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 <section id="buffers-and-memoryview-objects">
<h1>Buffers and Memoryview Objects<a class="headerlink" href="#buffers-and-memoryview-objects" title="Permalink to this headline">¶</a></h1>
Python objects implemented in C can export a group of functions called the
“buffer interface.” These functions can be used by an object to expose its
data in a raw, byte-oriented format. Clients of the object can use the buffer
interface to access the object data directly, without needing to copy it
first.
Two examples of objects that support the buffer interface are strings and
arrays. The string object exposes the character contents in the buffer
interface’s byte-oriented form. An array can only expose its contents via the
old-style buffer interface. This limitation does not apply to Python 3,
where <a class="reference internal" href="../library/stdtypes.html#memoryview" title="memoryview"><code class="xref py py-class docutils literal notranslate">memoryview</code></a> objects can be constructed from arrays, too.
Array elements may be multi-byte values.
An example user of the buffer interface is the file object’s <code class="xref py py-meth docutils literal notranslate">write()</code>
method. Any object that can export a series of bytes through the buffer
interface can be written to a file. There are a number of format codes to
<a class="reference internal" href="arg.html#c.PyArg_ParseTuple" title="PyArg_ParseTuple"><code class="xref c c-func docutils literal notranslate">PyArg_ParseTuple()</code></a> that operate against an object’s buffer interface,
returning data from the target object.
Starting from version 1.6, Python has been providing Python-level buffer
objects and a C-level buffer API so that any built-in or used-defined type can
expose its characteristics. Both, however, have been deprecated because of
various shortcomings, and have been officially removed in Python 3 in favour
of a new C-level buffer API and a new Python-level object named
<a class="reference internal" href="../library/stdtypes.html#memoryview" title="memoryview"><code class="xref py py-class docutils literal notranslate">memoryview</code></a>.
The new buffer API has been backported to Python 2.6, and the
<a class="reference internal" href="../library/stdtypes.html#memoryview" title="memoryview"><code class="xref py py-class docutils literal notranslate">memoryview</code></a> object has been backported to Python 2.7. It is strongly
advised to use them rather than the old APIs, unless you are blocked from
doing so for compatibility reasons.
<section id="the-new-style-py-buffer-struct">
<h2>The new-style Py_buffer struct<a class="headerlink" href="#the-new-style-py-buffer-struct" title="Permalink to this headline">¶</a></h2>
<dl class="c type">
<dt class="sig sig-object c" id="c.Py_buffer">
type Py_buffer<a class="headerlink" href="#c.Py_buffer" title="Permalink to this definition">¶</a> </dt>
<dd><dl class="c member">
<dt class="sig sig-object c" id="c.Py_buffer.buf">
void *buf<a class="headerlink" href="#c.Py_buffer.buf" title="Permalink to this definition">¶</a> </dt>
<dd>A pointer to the start of the memory for the object.
</dd></dl>

<dl class="c member">
<dt class="sig sig-object c">
Py_ssize_t len </dt>
<dd>The total length of the memory in bytes.
</dd></dl>

<dl class="c member">
<dt class="sig sig-object c" id="c.Py_buffer.readonly">
int readonly<a class="headerlink" href="#c.Py_buffer.readonly" title="Permalink to this definition">¶</a> </dt>
<dd>An indicator of whether the buffer is read only.
</dd></dl>

<dl class="c member">
<dt class="sig sig-object c">
const char *format </dt>
<dd>A NULL terminated string in <a class="reference internal" href="../library/struct.html#module-struct" title="struct: Interpret strings as packed binary data."><code class="xref py py-mod docutils literal notranslate">struct</code></a> module style syntax giving
the contents of the elements available through the buffer. If this is
NULL, <code class="docutils literal notranslate">&quot;B&quot;</code> (unsigned bytes) is assumed.
</dd></dl>

<dl class="c member">
<dt class="sig sig-object c" id="c.Py_buffer.ndim">
int ndim<a class="headerlink" href="#c.Py_buffer.ndim" title="Permalink to this definition">¶</a> </dt>
<dd>The number of dimensions the memory represents as a multi-dimensional
array. If it is <code class="docutils literal notranslate">0</code>, <a class="reference internal" href="#c.Py_buffer.strides" title="strides"><code class="xref c c-data docutils literal notranslate">strides</code></a> and <a class="reference internal" href="#c.Py_buffer.suboffsets" title="suboffsets"><code class="xref c c-data docutils literal notranslate">suboffsets</code></a> must be
NULL.
</dd></dl>

