mirror of https://github.com/python/cpython
618 lines
22 KiB
ReStructuredText
618 lines
22 KiB
ReStructuredText
.. highlight:: c
|
|
|
|
.. _longobjects:
|
|
|
|
Integer Objects
|
|
---------------
|
|
|
|
.. index:: pair: object; long integer
|
|
pair: object; integer
|
|
|
|
All integers are implemented as "long" integer objects of arbitrary size.
|
|
|
|
On error, most ``PyLong_As*`` APIs return ``(return type)-1`` which cannot be
|
|
distinguished from a number. Use :c:func:`PyErr_Occurred` to disambiguate.
|
|
|
|
.. c:type:: PyLongObject
|
|
|
|
This subtype of :c:type:`PyObject` represents a Python integer object.
|
|
|
|
|
|
.. c:var:: PyTypeObject PyLong_Type
|
|
|
|
This instance of :c:type:`PyTypeObject` represents the Python integer type.
|
|
This is the same object as :class:`int` in the Python layer.
|
|
|
|
|
|
.. c:function:: int PyLong_Check(PyObject *p)
|
|
|
|
Return true if its argument is a :c:type:`PyLongObject` or a subtype of
|
|
:c:type:`PyLongObject`. This function always succeeds.
|
|
|
|
|
|
.. c:function:: int PyLong_CheckExact(PyObject *p)
|
|
|
|
Return true if its argument is a :c:type:`PyLongObject`, but not a subtype of
|
|
:c:type:`PyLongObject`. This function always succeeds.
|
|
|
|
|
|
.. c:function:: PyObject* PyLong_FromLong(long v)
|
|
|
|
Return a new :c:type:`PyLongObject` object from *v*, or ``NULL`` on failure.
|
|
|
|
The current implementation keeps an array of integer objects for all integers
|
|
between ``-5`` and ``256``. When you create an int in that range you actually
|
|
just get back a reference to the existing object.
|
|
|
|
|
|
.. c:function:: PyObject* PyLong_FromUnsignedLong(unsigned long v)
|
|
|
|
Return a new :c:type:`PyLongObject` object from a C :c:expr:`unsigned long`, or
|
|
``NULL`` on failure.
|
|
|
|
|
|
.. c:function:: PyObject* PyLong_FromSsize_t(Py_ssize_t v)
|
|
|
|
Return a new :c:type:`PyLongObject` object from a C :c:type:`Py_ssize_t`, or
|
|
``NULL`` on failure.
|
|
|
|
|
|
.. c:function:: PyObject* PyLong_FromSize_t(size_t v)
|
|
|
|
Return a new :c:type:`PyLongObject` object from a C :c:type:`size_t`, or
|
|
``NULL`` on failure.
|
|
|
|
|
|
.. c:function:: PyObject* PyLong_FromLongLong(long long v)
|
|
|
|
Return a new :c:type:`PyLongObject` object from a C :c:expr:`long long`, or ``NULL``
|
|
on failure.
|
|
|
|
|
|
.. c:function:: PyObject* PyLong_FromInt32(int32_t value)
|
|
PyObject* PyLong_FromInt64(int64_t value)
|
|
|
|
Return a new :c:type:`PyLongObject` object from a signed C
|
|
:c:expr:`int32_t` or :c:expr:`int64_t`, or ``NULL``
|
|
with an exception set on failure.
|
|
|
|
.. versionadded:: 3.14
|
|
|
|
|
|
.. c:function:: PyObject* PyLong_FromUnsignedLongLong(unsigned long long v)
|
|
|
|
Return a new :c:type:`PyLongObject` object from a C :c:expr:`unsigned long long`,
|
|
or ``NULL`` on failure.
|
|
|
|
|
|
.. c:function:: PyObject* PyLong_FromUInt32(uint32_t value)
|
|
PyObject* PyLong_FromUInt64(uint64_t value)
|
|
|
|
Return a new :c:type:`PyLongObject` object from an unsigned C
|
|
:c:expr:`uint32_t` or :c:expr:`uint64_t`, or ``NULL``
|
|
with an exception set on failure.
