You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
85 lines
2.3 KiB
85 lines
2.3 KiB
"""
|
|
The following are faster versions of struct.unpack that avoid the overhead of Python
|
|
function calls.
|
|
|
|
In the SAS7BDAT parser, they may be called up to (n_rows * n_cols) times.
|
|
"""
|
|
from cython cimport Py_ssize_t
|
|
from libc.stdint cimport (
|
|
uint16_t,
|
|
uint32_t,
|
|
uint64_t,
|
|
)
|
|
from libc.string cimport memcpy
|
|
|
|
|
|
def read_float_with_byteswap(bytes data, Py_ssize_t offset, bint byteswap):
|
|
cdef uint32_t value
|
|
assert offset + sizeof(value) < len(data)
|
|
cdef const void *ptr = <unsigned char*>(data) + offset
|
|
memcpy(&value, ptr, sizeof(value))
|
|
if byteswap:
|
|
value = _byteswap4(value)
|
|
|
|
cdef float res
|
|
memcpy(&res, &value, sizeof(res))
|
|
return res
|
|
|
|
|
|
def read_double_with_byteswap(bytes data, Py_ssize_t offset, bint byteswap):
|
|
cdef uint64_t value
|
|
assert offset + sizeof(value) < len(data)
|
|
cdef const void *ptr = <unsigned char*>(data) + offset
|
|
memcpy(&value, ptr, sizeof(value))
|
|
if byteswap:
|
|
value = _byteswap8(value)
|
|
|
|
cdef double res
|
|
memcpy(&res, &value, sizeof(res))
|
|
return res
|
|
|
|
|
|
def read_uint16_with_byteswap(bytes data, Py_ssize_t offset, bint byteswap):
|
|
cdef uint16_t res
|
|
assert offset + sizeof(res) < len(data)
|
|
memcpy(&res, <const unsigned char*>(data) + offset, sizeof(res))
|
|
if byteswap:
|
|
res = _byteswap2(res)
|
|
return res
|
|
|
|
|
|
def read_uint32_with_byteswap(bytes data, Py_ssize_t offset, bint byteswap):
|
|
cdef uint32_t res
|
|
assert offset + sizeof(res) < len(data)
|
|
memcpy(&res, <const unsigned char*>(data) + offset, sizeof(res))
|
|
if byteswap:
|
|
res = _byteswap4(res)
|
|
return res
|
|
|
|
|
|
def read_uint64_with_byteswap(bytes data, Py_ssize_t offset, bint byteswap):
|
|
cdef uint64_t res
|
|
assert offset + sizeof(res) < len(data)
|
|
memcpy(&res, <const unsigned char*>(data) + offset, sizeof(res))
|
|
if byteswap:
|
|
res = _byteswap8(res)
|
|
return res
|
|
|
|
|
|
# Byteswapping
|
|
|
|
cdef extern from *:
|
|
"""
|
|
#ifdef _MSC_VER
|
|
#define _byteswap2 _byteswap_ushort
|
|
#define _byteswap4 _byteswap_ulong
|
|
#define _byteswap8 _byteswap_uint64
|
|
#else
|
|
#define _byteswap2 __builtin_bswap16
|
|
#define _byteswap4 __builtin_bswap32
|
|
#define _byteswap8 __builtin_bswap64
|
|
#endif
|
|
"""
|
|
uint16_t _byteswap2(uint16_t)
|
|
uint32_t _byteswap4(uint32_t)
|
|
uint64_t _byteswap8(uint64_t)
|
|
|