<dl class="c member">
<dt class="sig sig-object c" id="c.Py_buffer.shape">
Py_ssize_t *shape<a class="headerlink" href="#c.Py_buffer.shape" title="Permalink to this definition">¶</a> </dt>
<dd>An array of <code class="xref c c-type docutils literal notranslate">Py_ssize_t</code>s the length of <a class="reference internal" href="#c.Py_buffer.ndim" title="ndim"><code class="xref c c-data docutils literal notranslate">ndim</code></a> giving the
shape of the memory as a multi-dimensional array. Note that
<code class="docutils literal notranslate">((*shape)[0] * ... * (*shape)[ndims-1])*itemsize</code> should be equal to
<a class="reference internal" href="#c.Py_buffer.len" title="len"><code class="xref c c-data docutils literal notranslate">len</code></a>.
</dd></dl>

<dl class="c member">
<dt class="sig sig-object c" id="c.Py_buffer.strides">
Py_ssize_t *strides<a class="headerlink" href="#c.Py_buffer.strides" title="Permalink to this definition">¶</a> </dt>
<dd>An array of <code class="xref c c-type docutils literal notranslate">Py_ssize_t</code>s the length of <a class="reference internal" href="#c.Py_buffer.ndim" title="ndim"><code class="xref c c-data docutils literal notranslate">ndim</code></a> giving the
number of bytes to skip to get to a new element in each dimension.
</dd></dl>

<dl class="c member">
<dt class="sig sig-object c" id="c.Py_buffer.suboffsets">
Py_ssize_t *suboffsets<a class="headerlink" href="#c.Py_buffer.suboffsets" title="Permalink to this definition">¶</a> </dt>
<dd>An array of <code class="xref c c-type docutils literal notranslate">Py_ssize_t</code>s the length of <a class="reference internal" href="#c.Py_buffer.ndim" title="ndim"><code class="xref c c-data docutils literal notranslate">ndim</code></a>. If these
suboffset numbers are greater than or equal to 0, then the value stored
along the indicated dimension is a pointer and the suboffset value
dictates how many bytes to add to the pointer after de-referencing. A
suboffset value that it negative indicates that no de-referencing should
occur (striding in a contiguous memory block).
If all suboffsets are negative (i.e. no de-referencing is needed), then
this field must be NULL (the default value).
Here is a function that returns a pointer to the element in an N-D array
pointed to by an N-dimensional index when there are both non-NULL strides
and suboffsets:
<div class="highlight-default notranslate"><div class="highlight"><pre>void *get_item_pointer(int ndim, void *buf, Py_ssize_t *strides,
 Py_ssize_t *suboffsets, Py_ssize_t *indices) {
 char *pointer = (char*)buf;
 int i;
 for (i = 0; i &lt; ndim; i++) {
 pointer += strides[i] * indices[i];
 if (suboffsets[i] &gt;=0 ) {
 pointer = *((char**)pointer) + suboffsets[i];
 }
 }
 return (void*)pointer;
 }
</pre></div>
</div>
</dd></dl>

<dl class="c member">
<dt class="sig sig-object c" id="c.Py_buffer.itemsize">
Py_ssize_t itemsize<a class="headerlink" href="#c.Py_buffer.itemsize" title="Permalink to this definition">¶</a> </dt>
<dd>This is a storage for the itemsize (in bytes) of each element of the
shared memory. It is technically un-necessary as it can be obtained
using <a class="reference internal" href="#c.PyBuffer_SizeFromFormat" title="PyBuffer_SizeFromFormat"><code class="xref c c-func docutils literal notranslate">PyBuffer_SizeFromFormat()</code></a>, however an exporter may know
this information without parsing the format string and it is necessary
to know the itemsize for proper interpretation of striding. Therefore,
storing it is more convenient and faster.
</dd></dl>

<dl class="c member">
<dt class="sig sig-object c" id="c.Py_buffer.internal">
void *internal<a class="headerlink" href="#c.Py_buffer.internal" title="Permalink to this definition">¶</a> </dt>
<dd>This is for use internally by the exporting object. For example, this
might be re-cast as an integer by the exporter and used to store flags
about whether or not the shape, strides, and suboffsets arrays must be
freed when the buffer is released. The consumer should never alter this
value.
</dd></dl>

