Reading the Link Register These can be found in cmsis_gcc. h for the GCC compiler. Reading the LR is similar to reading the MSP except that the MOV instruction is used instead of the MRS instruction.
What is purpose of linkage register?
Used to pass parameters to the supervisor or to a called program. Some system macros expand to include instructions that load a value into one or both of these registers. Others load the address of a parameter list into register 1.
What is link register and program counter?
2.2.3 R14: The Link Register. When a subroutine is called, the return address is stored in the link register. 2.2.4 R15: The Program Counter. The program counter is the current program address. This register can be written to control the program flow.
How does link register work?
A link register is a special-purpose register which holds the address to return to when a function call completes. This is more efficient than the more traditional scheme of storing return addresses on a call stack, sometimes called a machine stack.
Which register is link register in ARM Cortex m3 architecture?
register R14
What is use of link register?
A link register is a special-purpose register which holds the address to return to when a function call completes. This is more efficient than the more traditional scheme of storing return addresses on a call stack, sometimes called a machine stack.
Which register is link register?
R14
Where does link register point?
Each old lr (link register) is stored in the old fp (frame pointer). The sp and fp are a data aspect of functions. Your point B is the active pc and sp . Point A is actually the fp and lr ; unless you call yet another function and then the compiler might get ready to setup the fp to point to the data in B.Nov 15, 2018
What is the use of Cpsr?
The Linux/ARM embedded platform ARM v6/v7 maintains a status register called the CPSR (current program status register) that holds four status bits, negative (N), zero (Z), carry (C), and overflow (O). These bits can be used for conditional execution of subsequent instructions.
What is the uses of link register?
A link register is a special-purpose register which holds the address to return to when a function call completes. This is more efficient than the more traditional scheme of storing return addresses on a call stack, sometimes called a machine stack.