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vstinner merged 10 commits into from
Mar 19, 2026
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gh-145633: Refine notes on non-IEEE platforms #145845

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70f72fb
gh-145633: amend dae85c4d939 (refine notes on non-IEEE platforms)
skirpichev Mar 12, 2026
11e9292
-PY_LITTLE_ENDIAN from ignored_c_api.txt
skirpichev Mar 12, 2026
14f9f5c
+1
skirpichev Mar 12, 2026
9124afb
+ changes from #140989
skirpichev Mar 13, 2026
c525e92
-Doc/c-api/float.rst
skirpichev Mar 13, 2026
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skirpichev Mar 13, 2026
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skirpichev Mar 13, 2026
ad92de9
address review: move impl-detail note
skirpichev Mar 15, 2026
49a1e8e
Merge branch 'main' into dae85c4d939-amend-docs
skirpichev Mar 16, 2026
d8d6680
Update Doc/c-api/float.rst
vstinner Mar 19, 2026
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Co-authored-by: Stan Ulbrych <89152624+StanFromIreland@users.noreply.github.com>
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@skirpichev @StanFromIreland
skirpichev and StanFromIreland authored Mar 13, 2026
commit 83b7adb1307c2b302fbabeb6335cb72d7ae0149b
9 changes: 4 additions & 5 deletions Doc/c-api/float.rst
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Expand Up @@ -198,16 +198,15 @@ is the IEEE 754 binary64 double precision format, although the NaN type may
not be preserved on some platforms while unpacking (signaling NaNs become quiet
NaNs), for example on x86 systems in 32-bit mode.

It's assumed, that the :c:expr:`double` type has the IEEE 754 binary64 double
It's assumed that the :c:expr:`double` type has the IEEE 754 binary64 double
precision format. What happens if it's not true is partly accidental (alas).
On non-IEEE platforms with more precision, or larger dynamic range, than IEEE
754 supports, not all values can be packed; on non-IEEE platforms with less
precision, or smaller dynamic range, not all values can be unpacked. The
packing of special numbers like INFs and NaNs (if such things exist on the
platform) may be not handled correctly, and attempting to unpack a bytes string
platform) may not be handled correctly, and attempting to unpack a bytes string
containing an IEEE INF or NaN may raise an exception.

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.. versionadded:: 3.11

Pack functions
Expand All @@ -224,7 +223,7 @@ Return value: ``0`` if all is OK, ``-1`` if error (and an exception is set,
most likely :exc:`OverflowError`).

.. impl-detail::
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The :c:func:`PyFloat_Pack8` function always succeeds in the CPython.
The :c:func:`PyFloat_Pack8` function always succeeds in CPython.

.. c:function:: int PyFloat_Pack2(double x, char *p, int le)

Expand Down Expand Up @@ -254,7 +253,7 @@ Return value: The unpacked double. On error, this is ``-1.0`` and
:exc:`OverflowError`).

.. impl-detail::
These functions always succeed in the CPython.
These functions always succeed in CPython.

.. c:function:: double PyFloat_Unpack2(const char *p, int le)

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