</dd></dl>

</section>
<section id="buffer-related-functions">
<h2>Buffer related functions<a class="headerlink" href="#buffer-related-functions" title="Permalink to this headline">¶</a></h2>
<dl class="c function">
<dt class="sig sig-object c" id="c.PyObject_CheckBuffer">
int PyObject_CheckBuffer(<a class="reference internal" href="structures.html#c.PyObject" title="PyObject">PyObject</a> *obj)<a class="headerlink" href="#c.PyObject_CheckBuffer" title="Permalink to this definition">¶</a> </dt>
<dd>Return <code class="docutils literal notranslate">1</code> if obj supports the buffer interface otherwise <code class="docutils literal notranslate">0</code>.
</dd></dl>

<dl class="c function">
<dt class="sig sig-object c" id="c.PyObject_GetBuffer">
int PyObject_GetBuffer(<a class="reference internal" href="structures.html#c.PyObject" title="PyObject">PyObject</a> *obj, <a class="reference internal" href="#c.Py_buffer" title="Py_buffer">Py_buffer</a> *view, int flags)<a class="headerlink" href="#c.PyObject_GetBuffer" title="Permalink to this definition">¶</a> </dt>
<dd>Export obj into a <a class="reference internal" href="#c.Py_buffer" title="Py_buffer"><code class="xref c c-type docutils literal notranslate">Py_buffer</code></a>, view. These arguments must
never be NULL. The flags argument is a bit field indicating what
kind of buffer the caller is prepared to deal with and therefore what
kind of buffer the exporter is allowed to return. The buffer interface
allows for complicated memory sharing possibilities, but some caller may
not be able to handle all the complexity but may want to see if the
exporter will let them take a simpler view to its memory.
Some exporters may not be able to share memory in every possible way and
may need to raise errors to signal to some consumers that something is
just not possible. These errors should be a <code class="xref py py-exc docutils literal notranslate">BufferError</code> unless
there is another error that is actually causing the problem. The
exporter can use flags information to simplify how much of the
<a class="reference internal" href="#c.Py_buffer" title="Py_buffer"><code class="xref c c-data docutils literal notranslate">Py_buffer</code></a> structure is filled in with non-default values and/or
raise an error if the object can’t support a simpler view of its memory.
<code class="docutils literal notranslate">0</code> is returned on success and <code class="docutils literal notranslate">-1</code> on error.
The following table gives possible values to the flags arguments.
<table class="docutils align-default">
<colgroup>
<col style="width: 38%" />
<col style="width: 62%" />
</colgroup>
<thead>
<tr class="row-odd"><th class="head">Flag</th>
<th class="head">Description</th>
</tr>
</thead>
<tbody>
<tr class="row-even"><td><code class="xref c c-macro docutils literal notranslate">PyBUF_SIMPLE</code></td>
<td>This is the default flag state. The returned
buffer may or may not have writable memory. The
format of the data will be assumed to be unsigned
bytes. This is a “stand-alone” flag constant. It
never needs to be ‘|’d to the others. The exporter
will raise an error if it cannot provide such a
contiguous buffer of bytes.</td>
</tr>
<tr class="row-odd"><td><code class="xref c c-macro docutils literal notranslate">PyBUF_WRITABLE</code></td>
<td>The returned buffer must be writable. If it is
not writable, then raise an error.</td>
</tr>
<tr class="row-even"><td><code class="xref c c-macro docutils literal notranslate">PyBUF_STRIDES</code></td>
<td>This implies <code class="xref c c-macro docutils literal notranslate">PyBUF_ND</code>. The returned
buffer must provide strides information (i.e. the
strides cannot be NULL). This would be used when
the consumer can handle strided, discontiguous
arrays. Handling strides automatically assumes
you can handle shape. The exporter can raise an
error if a strided representation of the data is
not possible (i.e. without the suboffsets).</td>
</tr>
<tr class="row-odd"><td><code class="xref c c-macro docutils literal notranslate">PyBUF_ND</code></td>
<td>The returned buffer must provide shape
