Add PyFloat_Pack8() (#26)

Author: vstinner

docs/api.rst

@@ -39,6 +39,42 @@ Python 3.11
 
    Not available on PyPy
 
+.. c:function:: int PyFloat_Pack2(double x, unsigned char *p, int le)
+
+   Pack a C double as the IEEE 754 binary16 half-precision format.
+
+   Availability: Python 3.6 and newer. Not available on PyPy
+
+.. c:function:: int PyFloat_Pack4(double x, unsigned char *p, int le)
+
+   Pack a C double as the IEEE 754 binary32 single precision format.
+
+   Not available on PyPy
+
+.. c:function:: int PyFloat_Pack8(double x, unsigned char *p, int le)
+
+   Pack a C double as the IEEE 754 binary64 double precision format.
+
+   Not available on PyPy
+
+.. c:function:: double PyFloat_Unpack2(const unsigned char *p, int le)
+
+   Unpack the IEEE 754 binary16 half-precision format as a C double.
+
+   Availability: Python 3.6 and newer. Not available on PyPy
+
+.. c:function:: double PyFloat_Unpack4(const unsigned char *p, int le)
+
+   Unpack the IEEE 754 binary32 single precision format as a C double.
+
+   Not available on PyPy
+
+.. c:function:: double PyFloat_Unpack8(const unsigned char *p, int le)
+
+   Unpack the IEEE 754 binary64 double precision format as a C double.
+
+   Not available on PyPy
+
 Python 3.10
 -----------
 

docs/changelog.rst

@@ -1,6 +1,9 @@
 Changelog
 =========
 
+* 2022-03-12: Add functions ``PyFloat_Pack2()``, ``PyFloat_Pack4()``,
+  ``PyFloat_Pack8()``, ``PyFloat_Unpack2()``, ``PyFloat_Unpack4()`` and
+  ``PyFloat_Unpack8()``.
 * 2022-03-03: The project moved to https://github.com/python/pythoncapi_compat
 * 2022-02-11: The project license changes from the MIT license to the Zero
   Clause BSD (0BSD) license. Projects copying ``pythoncapi_compat.h`` no longer

pythoncapi_compat.h

@@ -391,6 +391,45 @@ _Py_IS_TYPE(const PyObject *ob, const PyTypeObject *type) {
 #endif
 
 
+// bpo-46906 added PyFloat_Pack2() and PyFloat_Unpack2() to Python 3.11a7.
+// bpo-11734 added _PyFloat_Pack2() and _PyFloat_Unpack2() to Python 3.6.0b1.
+// Python 3.11a2 moved _PyFloat_Pack2() and _PyFloat_Unpack2() to the internal
+// C API: Python 3.11a2-3.11a6 versions are not supported.
+#if 0x030600B1 <= PY_VERSION_HEX && PY_VERSION_HEX <= 0x030B00A1 && !defined(PYPY_VERSION)
+PYCAPI_COMPAT_STATIC_INLINE(int)
+PyFloat_Pack2(double x, char *p, int le)
+{ return _PyFloat_Pack2(x, (unsigned char*)p, le); }
+
+PYCAPI_COMPAT_STATIC_INLINE(double)
+PyFloat_Unpack2(const char *p, int le)
+{ return _PyFloat_Unpack2((const unsigned char *)p, le); }
+#endif
+
+
+// bpo-46906 added PyFloat_Pack4(), PyFloat_Pack8(), PyFloat_Unpack4() and
+// PyFloat_Unpack8() to Python 3.11a7.
+// Python 3.11a2 moved _PyFloat_Pack4(), _PyFloat_Pack8(), _PyFloat_Unpack4()
+// and _PyFloat_Unpack8() to the internal C API: Python 3.11a2-3.11a6 versions
+// are not supported.
+#if PY_VERSION_HEX <= 0x030B00A1 && !defined(PYPY_VERSION)
+PYCAPI_COMPAT_STATIC_INLINE(int)
+PyFloat_Pack4(double x, char *p, int le)
+{ return _PyFloat_Pack4(x, (unsigned char*)p, le); }
+
+PYCAPI_COMPAT_STATIC_INLINE(int)
+PyFloat_Pack8(double x, char *p, int le)
+{ return _PyFloat_Pack8(x, (unsigned char*)p, le); }
+
+PYCAPI_COMPAT_STATIC_INLINE(double)
+PyFloat_Unpack4(const char *p, int le)
+{ return _PyFloat_Unpack4((const unsigned char *)p, le); }
+
+PYCAPI_COMPAT_STATIC_INLINE(double)
+PyFloat_Unpack8(const char *p, int le)
+{ return _PyFloat_Unpack8((const unsigned char *)p, le); }
+#endif
+
+
 // Py_UNUSED() was added to Python 3.4.0b2.
 #if PY_VERSION_HEX < 0x030400B2 && !defined(Py_UNUSED)
 #  if defined(__GNUC__) || defined(__clang__)