|
|
|
|
.. versionadded:: 3.14
|
|
|
|
|
|
.. c:function:: PyObject* PyLong_FromDouble(double v)
|
|
|
|
Return a new :c:type:`PyLongObject` object from the integer part of *v*, or
|
|
``NULL`` on failure.
|
|
|
|
|
|
.. c:function:: PyObject* PyLong_FromString(const char *str, char **pend, int base)
|
|
|
|
Return a new :c:type:`PyLongObject` based on the string value in *str*, which
|
|
is interpreted according to the radix in *base*, or ``NULL`` on failure. If
|
|
*pend* is non-``NULL``, *\*pend* will point to the end of *str* on success or
|
|
to the first character that could not be processed on error. If *base* is ``0``,
|
|
*str* is interpreted using the :ref:`integers` definition; in this case, leading
|
|
zeros in a non-zero decimal number raises a :exc:`ValueError`. If *base* is not
|
|
``0``, it must be between ``2`` and ``36``, inclusive. Leading and trailing
|
|
whitespace and single underscores after a base specifier and between digits are
|
|
ignored. If there are no digits or *str* is not NULL-terminated following the
|
|
digits and trailing whitespace, :exc:`ValueError` will be raised.
|
|
|
|
.. seealso:: :c:func:`PyLong_AsNativeBytes()` and
|
|
:c:func:`PyLong_FromNativeBytes()` functions can be used to convert
|
|
a :c:type:`PyLongObject` to/from an array of bytes in base ``256``.
|
|
|
|
|
|
.. c:function:: PyObject* PyLong_FromUnicodeObject(PyObject *u, int base)
|
|
|
|
Convert a sequence of Unicode digits in the string *u* to a Python integer
|
|
value.
|
|
|
|
.. versionadded:: 3.3
|
|
|
|
|
|
.. c:function:: PyObject* PyLong_FromVoidPtr(void *p)
|
|
|
|
Create a Python integer from the pointer *p*. The pointer value can be
|
|
retrieved from the resulting value using :c:func:`PyLong_AsVoidPtr`.
|
|
|
|
|
|
.. c:function:: PyObject* PyLong_FromNativeBytes(const void* buffer, size_t n_bytes, int flags)
|
|
|
|
Create a Python integer from the value contained in the first *n_bytes* of
|
|
*buffer*, interpreted as a two's-complement signed number.
|
|
|
|
*flags* are as for :c:func:`PyLong_AsNativeBytes`. Passing ``-1`` will select
|
|
the native endian that CPython was compiled with and assume that the
|
|
most-significant bit is a sign bit. Passing
|
|
``Py_ASNATIVEBYTES_UNSIGNED_BUFFER`` will produce the same result as calling
|
|
:c:func:`PyLong_FromUnsignedNativeBytes`. Other flags are ignored.
|
|
|
|
.. versionadded:: 3.13
|
|
|
|
|
|
.. c:function:: PyObject* PyLong_FromUnsignedNativeBytes(const void* buffer, size_t n_bytes, int flags)
|
|
|
|
Create a Python integer from the value contained in the first *n_bytes* of
|
|
*buffer*, interpreted as an unsigned number.
|
|
|
|
*flags* are as for :c:func:`PyLong_AsNativeBytes`. Passing ``-1`` will select
|
|
the native endian that CPython was compiled with and assume that the
|
|
most-significant bit is not a sign bit. Flags other than endian are ignored.
|
|
|
|
.. versionadded:: 3.13
|
|
|
|
|
|
.. c:function:: long PyLong_AsLong(PyObject *obj)
|
|
|
|
.. index::
|
|
single: LONG_MAX (C macro)
|
|
single: OverflowError (built-in exception)
|
|
|
|
Return a C :c:expr:`long` representation of *obj*. If *obj* is not an
|
|
instance of :c:type:`PyLongObject`, first call its :meth:`~object.__index__` method
|
|
(if present) to convert it to a :c:type:`PyLongObject`.
|
|
|
|
Raise :exc:`OverflowError` if the value of *obj* is out of range for a
|
|
:c:expr:`long`.
|
|
|
|
Returns ``-1`` on error. Use :c:func:`PyErr_Occurred` to disambiguate.
|
|
|
|
.. versionchanged:: 3.8
|
|
Use :meth:`~object.__index__` if available.