information. The memory will be assumed C-style
contiguous (last dimension varies the
fastest). The exporter may raise an error if it
cannot provide this kind of contiguous buffer. If
this is not given then shape will be NULL.</td>
</tr>
<tr class="row-even"><td><code class="xref c c-macro docutils literal notranslate">PyBUF_C_CONTIGUOUS</code>
<code class="xref c c-macro docutils literal notranslate">PyBUF_F_CONTIGUOUS</code>
<code class="xref c c-macro docutils literal notranslate">PyBUF_ANY_CONTIGUOUS</code></td>
<td>These flags indicate that the contiguity returned
buffer must be respectively, C-contiguous (last
dimension varies the fastest), Fortran contiguous
(first dimension varies the fastest) or either
one. All of these flags imply
<code class="xref c c-macro docutils literal notranslate">PyBUF_STRIDES</code> and guarantee that the
strides buffer info structure will be filled in
correctly.</td>
</tr>
<tr class="row-odd"><td><code class="xref c c-macro docutils literal notranslate">PyBUF_INDIRECT</code></td>
<td>This flag indicates the returned buffer must have
suboffsets information (which can be NULL if no
suboffsets are needed). This can be used when
the consumer can handle indirect array
referencing implied by these suboffsets. This
implies <code class="xref c c-macro docutils literal notranslate">PyBUF_STRIDES</code>.</td>
</tr>
<tr class="row-even"><td><code class="xref c c-macro docutils literal notranslate">PyBUF_FORMAT</code></td>
<td>The returned buffer must have true format
information if this flag is provided. This would
be used when the consumer is going to be checking
for what ‘kind’ of data is actually stored. An
exporter should always be able to provide this
information if requested. If format is not
explicitly requested then the format must be
returned as NULL (which means <code class="docutils literal notranslate">'B'</code>, or
unsigned bytes)</td>
</tr>
<tr class="row-odd"><td><code class="xref c c-macro docutils literal notranslate">PyBUF_STRIDED</code></td>
<td>This is equivalent to <code class="docutils literal notranslate">(PyBUF_STRIDES |
PyBUF_WRITABLE)</code>.</td>
</tr>
<tr class="row-even"><td><code class="xref c c-macro docutils literal notranslate">PyBUF_STRIDED_RO</code></td>
<td>This is equivalent to <code class="docutils literal notranslate">(PyBUF_STRIDES)</code>.</td>
</tr>
<tr class="row-odd"><td><code class="xref c c-macro docutils literal notranslate">PyBUF_RECORDS</code></td>
<td>This is equivalent to <code class="docutils literal notranslate">(PyBUF_STRIDES |
PyBUF_FORMAT | PyBUF_WRITABLE)</code>.</td>
</tr>
<tr class="row-even"><td><code class="xref c c-macro docutils literal notranslate">PyBUF_RECORDS_RO</code></td>
<td>This is equivalent to <code class="docutils literal notranslate">(PyBUF_STRIDES |
PyBUF_FORMAT)</code>.</td>
</tr>
<tr class="row-odd"><td><code class="xref c c-macro docutils literal notranslate">PyBUF_FULL</code></td>
<td>This is equivalent to <code class="docutils literal notranslate">(PyBUF_INDIRECT |
PyBUF_FORMAT | PyBUF_WRITABLE)</code>.</td>
</tr>
<tr class="row-even"><td><code class="xref c c-macro docutils literal notranslate">PyBUF_FULL_RO</code></td>
<td>This is equivalent to <code class="docutils literal notranslate">(PyBUF_INDIRECT |
PyBUF_FORMAT)</code>.</td>
</tr>
<tr class="row-odd"><td><code class="xref c c-macro docutils literal notranslate">PyBUF_CONTIG</code></td>
<td>This is equivalent to <code class="docutils literal notranslate">(PyBUF_ND |
PyBUF_WRITABLE)</code>.</td>
</tr>
<tr class="row-even"><td><code class="xref c c-macro docutils literal notranslate">PyBUF_CONTIG_RO</code></td>
<td>This is equivalent to <code class="docutils literal notranslate">(PyBUF_ND)</code>.</td>
</tr>
</tbody>
</table>
</dd></dl>

<dl class="c function">
<dt class="sig sig-object c" id="c.PyBuffer_Release">
void PyBuffer_Release(<a class="reference internal" href="#c.Py_buffer" title="Py_buffer">Py_buffer</a> *view)<a class="headerlink" href="#c.PyBuffer_Release" title="Permalink to this definition">¶</a> </dt>
<dd>Release the buffer view. This should be called when the buffer
is no longer being used as it may free memory from it.
</dd></dl>

