• cpu_irq_critical_section_counter : interrupt_sam_nvic.h
• cpu_irq_prev_interrupt_state : interrupt_sam_nvic.h
• ptr_get : read.c , stdio_serial.h
• ptr_put : write.c , stdio_serial.h
• setup_block : example.c
• status : example.c
• stdio_base : write.c , read.c , stdio_serial.h