File size: 2,886 Bytes
f31fe4e | 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 | import cython
from cython.cimports.cpython import PyBUF_WRITABLE, PyBuffer_FillInfo
from cython.cimports.cpython.buffer import (
PyBUF_SIMPLE,
PyBuffer_Release,
PyObject_CheckBuffer,
PyObject_GetBuffer,
)
from cython.cimports.libc.string import memcpy
@cython.cclass
class ByteSource:
def __cinit__(self, owner):
self.owner = owner
try:
self.ptr = owner
except TypeError:
pass
else:
self.length = len(owner)
return
if PyObject_CheckBuffer(owner):
# Can very likely use PyBUF_ND instead of PyBUF_SIMPLE
res = PyObject_GetBuffer(owner, cython.address(self.view), PyBUF_SIMPLE)
if not res:
self.has_view = True
self.ptr = cython.cast(cython.p_uchar, self.view.buf)
self.length = self.view.len
return
raise TypeError("expected bytes, bytearray or memoryview")
def __dealloc__(self):
if self.has_view:
PyBuffer_Release(cython.address(self.view))
@cython.cfunc
def bytesource(obj, allow_none: cython.bint = False) -> ByteSource | None:
if allow_none and obj is None:
return None
elif isinstance(obj, ByteSource):
return obj
else:
return ByteSource(obj)
@cython.cclass
class Buffer:
"""A base class for PyAV objects which support the buffer protocol, such
as :class:`.Packet` and :class:`.Plane`.
"""
@cython.cfunc
def _buffer_size(self) -> cython.size_t:
return 0
def _buffer_ptr(self) -> cython.p_void:
return cython.NULL
def _buffer_writable(self) -> cython.bint:
return True
def __getbuffer__(self, view: cython.pointer[Py_buffer], flags: cython.int):
if flags & PyBUF_WRITABLE and not self._buffer_writable():
raise ValueError("buffer is not writable")
PyBuffer_FillInfo(view, self, self._buffer_ptr(), self._buffer_size(), 0, flags)
@property
def buffer_size(self):
return self._buffer_size()
@property
def buffer_ptr(self):
"""The memory address of the buffer."""
return cython.cast(cython.size_t, self._buffer_ptr())
def update(self, input):
"""Replace the data in this object with the given buffer.
Accepts anything that supports the `buffer protocol <https://docs.python.org/3/c-api/buffer.html>`_,
e.g. bytes, NumPy arrays, other :class:`Buffer` objects, etc..
"""
if not self._buffer_writable():
raise ValueError("buffer is not writable")
source: ByteSource = bytesource(input)
size: cython.size_t = self._buffer_size()
if source.length != size:
raise ValueError(f"got {source.length} bytes; need {size} bytes")
memcpy(self._buffer_ptr(), source.ptr, size)
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