<dl class="c function">
<dt class="sig sig-object c" id="c.PyBuffer_SizeFromFormat">
Py_ssize_t PyBuffer_SizeFromFormat(const char*)<a class="headerlink" href="#c.PyBuffer_SizeFromFormat" title="Permalink to this definition">¶</a> </dt>
<dd>Return the implied <a class="reference internal" href="#c.Py_buffer.itemsize" title="Py_buffer.itemsize"><code class="xref c c-data docutils literal notranslate">itemsize</code></a> from the struct-stype
<a class="reference internal" href="#c.Py_buffer.format" title="Py_buffer.format"><code class="xref c c-data docutils literal notranslate">format</code></a>.
</dd></dl>

<dl class="c function">
<dt class="sig sig-object c" id="c.PyBuffer_IsContiguous">
int PyBuffer_IsContiguous(<a class="reference internal" href="#c.Py_buffer" title="Py_buffer">Py_buffer</a> *view, char fortran)<a class="headerlink" href="#c.PyBuffer_IsContiguous" title="Permalink to this definition">¶</a> </dt>
<dd>Return <code class="docutils literal notranslate">1</code> if the memory defined by the view is C-style (fortran is
<code class="docutils literal notranslate">'C'</code>) or Fortran-style (fortran is <code class="docutils literal notranslate">'F'</code>) contiguous or either one
(fortran is <code class="docutils literal notranslate">'A'</code>). Return <code class="docutils literal notranslate">0</code> otherwise.
</dd></dl>

<dl class="c function">
<dt class="sig sig-object c" id="c.PyBuffer_FillContiguousStrides">
void PyBuffer_FillContiguousStrides(int ndims, Py_ssize_t *shape, Py_ssize_t *strides, int itemsize, char fortran)<a class="headerlink" href="#c.PyBuffer_FillContiguousStrides" title="Permalink to this definition">¶</a> </dt>
<dd>Fill the strides array with byte-strides of a contiguous (C-style if
fortran is <code class="docutils literal notranslate">'C'</code> or Fortran-style if fortran is <code class="docutils literal notranslate">'F'</code>) array of the
given shape with the given number of bytes per element.
</dd></dl>

<dl class="c function">
<dt class="sig sig-object c" id="c.PyBuffer_FillInfo">
int PyBuffer_FillInfo(<a class="reference internal" href="#c.Py_buffer" title="Py_buffer">Py_buffer</a> *view, <a class="reference internal" href="structures.html#c.PyObject" title="PyObject">PyObject</a> *obj, void *buf, Py_ssize_t len, int readonly, int infoflags)<a class="headerlink" href="#c.PyBuffer_FillInfo" title="Permalink to this definition">¶</a> </dt>
<dd>Fill in a buffer-info structure, view, correctly for an exporter that can
only share a contiguous chunk of memory of “unsigned bytes” of the given
length. Return <code class="docutils literal notranslate">0</code> on success and <code class="docutils literal notranslate">-1</code> (with raising an error) on error.
</dd></dl>

</section>
<section id="memoryview-objects">
<h2>MemoryView objects<a class="headerlink" href="#memoryview-objects" title="Permalink to this headline">¶</a></h2>
<div class="versionadded">
New in version 2.7.
</div>
A <a class="reference internal" href="../library/stdtypes.html#memoryview" title="memoryview"><code class="xref py py-class docutils literal notranslate">memoryview</code></a> object exposes the new C level buffer interface as a
Python object which can then be passed around like any other object.
<dl class="c function">
<dt class="sig sig-object c" id="c.PyMemoryView_FromObject">
<a class="reference internal" href="structures.html#c.PyObject" title="PyObject">PyObject</a> *PyMemoryView_FromObject(<a class="reference internal" href="structures.html#c.PyObject" title="PyObject">PyObject</a> *obj)<a class="headerlink" href="#c.PyMemoryView_FromObject" title="Permalink to this definition">¶</a> </dt>
<dd>Create a memoryview object from an object that defines the new buffer
interface.
</dd></dl>

