backend_tests.py 文件源码

def test_bitfield(self):
        ffi = FFI(backend=self.Backend())
        ffi.cdef("struct foo { int a:10, b:20, c:3; };")
        assert ffi.sizeof("struct foo") == 8
        s = ffi.new("struct foo *")
        s.a = 511
        py.test.raises(OverflowError, "s.a = 512")
        py.test.raises(OverflowError, "s[0].a = 512")
        assert s.a == 511
        s.a = -512
        py.test.raises(OverflowError, "s.a = -513")
        py.test.raises(OverflowError, "s[0].a = -513")
        assert s.a == -512
        s.c = 3
        assert s.c == 3
        py.test.raises(OverflowError, "s.c = 4")
        py.test.raises(OverflowError, "s[0].c = 4")
        s.c = -4
        assert s.c == -4