|
|
|
|
.. versionchanged:: 3.10
|
|
This function will no longer use :meth:`~object.__int__`.
|
|
|
|
.. c:namespace:: NULL
|
|
|
|
.. c:function:: long PyLong_AS_LONG(PyObject *obj)
|
|
|
|
A :term:`soft deprecated` alias.
|
|
Exactly equivalent to the preferred ``PyLong_AsLong``. In particular,
|
|
it can fail with :exc:`OverflowError` or another exception.
|
|
|
|
.. deprecated:: 3.14
|
|
The function is soft deprecated.
|
|
|
|
.. c:function:: int PyLong_AsInt(PyObject *obj)
|
|
|
|
Similar to :c:func:`PyLong_AsLong`, but store the result in a C
|
|
:c:expr:`int` instead of a C :c:expr:`long`.
|
|
|
|
.. versionadded:: 3.13
|
|
|
|
|
|
.. c:function:: long PyLong_AsLongAndOverflow(PyObject *obj, int *overflow)
|
|
|
|
Return a C :c:expr:`long` representation of *obj*. If *obj* is not an
|
|
instance of :c:type:`PyLongObject`, first call its :meth:`~object.__index__`
|
|
method (if present) to convert it to a :c:type:`PyLongObject`.
|
|
|
|
If the value of *obj* is greater than :c:macro:`LONG_MAX` or less than
|
|
:c:macro:`LONG_MIN`, set *\*overflow* to ``1`` or ``-1``, respectively, and
|
|
return ``-1``; otherwise, set *\*overflow* to ``0``. If any other exception
|
|
occurs set *\*overflow* to ``0`` and return ``-1`` as usual.
|
|
|
|
Returns ``-1`` on error. Use :c:func:`PyErr_Occurred` to disambiguate.
|
|
|
|
.. versionchanged:: 3.8
|
|
Use :meth:`~object.__index__` if available.
|
|
|
|
.. versionchanged:: 3.10
|
|
This function will no longer use :meth:`~object.__int__`.
|
|
|
|
|
|
.. c:function:: long long PyLong_AsLongLong(PyObject *obj)
|
|
|
|
.. index::
|
|
single: OverflowError (built-in exception)
|
|
|
|
Return a C :c:expr:`long long` representation of *obj*. If *obj* is not an
|
|
instance of :c:type:`PyLongObject`, first call its :meth:`~object.__index__` method
|
|
(if present) to convert it to a :c:type:`PyLongObject`.
|
|
|
|
Raise :exc:`OverflowError` if the value of *obj* is out of range for a
|
|
:c:expr:`long long`.
|
|
|
|
Returns ``-1`` on error. Use :c:func:`PyErr_Occurred` to disambiguate.
|
|
|
|
.. versionchanged:: 3.8
|
|
Use :meth:`~object.__index__` if available.
|
|
|
|
.. versionchanged:: 3.10
|
|
This function will no longer use :meth:`~object.__int__`.
|
|
|
|
|
|
.. c:function:: long long PyLong_AsLongLongAndOverflow(PyObject *obj, int *overflow)
|
|
|
|
Return a C :c:expr:`long long` representation of *obj*. If *obj* is not an
|
|
instance of :c:type:`PyLongObject`, first call its :meth:`~object.__index__` method
|
|
(if present) to convert it to a :c:type:`PyLongObject`.
|
|
|
|
If the value of *obj* is greater than :c:macro:`LLONG_MAX` or less than
|
|
:c:macro:`LLONG_MIN`, set *\*overflow* to ``1`` or ``-1``, respectively,
|
|
and return ``-1``; otherwise, set *\*overflow* to ``0``. If any other
|
|
exception occurs set *\*overflow* to ``0`` and return ``-1`` as usual.
|
|
|
|
Returns ``-1`` on error. Use :c:func:`PyErr_Occurred` to disambiguate.
|
|
|
|
.. versionadded:: 3.2
|
|
|
|
.. versionchanged:: 3.8
|
|
Use :meth:`~object.__index__` if available.
|
|
|
|
.. versionchanged:: 3.10
|
|
This function will no longer use :meth:`~object.__int__`.
