What is FP register in ARM?
The fp keeps track of the variables from function to function. It is a frame or picture window on the stack for that function. The ABI defines a layout of this frame. Typically the lr and other registers are saved here behind the scenes by the compiler as well as the previous value of fp .
What does FP mean in assembly?
the fp stands for the frame pointer which is used as a base pointer to local variables on the stack.
What is a FP register?
The floating-point register is used to execute the instruction. There are thirty-two 64-bit floating-point registers, numbered from floating-point register 0-31. All floating-point instructions provide a 5-bit field that specifies which floating-point registers to use in the execution of the instruction.
How many registers does ARM have?
ARM processors, with the exception of ARMv6-M and ARMv7-M based processors, have a total of 37 registers, with 3 additional registers if the Security Extensions are implemented, and in ARMv7-A only, 3 more if the Virtualization Extensions are implemented. The registers are arranged in partially overlapping banks.
What is the function of the SP register?
The Stack Pointer (SP) register is used to indicate the location of the last item put onto the stack. When you PUT something ONTO the stack (PUSH onto the stack), the SP is decremented before the item is placed on the stack.
What is Stmfd?
Store Multiple Decrement Before (Store Multiple Full Descending) stores multiple registers to consecutive memory locations using an address from a base register.
How and when is the link register used?
R14, link register (LR) R14 is also called the Link Register (LR). This is used for holding the return address when calling a function or subroutine. At the end of the function or subroutine, the program control can return to the calling program and resume by loading the value of LR into the Program Counter (PC).
Does R11 exist in arm assembly register set?
Although register R11 is a “general purpose” register, in practice, we have assign it for a specific purpose…. So register R11 may be considered as a special purpose register (i.e.: don’t use register r11 to store value for computation !) The IP register is used as temporary (sratch) register.
What are the differences between register and main memory?
The main difference between register and main memory is that a register is a small and fast storage inside the CPU that holds data temporarily while the main memory is a storage component in the computer that stores data and programs currently used by the CPU. A register is a high-speed memory location in the CPU.
What is R12 register in ARM?
The choice of R12 allows some systems to use R9-R11 as callee-saved general purpose registers without disrupting any sequence of similar registers. From the APCS, The ip register has a dedicated role only during function call; at other times it may be used as a scratch register.
What are ARM banked registers?
A banked register maps one-to-one onto a user mode register. If you change processor mode, a banked register from the new mode will replace an existing register. For example, when the processor is in the interrupt request mode, the instructions you execute still access registers named r13 and r14.
What is the meaning of ORG $1000 when writing the code?
ORG $1000: this tells the assembler that this program will be located and organized in memory at address $1000. START: this is the first instruction of the program, it is also considered a subroutine.
What type of registers are available in ARM processors?
ARM processors provide general-purpose and special-purpose registers. Some additional registers are available in privileged execution modes. In all ARM processors, the following registers are available and accessible in any processor mode: 13 general-purpose registers R0-R12.
What is SP register in ARMv6-M?
In ARMv6-M and ARMv7-M based processors, SP is an alias for the two banked stack pointer registers: Main stack pointer register, which is only available in privileged software execution. Process stack pointer register.
What are the general purpose registers in an ARM microcontroller?
Generally all ARM registers are general purpose. The lr (link register, also R14) and pc (program counter also R15) are special and enshrine in the instruction set.
What is the UN Register of conventional arms?
UN Register of Conventional Arms. Transparency in armaments is a key confidence-building measure. It may encourage restraint in the transfer or production of arms, and can contribute to preventive diplomacy. The UN Register of Conventional Arms (UNROCA) has received reports from more than 170 States.