What is the instruction LDR R0 R1 does?
Generally, LDR is used to load something from memory into a register, and STR is used to store something from a register to a memory address. LDR R2, [R0] @ [R0] – origin address is the value found in R0. STR R2, [R1] @ [R1] – destination address is the value found in R1.
What is the value of R0 at the end of the assembly code?
Application termination R0 equal to angel_SWIreason_ReportException ( 0x18 ).
What will be the contents of register R0?
In the first type, the contents of register R0 or Rl of current register bank provide an 8-bit address that is multiplexed with data on port 0. Eight bits are sufficient for external I/O expansion decoding or for a relatively small RAM array. In the second type, the Data Pointer is used for generating 16-bit address.
What is the difference between LDR and LDRB?
LDRSB (Load Register Signed Byte) loads a byte from memory, sign-extends it to form a 32-bit word, and writes the result to a general-purpose register. LDRB (Load Register Byte) loads a byte from memory, zero-extends it to form a 32-bit word, and writes the result to a general-purpose register.
What does add R1 R2 R3 mean?
ADD: This instruction adds 2 values (from 2 registers or from a register and an immediate value) and puts them into a register. Similar format is used for SUB, MULT, DIV, MOD. For eg. “ADD R1 R2 R3;” will move the value R2+R3 into R1. “ADD R1 R2 #3;” will move the value R2 + 3 into R1.
What is DCB in arm?
The DCB directive allocates one or more bytes of memory, and defines the initial runtime contents of the memory.
What is meant by LDR?
Informal. long-distance relationship: a relationship, typically a romantic one, in which the two people live far enough apart that they cannot see each other often: My boyfriend and I had an LDR for two years.
How many bits are STR and LDR?
Load register and store register, 32-bit word or 8-bit unsigned byte. Byte loads are zero-extended to 32 bits.
What 3 registers make up the CPSR register?
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.
How does LDR work in ARM?
LDR instructions load a register with a value from memory. STR instructions store a register value into memory. The memory address to load from or store to is at an offset from the register Rn . The offset is specified by the register Rm and can be shifted left by up to 3 bits using LSL .