|
|
|
|
|
|
.. c:function:: Py_ssize_t PyLong_AsSsize_t(PyObject *pylong)
|
|
|
|
.. index::
|
|
single: PY_SSIZE_T_MAX (C macro)
|
|
single: OverflowError (built-in exception)
|
|
|
|
Return a C :c:type:`Py_ssize_t` representation of *pylong*. *pylong* must
|
|
be an instance of :c:type:`PyLongObject`.
|
|
|
|
Raise :exc:`OverflowError` if the value of *pylong* is out of range for a
|
|
:c:type:`Py_ssize_t`.
|
|
|
|
Returns ``-1`` on error. Use :c:func:`PyErr_Occurred` to disambiguate.
|
|
|
|
|
|
.. c:function:: unsigned long PyLong_AsUnsignedLong(PyObject *pylong)
|
|
|
|
.. index::
|
|
single: ULONG_MAX (C macro)
|
|
single: OverflowError (built-in exception)
|
|
|
|
Return a C :c:expr:`unsigned long` representation of *pylong*. *pylong*
|
|
must be an instance of :c:type:`PyLongObject`.
|
|
|
|
Raise :exc:`OverflowError` if the value of *pylong* is out of range for a
|
|
:c:expr:`unsigned long`.
|
|
|
|
Returns ``(unsigned long)-1`` on error.
|
|
Use :c:func:`PyErr_Occurred` to disambiguate.
|
|
|
|
|
|
.. c:function:: size_t PyLong_AsSize_t(PyObject *pylong)
|
|
|
|
.. index::
|
|
single: SIZE_MAX (C macro)
|
|
single: OverflowError (built-in exception)
|
|
|
|
Return a C :c:type:`size_t` representation of *pylong*. *pylong* must be
|
|
an instance of :c:type:`PyLongObject`.
|
|
|
|
Raise :exc:`OverflowError` if the value of *pylong* is out of range for a
|
|
:c:type:`size_t`.
|
|
|
|
Returns ``(size_t)-1`` on error.
|
|
Use :c:func:`PyErr_Occurred` to disambiguate.
|
|
|
|
|
|
.. c:function:: unsigned long long PyLong_AsUnsignedLongLong(PyObject *pylong)
|
|
|
|
.. index::
|
|
single: OverflowError (built-in exception)
|
|
|
|
Return a C :c:expr:`unsigned long long` representation of *pylong*. *pylong*
|
|
must be an instance of :c:type:`PyLongObject`.
|
|
|
|
Raise :exc:`OverflowError` if the value of *pylong* is out of range for an
|
|
:c:expr:`unsigned long long`.
|
|
|
|
Returns ``(unsigned long long)-1`` on error.
|
|
Use :c:func:`PyErr_Occurred` to disambiguate.
|
|
|
|
.. versionchanged:: 3.1
|
|
A negative *pylong* now raises :exc:`OverflowError`, not :exc:`TypeError`.
|
|
|
|
|
|
.. c:function:: unsigned long PyLong_AsUnsignedLongMask(PyObject *obj)
|
|
|
|
Return a C :c:expr:`unsigned long` representation of *obj*. If *obj* is not
|
|
an instance of :c:type:`PyLongObject`, first call its :meth:`~object.__index__`
|
|
method (if present) to convert it to a :c:type:`PyLongObject`.
|
|
|
|
If the value of *obj* is out of range for an :c:expr:`unsigned long`,
|
|
return the reduction of that value modulo ``ULONG_MAX + 1``.
|
|
|
|
Returns ``(unsigned long)-1`` on error. Use :c:func:`PyErr_Occurred` to
|
|
disambiguate.
|
|
|
|
.. versionchanged:: 3.8
|
|
Use :meth:`~object.__index__` if available.
|
|
|
|
.. versionchanged:: 3.10
|
|
This function will no longer use :meth:`~object.__int__`.
|
|
|
|
|
|
.. c:function:: unsigned long long PyLong_AsUnsignedLongLongMask(PyObject *obj)
|
|
|
|
Return a C :c:expr:`unsigned long long` representation of *obj*. If *obj*
|
|
is not an instance of :c:type:`PyLongObject`, first call its
|
|
:meth:`~object.__index__` method (if present) to convert it to a
|
|
:c:type:`PyLongObject`.
