(1) ARM instruction format

The basic format of the arm instruction is as follows:

<opcode>{<cond>}{s}{. W\. N} <rd>,<rn>{,<operand2>}

opcode: Instruction mnemonics, such as Mov,add, etc.

Cond: Execution conditions

S: Specifies whether the directive affects the value of the CPSR register, such as Adds,subs, etc.

. W\. N: instruction width specifier,. W is 32 bits,. N is 16 bits, the default is 16 bits

Rd: Destination Register

Rn: For the first operand register

Operand2: The second operand, which can be an immediate number, register or register displacement operation, such as SUB R2,R3,R4 LSL #2

(1) ARM instruction format