 + 0]
out[i * 4 + 2] = inp[i * 4 + 1]
out[i * 4 + 1] = inp[i * 4 + 2]
out[i * 4 + 0] = inp[i * 4 + 3]
@numba.njit(inline='always', cache=True)
def byteswap_4_decode(inp, out):
for i in range(inp.shape[0] // 4):
o0 = inp[i * 4 + 0] << 24
o1 = inp[i * 4 + 1] << 16
o2 = inp[i * 4 + 2] << 8
o3 = inp[i * 4 + 3] << 0
out[i] = o0 + o1 + o2 + o3
@numba.njit(inline='always', cache=True)
def byteswap_8_straight(inp, out):
for i in range(inp.shape[0] // 8):
out[i * 8 + 7] = inp[i * 8 + 0]
out[i * 8 + 6] = inp[i * 8 + 1]
out[i * 8 + 5] = inp[i * 8 + 2]
out[i * 8 + 4] = inp[i * 8 + 3]
out[i * 8 + 3] = inp[i * 8 + 4]
out[i * 8 + 2] = inp[i * 8 + 5]
out[i * 8 + 1] = inp[i * 8 + 6]
out[i * 8 + 0] = inp[i * 8 + 7]
@numba.njit(inline='always', cache=True)
def byteswap_8_decode(inp, out):
for i in range(inp.shape[0] // 8):
o0 = inp[i * 8 + 0] << 56
o1 = inp[i * 8 + 1] << 48
o2 = inp[i * 8 + 2] << 40
o3 = inp[i * 8 + 3] << 32
o4 = inp[i * 8 + 4] << 24
o5 = inp[i * 8 + 5] << 16
o6 = inp[i * 8 + 6] << 8
o7 = inp[i * 8 + 7] << 0
out[i] = o0 + o1 + o2 + o3 + o4 + o5 + o6 + o7
@numba.njit(inline='always', cache=True)
def default_decode(inp, out, idx, native_dtype, rr, origin, shape, ds_shape):
out[idx, :] = inp.view(native_dtype)
[docs]
@numba.njit(inline='always', cache=True)
def decode_swap_2(inp, out, idx, native_dtype, rr, origin, shape, ds_shape):
byteswap_2_decode(inp, out=out[idx])
[docs]
@numba.njit(inline='always', cache=True)
def decode_swap_4(inp, out, idx, native_dtype, rr, origin, shape, ds_shape):
byteswap_4_decode(inp, out=out[idx])
@numba.njit(inline='always', cache=True)
def decode_swap_8(inp, out, idx, native_dtype, rr, origin, shape, ds_shape):
byteswap_8_decode(inp, out=out[idx])
@numba.njit(inline='always', cache=True)
def decode_swap_only_2(inp, out, idx, native_dtype, rr, origin, shape, ds_shape):
byteswap_2_straight(inp, out=out[idx].view(np.uint8))
@numba.njit(inline='always', cache=True)
def decode_swap_only_4(inp, out, idx, native_dtype, rr, origin, shape, ds_shape):
byteswap_4_straight(inp, out=out[idx].view(np.uint8))
@numba.njit(inline='always', cache=True)
def decode_swap_only_8(inp, out, idx, native_dtype, rr, origin, shape, ds_shape):
byteswap_8_straight(inp, out=out[idx].view(np.uint8))
def _convert_byteorder_eq(order):
if order != '=':
return order
return {
'little': '<',
'big': '>',
}[sys.byteorder]
[docs]
class Decoder:
[docs]
def do_clear(self):
return False
[docs]
def get_native_dtype(self, inp_native_dtype, read_dtype):
return inp_native_dtype
[docs]
def get_decode(self, native_dtype, read_dtype):
raise NotImplementedError()
[docs]
class DtypeConversionDecoder(Decoder):
def _need_byteswap(self, native_dtype, read_dtype):
native_dtype = np.dtype(native_dtype)
read_dtype = np.dtype(read_dtype)
nd_order = _convert_byteorder_eq(native_dtype.byteorder)
rd_order = _convert_byteorder_eq(read_dtype.byteorder)
return nd_order != rd_order and native_dtype.itemsize > 1
def _swapping_decode(self, native_dtype):
return {
2: decode_swap_2,
4: decode_swap_4,
8: decode_swap_8,
}[native_dtype.itemsize]
def _swap_only_decode(self, native_dtype):
return {
2: decode_swap_only_2,
4: decode_swap_only_4,
8: decode_swap_only_8,
}[native_dtype.itemsize]
[docs]
def get_decode(self, native_dtype, read_dtype):
native_dtype = np.dtype(native_dtype)
read_dtype = np.dtype(read_dtype)
if not self._need_byteswap(native_dtype, read_dtype):
return default_decode
if native_dtype.kind in ('f', 'c'):
# TODO: can implement f32->f32 and f64->f64 by straight swapping, and
# other conversions via a two-step decoding process
raise NotImplementedError(
"byte swapping for floats not implemented yet"
)
return self._swapping_decode(native_dtype)
[docs]
def get_native_dtype(self, inp_native_dtype, read_dtype):
if self._need_byteswap(inp_native_dtype, read_dtype):
return np.dtype(np.uint8)
return np.dtype(inp_native_dtype)