|
|
|
|
If the value of *obj* is out of range for an :c:expr:`unsigned long long`,
|
|
return the reduction of that value modulo ``ULLONG_MAX + 1``.
|
|
|
|
Returns ``(unsigned long long)-1`` on error. Use :c:func:`PyErr_Occurred`
|
|
to disambiguate.
|
|
|
|
.. versionchanged:: 3.8
|
|
Use :meth:`~object.__index__` if available.
|
|
|
|
.. versionchanged:: 3.10
|
|
This function will no longer use :meth:`~object.__int__`.
|
|
|
|
|
|
.. c:function:: int PyLong_AsInt32(PyObject *obj, int32_t *value)
|
|
int PyLong_AsInt64(PyObject *obj, int64_t *value)
|
|
|
|
Set *\*value* to a signed C :c:expr:`int32_t` or :c:expr:`int64_t`
|
|
representation of *obj*.
|
|
|
|
If the *obj* value is out of range, raise an :exc:`OverflowError`.
|
|
|
|
Set *\*value* and return ``0`` on success.
|
|
Set an exception and return ``-1`` on error.
|
|
|
|
*value* must not be ``NULL``.
|
|
|
|
.. versionadded:: 3.14
|
|
|
|
|
|
.. c:function:: int PyLong_AsUInt32(PyObject *obj, uint32_t *value)
|
|
int PyLong_AsUInt64(PyObject *obj, uint64_t *value)
|
|
|
|
Set *\*value* to an unsigned C :c:expr:`uint32_t` or :c:expr:`uint64_t`
|
|
representation of *obj*.
|
|
|
|
If *obj* is not an instance of :c:type:`PyLongObject`, first call its
|
|
:meth:`~object.__index__` method (if present) to convert it to a
|
|
:c:type:`PyLongObject`.
|
|
|
|
* If *obj* is negative, raise a :exc:`ValueError`.
|
|
* If the *obj* value is out of range, raise an :exc:`OverflowError`.
|
|
|
|
Set *\*value* and return ``0`` on success.
|
|
Set an exception and return ``-1`` on error.
|
|
|
|
*value* must not be ``NULL``.
|
|
|
|
.. versionadded:: 3.14
|
|
|
|
|
|
.. c:function:: double PyLong_AsDouble(PyObject *pylong)
|
|
|
|
Return a C :c:expr:`double` representation of *pylong*. *pylong* must be
|
|
an instance of :c:type:`PyLongObject`.
|
|
|
|
Raise :exc:`OverflowError` if the value of *pylong* is out of range for a
|
|
:c:expr:`double`.
|
|
|
|
Returns ``-1.0`` on error. Use :c:func:`PyErr_Occurred` to disambiguate.
|
|
|
|
|
|
.. c:function:: void* PyLong_AsVoidPtr(PyObject *pylong)
|
|
|
|
Convert a Python integer *pylong* to a C :c:expr:`void` pointer.
|
|
If *pylong* cannot be converted, an :exc:`OverflowError` will be raised. This
|
|
is only assured to produce a usable :c:expr:`void` pointer for values created
|
|
with :c:func:`PyLong_FromVoidPtr`.
|
|
|
|
Returns ``NULL`` on error. Use :c:func:`PyErr_Occurred` to disambiguate.
|
|
|
|
|
|
.. c:function:: Py_ssize_t PyLong_AsNativeBytes(PyObject *pylong, void* buffer, Py_ssize_t n_bytes, int flags)
|
|
|
|
Copy the Python integer value *pylong* to a native *buffer* of size
|
|
*n_bytes*. The *flags* can be set to ``-1`` to behave similarly to a C cast,
|
|
or to values documented below to control the behavior.
|
|
|
|
Returns ``-1`` with an exception raised on error. This may happen if
|
|
*pylong* cannot be interpreted as an integer, or if *pylong* was negative
|
|
and the ``Py_ASNATIVEBYTES_REJECT_NEGATIVE`` flag was set.
|
|
|
|
Otherwise, returns the number of bytes required to store the value.
|
|
If this is equal to or less than *n_bytes*, the entire value was copied.