<dl class="c function">
<dt class="sig sig-object c" id="c.PyMemoryView_FromBuffer">
<a class="reference internal" href="structures.html#c.PyObject" title="PyObject">PyObject</a> *PyMemoryView_FromBuffer(<a class="reference internal" href="#c.Py_buffer" title="Py_buffer">Py_buffer</a> *view)<a class="headerlink" href="#c.PyMemoryView_FromBuffer" title="Permalink to this definition">¶</a> </dt>
<dd>Create a memoryview object wrapping the given buffer-info structure view.
The memoryview object then owns the buffer, which means you shouldn’t
try to release it yourself: it will be released on deallocation of the
memoryview object.
</dd></dl>

<dl class="c function">
<dt class="sig sig-object c" id="c.PyMemoryView_GetContiguous">
<a class="reference internal" href="structures.html#c.PyObject" title="PyObject">PyObject</a> *PyMemoryView_GetContiguous(<a class="reference internal" href="structures.html#c.PyObject" title="PyObject">PyObject</a> *obj, int buffertype, char order)<a class="headerlink" href="#c.PyMemoryView_GetContiguous" title="Permalink to this definition">¶</a> </dt>
<dd>Create a memoryview object to a contiguous chunk of memory (in either
‘C’ or ‘F’ortran order) from an object that defines the buffer
interface. If memory is contiguous, the memoryview object points to the
original memory. Otherwise copy is made and the memoryview points to a
new bytes object.
</dd></dl>

<dl class="c function">
<dt class="sig sig-object c" id="c.PyMemoryView_Check">
int PyMemoryView_Check(<a class="reference internal" href="structures.html#c.PyObject" title="PyObject">PyObject</a> *obj)<a class="headerlink" href="#c.PyMemoryView_Check" title="Permalink to this definition">¶</a> </dt>
<dd>Return true if the object obj is a memoryview object. It is not
currently allowed to create subclasses of <a class="reference internal" href="../library/stdtypes.html#memoryview" title="memoryview"><code class="xref py py-class docutils literal notranslate">memoryview</code></a>.
</dd></dl>

<dl class="c function">
<dt class="sig sig-object c" id="c.PyMemoryView_GET_BUFFER">
<a class="reference internal" href="#c.Py_buffer" title="Py_buffer">Py_buffer</a> *PyMemoryView_GET_BUFFER(<a class="reference internal" href="structures.html#c.PyObject" title="PyObject">PyObject</a> *obj)<a class="headerlink" href="#c.PyMemoryView_GET_BUFFER" title="Permalink to this definition">¶</a> </dt>
<dd>Return a pointer to the buffer-info structure wrapped by the given
object. The object must be a memoryview instance; this macro doesn’t
check its type, you must do it yourself or you will risk crashes.
</dd></dl>

</section>
<section id="old-style-buffer-objects">
<h2>Old-style buffer objects<a class="headerlink" href="#old-style-buffer-objects" title="Permalink to this headline">¶</a></h2>
More information on the old buffer interface is provided in the section
<a class="reference internal" href="typeobj.html#buffer-structs">Buffer Object Structures</a>, under the description for <a class="reference internal" href="typeobj.html#c.PyBufferProcs" title="PyBufferProcs"><code class="xref c c-type docutils literal notranslate">PyBufferProcs</code></a>.
A “buffer object” is defined in the <code class="file docutils literal notranslate">bufferobject.h</code> header (included by
<code class="file docutils literal notranslate">Python.h</code>). These objects look very similar to string objects at the
Python programming level: they support slicing, indexing, concatenation, and
some other standard string operations. However, their data can come from one
of two sources: from a block of memory, or from another object which exports
the buffer interface.
Buffer objects are useful as a way to expose the data from another object’s
buffer interface to the Python programmer. They can also be used as a
zero-copy slicing mechanism. Using their ability to reference a block of
memory, it is possible to expose any data to the Python programmer quite
easily. The memory could be a large, constant array in a C extension, it could
be a raw block of memory for manipulation before passing to an operating
system library, or it could be used to pass around structured data in its
native, in-memory format.
<dl class="c type">
<dt class="sig sig-object c" id="c.PyBufferObject">
type PyBufferObject<a class="headerlink" href="#c.PyBufferObject" title="Permalink to this definition">¶</a> </dt>
<dd>This subtype of <a class="reference internal" href="structures.html#c.PyObject" title="PyObject"><code class="xref c c-type docutils literal notranslate">PyObject</code></a> represents a buffer object.
</dd></dl>

