Syntax
#define SEGGER_RTT_LOCK() { \
unsigned int _SEGGER_RTT__LockState; \
__asm volatile ("mrs %0, basepri \n\t" \
"mov r1, %1 \n\t" \
"msr basepri, r1 \n\t" \
: "=r" (_SEGGER_RTT__LockState) \
: "i"(SEGGER_RTT_MAX_INTERRUPT_PRIORITY) \
: "r1", "cc" \
);