
Buffer Protocol
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int PyObject_AsCharBuffer(PyObject *obj, const char **buffer, Py_ssize_t *buffer_len)

   Returns a pointer to a read-only memory location usable as
   character-based input.  The *obj* argument must support the single-
   segment character buffer interface.  On success, returns ``0``,
   sets *buffer* to the memory location and *buffer_len* to the buffer
   length.  Returns ``-1`` and sets a ``TypeError`` on error.

int PyObject_AsReadBuffer(PyObject *obj, const void **buffer, Py_ssize_t *buffer_len)

   Returns a pointer to a read-only memory location containing
   arbitrary data. The *obj* argument must support the single-segment
   readable buffer interface.  On success, returns ``0``, sets
   *buffer* to the memory location and *buffer_len* to the buffer
   length.  Returns ``-1`` and sets a ``TypeError`` on error.

int PyObject_CheckReadBuffer(PyObject *o)

   Returns ``1`` if *o* supports the single-segment readable buffer
   interface. Otherwise returns ``0``.

int PyObject_AsWriteBuffer(PyObject *obj, void **buffer, Py_ssize_t *buffer_len)

   Returns a pointer to a writable memory location.  The *obj*
   argument must support the single-segment, character buffer
   interface.  On success, returns ``0``, sets *buffer* to the memory
   location and *buffer_len* to the buffer length.  Returns ``-1`` and
   sets a ``TypeError`` on error.
