Initial import of NFC GNSS SDK project

ql-kernel/threadx/common/include/constant_time.h

@@ -0,0 +1,33 @@
+/**
+ *  Constant-time functions
+ *
+ *  Copyright The Mbed TLS Contributors
+ *  SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later
+ */
+
+#ifndef MBEDTLS_CONSTANT_TIME_H
+#define MBEDTLS_CONSTANT_TIME_H
+
+#include <stddef.h>
+
+
+/** Constant-time buffer comparison without branches.
+ *
+ * This is equivalent to the standard memcmp function, but is likely to be
+ * compiled to code using bitwise operation rather than a branch.
+ *
+ * This function can be used to write constant-time code by replacing branches
+ * with bit operations using masks.
+ *
+ * \param a     Pointer to the first buffer.
+ * \param b     Pointer to the second buffer.
+ * \param n     The number of bytes to compare in the buffer.
+ *
+ * \return      Zero if the content of the two buffer is the same,
+ *              otherwise non-zero.
+ */
+int mbedtls_ct_memcmp(const void *a,
+                      const void *b,
+                      size_t n);
+
+#endif /* MBEDTLS_CONSTANT_TIME_H */