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-rw-r--r--lib/test_fpu_impl.c37
1 files changed, 37 insertions, 0 deletions
diff --git a/lib/test_fpu_impl.c b/lib/test_fpu_impl.c
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+++ b/lib/test_fpu_impl.c
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+// SPDX-License-Identifier: GPL-2.0+
+
+#include <linux/errno.h>
+
+#include "test_fpu.h"
+
+int test_fpu(void)
+{
+ /*
+ * This sequence of operations tests that rounding mode is
+ * to nearest and that denormal numbers are supported.
+ * Volatile variables are used to avoid compiler optimizing
+ * the calculations away.
+ */
+ volatile double a, b, c, d, e, f, g;
+
+ a = 4.0;
+ b = 1e-15;
+ c = 1e-310;
+
+ /* Sets precision flag */
+ d = a + b;
+
+ /* Result depends on rounding mode */
+ e = a + b / 2;
+
+ /* Denormal and very large values */
+ f = b / c;
+
+ /* Depends on denormal support */
+ g = a + c * f;
+
+ if (d > a && e > a && g > a)
+ return 0;
+ else
+ return -EINVAL;
+}