tests/test_pythoncapi_compat_cext.c

@@ -406,6 +406,62 @@ test_module(PyObject *Py_UNUSED(module), PyObject* Py_UNUSED(ignored))
 }
 
 
+#if (PY_VERSION_HEX <= 0x030B00A1 || 0x030B00A7 <= PY_VERSION_HEX) && !defined(PYPY_VERSION)
+static PyObject *
+test_float_pack(PyObject *Py_UNUSED(module), PyObject* Py_UNUSED(ignored))
+{
+    const int big_endian = 0;
+    const int little_endian = 1;
+    char data[8];
+    const double d = 1.5;
+
+#if PY_VERSION_HEX >= 0x030600B1
+#  define HAVE_FLOAT_PACK2
+#endif
+
+    // Test Pack (big endian)
+#ifdef HAVE_FLOAT_PACK2
+    assert(PyFloat_Pack2(d, data, big_endian) == 0);
+    assert(memcmp(data, ">\x00", 2) == 0);
+#endif
+
+    assert(PyFloat_Pack4(d, data, big_endian) == 0);
+    assert(memcmp(data, "?\xc0\x00\x00", 2) == 0);
+
+    assert(PyFloat_Pack8(d, data, big_endian) == 0);
+    assert(memcmp(data, "?\xf8\x00\x00\x00\x00\x00\x00", 2) == 0);
+
+    // Test Pack (little endian)
+#ifdef HAVE_FLOAT_PACK2
+    assert(PyFloat_Pack2(d, data, little_endian) == 0);
+    assert(memcmp(data, "\x00>", 2) == 0);
+#endif
+
+    assert(PyFloat_Pack4(d, data, little_endian) == 0);
+    assert(memcmp(data, "\x00\x00\xc0?", 2) == 0);
+
+    assert(PyFloat_Pack8(d, data, little_endian) == 0);
+    assert(memcmp(data, "\x00\x00\x00\x00\x00\x00\xf8?", 2) == 0);
+
+    // Test Unpack (big endian)
+#ifdef HAVE_FLOAT_PACK2
+    assert(PyFloat_Unpack2(">\x00", big_endian) == d);
+#endif
+    assert(PyFloat_Unpack4("?\xc0\x00\x00", big_endian) == d);
+    assert(PyFloat_Unpack8("?\xf8\x00\x00\x00\x00\x00\x00", big_endian) == d);
+
+    // Test Unpack (little endian)
+#ifdef HAVE_FLOAT_PACK2
+    assert(PyFloat_Unpack2("\x00>", little_endian) == d);
+#endif
+    assert(PyFloat_Unpack4("\x00\x00\xc0?", little_endian) == d);
+    assert(PyFloat_Unpack8("\x00\x00\x00\x00\x00\x00\xf8?", little_endian) == d);
+
+    Py_RETURN_NONE;
+}
+#endif
+
+
 static struct PyMethodDef methods[] = {
     {"test_object", test_object, METH_NOARGS, NULL},
     {"test_py_is", test_py_is, METH_NOARGS, NULL},
@@ -418,6 +474,9 @@ static struct PyMethodDef methods[] = {
     {"test_calls", test_calls, METH_NOARGS, NULL},
     {"test_gc", test_gc, METH_NOARGS, NULL},
     {"test_module", test_module, METH_NOARGS, NULL},
+#if (PY_VERSION_HEX <= 0x030B00A1 || 0x030B00A7 <= PY_VERSION_HEX) && !defined(PYPY_VERSION)
+    {"test_float_pack", test_float_pack, METH_NOARGS, NULL},
+#endif
     {NULL, NULL, 0, NULL}
 };