<dl class="c var">
<dt class="sig sig-object c" id="c.PyBuffer_Type">
<a class="reference internal" href="type.html#c.PyTypeObject" title="PyTypeObject">PyTypeObject</a> PyBuffer_Type<a class="headerlink" href="#c.PyBuffer_Type" title="Permalink to this definition">¶</a> </dt>
<dd>The instance of <a class="reference internal" href="type.html#c.PyTypeObject" title="PyTypeObject"><code class="xref c c-type docutils literal notranslate">PyTypeObject</code></a> which represents the Python buffer type;
it is the same object as <code class="docutils literal notranslate">buffer</code> and <code class="docutils literal notranslate">types.BufferType</code> in the Python
layer. .
</dd></dl>

<dl class="c var">
<dt class="sig sig-object c" id="c.Py_END_OF_BUFFER">
int Py_END_OF_BUFFER<a class="headerlink" href="#c.Py_END_OF_BUFFER" title="Permalink to this definition">¶</a> </dt>
<dd>This constant may be passed as the size parameter to
<a class="reference internal" href="#c.PyBuffer_FromObject" title="PyBuffer_FromObject"><code class="xref c c-func docutils literal notranslate">PyBuffer_FromObject()</code></a> or <a class="reference internal" href="#c.PyBuffer_FromReadWriteObject" title="PyBuffer_FromReadWriteObject"><code class="xref c c-func docutils literal notranslate">PyBuffer_FromReadWriteObject()</code></a>. It
indicates that the new <a class="reference internal" href="#c.PyBufferObject" title="PyBufferObject"><code class="xref c c-type docutils literal notranslate">PyBufferObject</code></a> should refer to base
object from the specified offset to the end of its exported buffer.
Using this enables the caller to avoid querying the base object for its
length.
</dd></dl>

<dl class="c function">
<dt class="sig sig-object c" id="c.PyBuffer_Check">
int PyBuffer_Check(<a class="reference internal" href="structures.html#c.PyObject" title="PyObject">PyObject</a> *p)<a class="headerlink" href="#c.PyBuffer_Check" title="Permalink to this definition">¶</a> </dt>
<dd>Return true if the argument has type <a class="reference internal" href="#c.PyBuffer_Type" title="PyBuffer_Type"><code class="xref c c-data docutils literal notranslate">PyBuffer_Type</code></a>.
</dd></dl>

<dl class="c function">
<dt class="sig sig-object c" id="c.PyBuffer_FromObject">
<a class="reference internal" href="structures.html#c.PyObject" title="PyObject">PyObject</a> *PyBuffer_FromObject(<a class="reference internal" href="structures.html#c.PyObject" title="PyObject">PyObject</a> *base, Py_ssize_t offset, Py_ssize_t size)<a class="headerlink" href="#c.PyBuffer_FromObject" title="Permalink to this definition">¶</a> </dt>
<dd>Return a new read-only buffer object. This raises <code class="xref py py-exc docutils literal notranslate">TypeError</code> if
base doesn’t support the read-only buffer protocol or doesn’t provide
exactly one buffer segment, or it raises <code class="xref py py-exc docutils literal notranslate">ValueError</code> if offset is
less than zero. The buffer will hold a reference to the base object, and
the buffer’s contents will refer to the base object’s buffer interface,
starting as position offset and extending for size bytes. If size is
<code class="xref py py-const docutils literal notranslate">Py_END_OF_BUFFER</code>, then the new buffer’s contents extend to the
length of the base object’s exported buffer data.
<div class="versionchanged">
Changed in version 2.5: This function used an <code class="xref c c-type docutils literal notranslate">int</code> type for offset and size. This
might require changes in your code for properly supporting 64-bit
systems.
</div>
</dd></dl>

