Understanding ARM Registers

In any ARM processor, total 16 registers are accessible in any operation Mode. Those registers are as shown in following image,

  • 13 general-purpose registers R0-R12
  • Stack Pointer (SP)
  • Link Register (LR)
  • Program Counter (PC)
  • Application Program Status Register (APSR)’

The meaning and purpose of this ARM registers is as below,

  • R0 to R12 – The initial 13 registers are called general purpose registers and those can used to save any data or address.
  • R13 – is used as the stack pointer (sp) and it stores the head of the stack memory in the current processor.
  • R14 – is called as the link register (lr). In R14 register processor puts the return address whenever it calls a function.
  • R15 – is called as program counter (pc) and it contains the address of the next instruction to be fetched / executed by the processor.

Refer information from http://www.cecmohali.org/resource-material/notes/Notes-2.pdf for more understanding.

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