CMSIS notes

• https://arm-software.github.io/CMSIS_5/Core/html/index.html

• https://arm-software.github.io/CMSIS_5/Core/html/using_TrustZone_pg.html

In CMSIS file `arm_math.h`:

 503   /**
 504    * @brief Error status returned by some functions in the library.
 505    */
 506 
 507   typedef enum
 508   {
 509     ARM_MATH_SUCCESS        =  0,        /**< No error */
 510     ARM_MATH_ARGUMENT_ERROR = -1,        /**< One or more arguments are incorrect */
 511     ARM_MATH_LENGTH_ERROR   = -2,        /**< Length of data buffer is incorrect */
 512     ARM_MATH_SIZE_MISMATCH  = -3,        /**< Size of matrices is not compatible with the operation */
 513     ARM_MATH_NANINF         = -4,        /**< Not-a-number (NaN) or infinity is generated */
 514     ARM_MATH_SINGULAR       = -5,        /**< Input matrix is singular and cannot be inverted */
 515     ARM_MATH_TEST_FAILURE   = -6         /**< Test Failed */
 516   } arm_status;