<dl class="c function">
<dt class="sig sig-object c" id="c.PyBuffer_FromReadWriteObject">
<a class="reference internal" href="structures.html#c.PyObject" title="PyObject">PyObject</a> *PyBuffer_FromReadWriteObject(<a class="reference internal" href="structures.html#c.PyObject" title="PyObject">PyObject</a> *base, Py_ssize_t offset, Py_ssize_t size)<a class="headerlink" href="#c.PyBuffer_FromReadWriteObject" title="Permalink to this definition">¶</a> </dt>
<dd>Return a new writable buffer object. Parameters and exceptions are similar
to those for <a class="reference internal" href="#c.PyBuffer_FromObject" title="PyBuffer_FromObject"><code class="xref c c-func docutils literal notranslate">PyBuffer_FromObject()</code></a>. If the base object does not
export the writeable buffer protocol, then <code class="xref py py-exc docutils literal notranslate">TypeError</code> is raised.
<div class="versionchanged">
Changed in version 2.5: This function used an <code class="xref c c-type docutils literal notranslate">int</code> type for offset and size. This
might require changes in your code for properly supporting 64-bit
systems.
</div>
</dd></dl>

<dl class="c function">
<dt class="sig sig-object c" id="c.PyBuffer_FromMemory">
<a class="reference internal" href="structures.html#c.PyObject" title="PyObject">PyObject</a> *PyBuffer_FromMemory(void *ptr, Py_ssize_t size)<a class="headerlink" href="#c.PyBuffer_FromMemory" title="Permalink to this definition">¶</a> </dt>
<dd>Return a new read-only buffer object that reads from a specified location
in memory, with a specified size. The caller is responsible for ensuring
that the memory buffer, passed in as ptr, is not deallocated while the
returned buffer object exists. Raises <code class="xref py py-exc docutils literal notranslate">ValueError</code> if size is less
than zero. Note that <code class="xref py py-const docutils literal notranslate">Py_END_OF_BUFFER</code> may not be passed for the
size parameter; <code class="xref py py-exc docutils literal notranslate">ValueError</code> will be raised in that case.
<div class="versionchanged">
Changed in version 2.5: This function used an <code class="xref c c-type docutils literal notranslate">int</code> type for size. This might require
changes in your code for properly supporting 64-bit systems.
</div>
</dd></dl>

<dl class="c function">
<dt class="sig sig-object c" id="c.PyBuffer_FromReadWriteMemory">
<a class="reference internal" href="structures.html#c.PyObject" title="PyObject">PyObject</a> *PyBuffer_FromReadWriteMemory(void *ptr, Py_ssize_t size)<a class="headerlink" href="#c.PyBuffer_FromReadWriteMemory" title="Permalink to this definition">¶</a> </dt>
<dd>Similar to <a class="reference internal" href="#c.PyBuffer_FromMemory" title="PyBuffer_FromMemory"><code class="xref c c-func docutils literal notranslate">PyBuffer_FromMemory()</code></a>, but the returned buffer is
writable.
<div class="versionchanged">
Changed in version 2.5: This function used an <code class="xref c c-type docutils literal notranslate">int</code> type for size. This might require
changes in your code for properly supporting 64-bit systems.
</div>
</dd></dl>

<dl class="c function">
<dt class="sig sig-object c" id="c.PyBuffer_New">
<a class="reference internal" href="structures.html#c.PyObject" title="PyObject">PyObject</a> *PyBuffer_New(Py_ssize_t size)<a class="headerlink" href="#c.PyBuffer_New" title="Permalink to this definition">¶</a> </dt>
<dd>Return a new writable buffer object that maintains its own memory buffer of
size bytes. <code class="xref py py-exc docutils literal notranslate">ValueError</code> is returned if size is not zero or
positive. Note that the memory buffer (as returned by
<a class="reference internal" href="objbuffer.html#c.PyObject_AsWriteBuffer" title="PyObject_AsWriteBuffer"><code class="xref c c-func docutils literal notranslate">PyObject_AsWriteBuffer()</code></a>) is not specifically aligned.
<div class="versionchanged">
Changed in version 2.5: This function used an <code class="xref c c-type docutils literal notranslate">int</code> type for size. This might require
changes in your code for properly supporting 64-bit systems.
</div>
</dd></dl>

</section>
</section>

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 <ul>
<li><a class="reference internal" href="#">Buffers and Memoryview Objects</a><ul>
<li><a class="reference internal" href="#the-new-style-py-buffer-struct">The new-style Py_buffer struct</a></li>
<li><a class="reference internal" href="#buffer-related-functions">Buffer related functions</a></li>
<li><a class="reference internal" href="#memoryview-objects">MemoryView objects</a></li>
<li><a class="reference internal" href="#old-style-buffer-objects">Old-style buffer objects</a></li>
</ul>
</li>
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