|
|
All *n_bytes* of the buffer are written: large buffers are padded with
|
|
zeroes.
|
|
|
|
If the returned value is greater than than *n_bytes*, the value was
|
|
truncated: as many of the lowest bits of the value as could fit are written,
|
|
and the higher bits are ignored. This matches the typical behavior
|
|
of a C-style downcast.
|
|
|
|
.. note::
|
|
|
|
Overflow is not considered an error. If the returned value
|
|
is larger than *n_bytes*, most significant bits were discarded.
|
|
|
|
``0`` will never be returned.
|
|
|
|
Values are always copied as two's-complement.
|
|
|
|
Usage example::
|
|
|
|
int32_t value;
|
|
Py_ssize_t bytes = PyLong_AsNativeBytes(pylong, &value, sizeof(value), -1);
|
|
if (bytes < 0) {
|
|
// Failed. A Python exception was set with the reason.
|
|
return NULL;
|
|
}
|
|
else if (bytes <= (Py_ssize_t)sizeof(value)) {
|
|
// Success!
|
|
}
|
|
else {
|
|
// Overflow occurred, but 'value' contains the truncated
|
|
// lowest bits of pylong.
|
|
}
|
|
|
|
Passing zero to *n_bytes* will return the size of a buffer that would
|
|
be large enough to hold the value. This may be larger than technically
|
|
necessary, but not unreasonably so. If *n_bytes=0*, *buffer* may be
|
|
``NULL``.
|
|
|
|
.. note::
|
|
|
|
Passing *n_bytes=0* to this function is not an accurate way to determine
|
|
the bit length of the value.
|
|
|
|
To get at the entire Python value of an unknown size, the function can be
|
|
called twice: first to determine the buffer size, then to fill it::
|
|
|
|
// Ask how much space we need.
|
|
Py_ssize_t expected = PyLong_AsNativeBytes(pylong, NULL, 0, -1);
|
|
if (expected < 0) {
|
|
// Failed. A Python exception was set with the reason.
|
|
return NULL;
|
|
}
|
|
assert(expected != 0); // Impossible per the API definition.
|
|
uint8_t *bignum = malloc(expected);
|
|
if (!bignum) {
|
|
PyErr_SetString(PyExc_MemoryError, "bignum malloc failed.");
|
|
return NULL;
|
|
}
|
|
// Safely get the entire value.
|
|
Py_ssize_t bytes = PyLong_AsNativeBytes(pylong, bignum, expected, -1);
|
|
if (bytes < 0) { // Exception has been set.
|
|
free(bignum);
|
|
return NULL;
|
|
}
|
|
else if (bytes > expected) { // This should not be possible.
|
|
PyErr_SetString(PyExc_RuntimeError,
|
|
"Unexpected bignum truncation after a size check.");
|
|
free(bignum);
|
|
return NULL;
|
|
}
|
|
// The expected success given the above pre-check.
|
|
// ... use bignum ...
|
|
free(bignum);
|
|
|
|
*flags* is either ``-1`` (``Py_ASNATIVEBYTES_DEFAULTS``) to select defaults
|
|
that behave most like a C cast, or a combintation of the other flags in
|
|
the table below.
|
|
Note that ``-1`` cannot be combined with other flags.
|
|
|
|
Currently, ``-1`` corresponds to
|
|
``Py_ASNATIVEBYTES_NATIVE_ENDIAN | Py_ASNATIVEBYTES_UNSIGNED_BUFFER``.
|
|
|
|
.. c:namespace:: NULL
|
|
|
|
============================================= ======
|
|
Flag Value
|
|
============================================= ======
|
|
.. c:macro:: Py_ASNATIVEBYTES_DEFAULTS ``-1``
|
|
.. c:macro:: Py_ASNATIVEBYTES_BIG_ENDIAN ``0``
|
|
.. c:macro:: Py_ASNATIVEBYTES_LITTLE_ENDIAN ``1``
|
|
.. c:macro:: Py_ASNATIVEBYTES_NATIVE_ENDIAN ``3``
|
|
.. c:macro:: Py_ASNATIVEBYTES_UNSIGNED_BUFFER ``4``
|
|
.. c:macro:: Py_ASNATIVEBYTES_REJECT_NEGATIVE ``8``
|
|
.. c:macro:: Py_ASNATIVEBYTES_ALLOW_INDEX ``16``
|
|
============================================= ======
|
|
|
|
Specifying ``Py_ASNATIVEBYTES_NATIVE_ENDIAN`` will override any other endian
|
|
flags. Passing ``2`` is reserved.
