calloc_sdram for clearing and allocating SDRAM

nengo_spinnaker/utils/machine_control.py

@@ -43,3 +43,19 @@ def test_and_boot(controller, hostname, machine_width, machine_height):
     logger.info(
         "Board is booted with {} v{:.2f}".format(sver.version_string,
                                                  sver.version))
+
+
+def calloc_sdram(controller, size, **kwargs):
+    """Allocate and clear a region of SDRAM.
+
+    Returns
+    -------
+    int
+        Address of the cleared and allocated space in SDRAM.
+    """
+    # Allocate the region in SDRAM, store the start address and clear the
+    # memory.
+    mem = controller.sdram_alloc_as_filelike(size, **kwargs)
+    addr = mem.address
+    mem.write(b'\x00' * size)
+    return addr

tests/utils/test_machine_control.py

@@ -7,6 +7,24 @@
 from nengo_spinnaker.utils import machine_control
 
 
+@pytest.mark.parametrize("n_bytes", [100, 123])
+def test_calloc_sdram(n_bytes):
+    """Test allocating and zeroing a region of SDRAM."""
+    # Create a mock machine controller
+    cn = mock.Mock()
+    mem = cn.sdram_alloc_as_filelike.return_value = mock.Mock()
+    mem.address = 0x67800000
+
+    # Check that calling calloc_sdram() calls the controller correctly
+    addr = machine_control.calloc_sdram(cn, n_bytes)
+
+    # Assert that the returned address is correct
+    assert addr == mem.address
+
+    # Check that sufficient zeroes were written
+    mem.write.assert_called_once_with(b'\x00' * n_bytes)
+
+
 class TestTestAndBoot(object):
     def test_board_is_checked(self):
         """Test that we're happy if the board responds to an sver."""