Implicit declaration is invalid warning for __set_BASEPRI() function in Keil
__get_BASEPRI() is defined in cmsis_armcc.h, but only if __TARGET_ARCH_7E_M (ARMv7-M, Cortex-M3) or __TARGET_ARCH_7E_M (ARMv7E-M, Cortex-M4, M7) is defined.  The BASEPRI special register is not supported in ARMv6-M, Cortex-M0, M0+, and M1.  Make sure you have the correct device selected in the Options for Target dialog.