[3.15] gh-141004: Document missing pyport.h macros (GH-159719) (GH-159795)

(cherry picked from commit 4c34b7e)

Co-authored-by: Peter Bierma <zintensitydev@gmail.com>

Author: miss-islington

Doc/c-api/float.rst

@@ -214,7 +214,7 @@ Pack functions
 The pack routines write 2, 4 or 8 bytes, starting at *p*. *le* is an
 :c:expr:`int` argument, non-zero if you want the bytes string in little-endian
 format (exponent last, at ``p+1``, ``p+3``, or ``p+6`` and ``p+7``), zero if you
-want big-endian format (exponent first, at *p*). Use the :c:macro:`!PY_LITTLE_ENDIAN`
+want big-endian format (exponent first, at *p*). Use the :c:macro:`PY_LITTLE_ENDIAN`
 constant to select the native endian: it is equal to ``0`` on big
 endian processor, or ``1`` on little endian processor.
 
@@ -240,7 +240,7 @@ Unpack functions
 The unpack routines read 2, 4 or 8 bytes, starting at *p*.  *le* is an
 :c:expr:`int` argument, non-zero if the bytes string is in little-endian format
 (exponent last, at ``p+1``, ``p+3`` or ``p+6`` and ``p+7``), zero if big-endian
-(exponent first, at *p*). Use the :c:macro:`!PY_LITTLE_ENDIAN` constant to
+(exponent first, at *p*). Use the :c:macro:`PY_LITTLE_ENDIAN` constant to
 select the native endian: it is equal to ``0`` on big endian processor, or ``1``
 on little endian processor.
 

Doc/c-api/intro.rst

@@ -299,6 +299,12 @@ Numeric utilities
    Argument must be a character or an integer in the range [-128, 127] or [0,
    255].  This macro returns ``c`` cast to an ``unsigned char``.
 
+.. c:macro:: PY_BIG_ENDIAN
+             PY_LITTLE_ENDIAN
+
+   Constants describing the byte order of the platform that Python was built
+   for. Exactly one of them is ``1`` and the other is ``0``.
+
 
 Assertion utilities
 ^^^^^^^^^^^^^^^^^^^
@@ -916,8 +922,13 @@ use them.
 
    A signed integral type such that ``sizeof(Py_ssize_t) == sizeof(size_t)``.
    C99 doesn't define such a thing directly (size_t is an unsigned integral type).
-   See :pep:`353` for details. ``PY_SSIZE_T_MAX`` is the largest positive value
-   of type :c:type:`Py_ssize_t`.
+   See :pep:`353` for details.
+
+.. c:macro:: PY_SSIZE_T_MAX
+             PY_SSIZE_T_MIN
+
+   The limit values (largest positive one and smallest negative one,
+   respecitvely) of type :c:type:`Py_ssize_t`.
 
 
 .. _api-exceptions:

Tools/check-c-api-docs/ignored_c_api.txt

@@ -26,7 +26,6 @@ PyExpat_CAPSULE_NAME
 # pyport.h
 PYLONG_BITS_IN_DIGIT
 PY_DWORD_MAX
-PY_BIG_ENDIAN
 # cpython/methodobject.h
 PyCFunction_GET_CLASS
 # cpython/descrobject.h