|
|
|
|
By default, sufficient buffer will be requested to include a sign bit.
|
|
For example, when converting 128 with *n_bytes=1*, the function will return
|
|
2 (or more) in order to store a zero sign bit.
|
|
|
|
If ``Py_ASNATIVEBYTES_UNSIGNED_BUFFER`` is specified, a zero sign bit
|
|
will be omitted from size calculations. This allows, for example, 128 to fit
|
|
in a single-byte buffer. If the destination buffer is later treated as
|
|
signed, a positive input value may become negative.
|
|
Note that the flag does not affect handling of negative values: for those,
|
|
space for a sign bit is always requested.
|
|
|
|
Specifying ``Py_ASNATIVEBYTES_REJECT_NEGATIVE`` causes an exception to be set
|
|
if *pylong* is negative. Without this flag, negative values will be copied
|
|
provided there is enough space for at least one sign bit, regardless of
|
|
whether ``Py_ASNATIVEBYTES_UNSIGNED_BUFFER`` was specified.
|
|
|
|
If ``Py_ASNATIVEBYTES_ALLOW_INDEX`` is specified and a non-integer value is
|
|
passed, its :meth:`~object.__index__` method will be called first. This may
|
|
result in Python code executing and other threads being allowed to run, which
|
|
could cause changes to other objects or values in use. When *flags* is
|
|
``-1``, this option is not set, and non-integer values will raise
|
|
:exc:`TypeError`.
|
|
|
|
.. note::
|
|
|
|
With the default *flags* (``-1``, or *UNSIGNED_BUFFER* without
|
|
*REJECT_NEGATIVE*), multiple Python integers can map to a single value
|
|
without overflow. For example, both ``255`` and ``-1`` fit a single-byte
|
|
buffer and set all its bits.
|
|
This matches typical C cast behavior.
|
|
|
|
.. versionadded:: 3.13
|
|
|
|
|
|
.. c:function:: int PyLong_GetSign(PyObject *obj, int *sign)
|
|
|
|
Get the sign of the integer object *obj*.
|
|
|
|
On success, set *\*sign* to the integer sign (0, -1 or +1 for zero, negative or
|
|
positive integer, respectively) and return 0.
|
|
|
|
On failure, return -1 with an exception set. This function always succeeds
|
|
if *obj* is a :c:type:`PyLongObject` or its subtype.
|
|
|
|
.. versionadded:: next
|
|
|
|
|
|
.. c:function:: PyObject* PyLong_GetInfo(void)
|
|
|
|
On success, return a read only :term:`named tuple`, that holds
|
|
information about Python's internal representation of integers.
|
|
See :data:`sys.int_info` for description of individual fields.
|
|
|
|
On failure, return ``NULL`` with an exception set.
|
|
|
|
.. versionadded:: 3.1
|
|
|
|
|
|
.. c:function:: int PyUnstable_Long_IsCompact(const PyLongObject* op)
|
|
|
|
Return 1 if *op* is compact, 0 otherwise.
|
|
|
|
This function makes it possible for performance-critical code to implement
|
|
a “fast path” for small integers. For compact values use
|
|
:c:func:`PyUnstable_Long_CompactValue`; for others fall back to a
|
|
:c:func:`PyLong_As* <PyLong_AsSize_t>` function or
|
|
:c:func:`PyLong_AsNativeBytes`.
|
|
|
|
The speedup is expected to be negligible for most users.
|
|
|
|
Exactly what values are considered compact is an implementation detail
|
|
and is subject to change.
|
|
|
|
.. c:function:: Py_ssize_t PyUnstable_Long_CompactValue(const PyLongObject* op)
|
|
|
|
If *op* is compact, as determined by :c:func:`PyUnstable_Long_IsCompact`,
|
|
return its value.
|
|
|
|
Otherwise, the return value is undefined.
|
|
|