An analysis of arm learning B,BL instruction

B or BL instruction causes the processor to transfer to the "subroutine name" to begin execution. The difference between the two is that the BL instruction copies the address of the next instruction to the R14 (LR, link register) before it is transferred to the sub-program execution.

Since the BL instruction saves the address of the next instruction, it is possible to return the subroutine using the instruction "MOV PC, LR". and the B instruction can not realize the return of the subroutine, can only realize the simple jump. When programming, the user can choose the appropriate subroutine call statement according to the specific application.