3 files changed, 102 insertions, 0 deletions
diff --git a/numpy/core/setup.py b/numpy/core/setup.py
index 6df82b3fa..b99f1853d 100644
--- a/numpy/core/setup.py
+++ b/numpy/core/setup.py
@@ -935,6 +935,13 @@ def configuration(parent_package='',top_path=None):
     config.add_extension('multiarray_tests',
                     sources = [join('src', 'multiarray', 'multiarray_tests.c.src')])
 
+    #######################################################################
+    #                        operand_flag_tests module                           #
+    #######################################################################
+
+    config.add_extension('operand_flag_tests',
+                    sources = [join('src','umath', 'operand_flag_tests.c.src')])
+
     config.add_data_dir('tests')
     config.add_data_dir('tests/data')
 
diff --git a/numpy/core/src/umath/operand_flag_tests.c.src b/numpy/core/src/umath/operand_flag_tests.c.src
new file mode 100644
index 000000000..dae309683
--- /dev/null
+++ b/numpy/core/src/umath/operand_flag_tests.c.src
@@ -0,0 +1,87 @@
+#define NPY_NO_DEPRECATED_API NPY_API_VERSION
+
+#include <stdint.h>
+#include <math.h>
+#include <Python.h>
+#include <structmember.h>
+#include <numpy/arrayobject.h>
+#include <numpy/ufuncobject.h>
+#include "numpy/npy_3kcompat.h"
+
+
+static PyMethodDef TestMethods[] = {
+        {NULL, NULL, 0, NULL}
+};
+
+
+static void
+inplace_add(char **args, npy_intp *dimensions, npy_intp *steps, void *data)
+{
+    npy_intp i;
+    npy_intp n = dimensions[0];
+    char *in1 = args[0];
+    char *in2 = args[1];
+    npy_intp in1_step = steps[0];
+    npy_intp in2_step = steps[1];
+
+    for (i = 0; i < n; i++) {
+        (*(long *)in1) = *(long*)in1 + *(long*)in2;
+        in1 += in1_step;
+        in2 += in2_step;
+    }
+}
+
+
+/*This a pointer to the above function*/
+PyUFuncGenericFunction funcs[1] = {&inplace_add};
+
+/* These are the input and return dtypes of logit.*/
+static char types[2] = {NPY_LONG, NPY_LONG};
+
+static void *data[1] = {NULL};
+
+#if defined(NPY_PY3K)
+static struct PyModuleDef moduledef = {
+    PyModuleDef_HEAD_INIT,
+    "operand_flag_tests",
+    NULL,
+    -1,
+    TestMethods,
+    NULL,
+    NULL,
+    NULL,
+    NULL
+};
+
+PyObject *PyInit_operand_flag_tests(void)
+{
+#else
+PyMODINIT_FUNC initoperand_flag_tests(void)
+{
+#endif
+    PyObject *m, *ufunc;
+
+#if defined(NPY_PY3K)
+    m = PyModule_Create(&moduledef);
+#else
+    m = Py_InitModule("operand_flag_tests", TestMethods);
+#endif
+    if (m == NULL) {
+        return;
+    }
+
+    import_array();
+    import_umath();
+
+    ufunc = PyUFunc_FromFuncAndData(funcs, data, types, 1, 2, 0,
+                                    PyUFunc_None, "inplace_add",
+                                    "inplace_add_docstring", 0);
+
+    /* Set flags to turn off buffering for first input operand,
+       so that result can be written back to input operand. */
+    ((PyUFuncObject*)ufunc)->op_flags[0] = NPY_ITER_READWRITE;
+    ((PyUFuncObject*)ufunc)->iter_flags = NPY_ITER_REDUCE_OK;
+    PyModule_AddObject(m, "inplace_add", (PyObject*)ufunc);
+
+    return m;
+}
diff --git a/numpy/core/tests/test_ufunc.py b/numpy/core/tests/test_ufunc.py
index dbbd15397..c969fa8ac 100644
--- a/numpy/core/tests/test_ufunc.py
+++ b/numpy/core/tests/test_ufunc.py
@@ -5,6 +5,7 @@ import sys
 import numpy as np
 from numpy.testing import *
 import numpy.core.umath_tests as umt
+import numpy.core.operand_flag_tests as opflag_tests
 from numpy.compat import asbytes
 from numpy.core.test_rational import *
 
@@ -786,6 +787,13 @@ class TestUfunc(TestCase):
 
         # no output type should raise TypeError
         assert_raises(TypeError, test_add, a, b)
+    
+    def test_operand_flags(self):
+        a = np.arange(16, dtype='i8').reshape(4,4)
+        b = np.arange(9, dtype='i8').reshape(3,3)
+        opflag_tests.inplace_add(a[:-1,:-1], b)
+        assert_equal(a, np.array([[0,2,4,3],[7,9,11,7],
+            [14,16,18,11],[12,13,14,15]], dtype='i8'))
 
 if __name__ == "__main__":
     run_module_suite()