bpo-38629: implement __floor__ and __ceil__ for float type (GH-16985)

diff --git a/Objects/clinic/floatobject.c.h b/Objects/clinic/floatobject.c.h
index b684ba0..b755483 100644
--- a/Objects/clinic/floatobject.c.h
+++ b/Objects/clinic/floatobject.c.h
@@ -38,6 +38,42 @@
     return float___trunc___impl(self);
 }
 
+PyDoc_STRVAR(float___floor____doc__,
+"__floor__($self, /)\n"
+"--\n"
+"\n"
+"Return the floor as an Integral.");
+
+#define FLOAT___FLOOR___METHODDEF    \
+    {"__floor__", (PyCFunction)float___floor__, METH_NOARGS, float___floor____doc__},
+
+static PyObject *
+float___floor___impl(PyObject *self);
+
+static PyObject *
+float___floor__(PyObject *self, PyObject *Py_UNUSED(ignored))
+{
+    return float___floor___impl(self);
+}
+
+PyDoc_STRVAR(float___ceil____doc__,
+"__ceil__($self, /)\n"
+"--\n"
+"\n"
+"Return the ceiling as an Integral.");
+
+#define FLOAT___CEIL___METHODDEF    \
+    {"__ceil__", (PyCFunction)float___ceil__, METH_NOARGS, float___ceil____doc__},
+
+static PyObject *
+float___ceil___impl(PyObject *self);
+
+static PyObject *
+float___ceil__(PyObject *self, PyObject *Py_UNUSED(ignored))
+{
+    return float___ceil___impl(self);
+}
+
 PyDoc_STRVAR(float___round____doc__,
 "__round__($self, ndigits=None, /)\n"
 "--\n"
@@ -351,4 +387,4 @@
 exit:
     return return_value;
 }
-/*[clinic end generated code: output=1676433b9f04fbc9 input=a9049054013a1b77]*/
+/*[clinic end generated code: output=25fbbe253f44e2df input=a9049054013a1b77]*/
diff --git a/Objects/floatobject.c b/Objects/floatobject.c
index 20a5155..4fc412b 100644
--- a/Objects/floatobject.c
+++ b/Objects/floatobject.c
@@ -905,6 +905,34 @@
     return PyLong_FromDouble(wholepart);
 }
 
+/*[clinic input]
+float.__floor__
+
+Return the floor as an Integral.
+[clinic start generated code]*/
+
+static PyObject *
+float___floor___impl(PyObject *self)
+/*[clinic end generated code: output=e0551dbaea8c01d1 input=77bb13eb12e268df]*/
+{
+    double x = PyFloat_AS_DOUBLE(self);
+    return PyLong_FromDouble(floor(x));
+}
+
+/*[clinic input]
+float.__ceil__
+
+Return the ceiling as an Integral.
+[clinic start generated code]*/
+
+static PyObject *
+float___ceil___impl(PyObject *self)
+/*[clinic end generated code: output=a2fd8858f73736f9 input=79e41ae94aa0a516]*/
+{
+    double x = PyFloat_AS_DOUBLE(self);
+    return PyLong_FromDouble(ceil(x));
+}
+
 /* double_round: rounds a finite double to the closest multiple of
    10**-ndigits; here ndigits is within reasonable bounds (typically, -308 <=
    ndigits <= 323).  Returns a Python float, or sets a Python error and
@@ -1828,6 +1856,8 @@
 static PyMethodDef float_methods[] = {
     FLOAT_CONJUGATE_METHODDEF
     FLOAT___TRUNC___METHODDEF
+    FLOAT___FLOOR___METHODDEF
+    FLOAT___CEIL___METHODDEF
     FLOAT___ROUND___METHODDEF
     FLOAT_AS_INTEGER_RATIO_METHODDEF
     FLOAT_FROMHEX_METHODDEF