Arm assembly syntax

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Catalog

ARM Basic assembly syntax

1.1 Processor internal data transfer instructions

1.2 Memory access instructions

1.3 Stack pressing and out of stack instructions

1.4 Jump instruction

1.5 Arithmetic instructions

1.6 Logical operation instructions

2 Other instructions

2.1—str

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ARM Basic assembly syntax

1.1 Processor internal data transfer instructions

mov： Copy data from one register to another , Or pass an immediate value into a register

MOV R0, R1     @ Register R1 The number in is passed to R0 R0=R1
MOV R0, #0x12  @ Will count immediately 0x12 Pass to R0 R0=0x12

 MRS： Read special registers （CPSR and SPSR） The data in is passed to the general register

MRS R0, CPSR  @ hold CPSR The data is passed to R0,R0=CPSR

MSR： Pass the data from the ordinary register to the special register

MSR CPSR, R0  @ hold R0 The data is passed to CPSR,CPSR=R0

1.2 Memory access instructions

 LDR： Load an immediate into a register , Or read the value of a register to another register

SR： Write data to a register

LDR R0, 0X0209C004 @ take  0X0209C004 The value of the address   to R0 
LDR R1, R2 @ take  R2 The value in   to  R1 
LDR R1, =0X123456789  @ take 0X123456789 This address is written to R1 in , That is to say, now R1=0x123456789


STR R0,[R1],＃8      @ take R0 The word data in is written to R1 In memory for address , And put the new address R1＋8 write in R1.
STR R0,[R1,＃8]       @ take R0 The word data in is written to R1＋8 In memory for address .”
str     r1, [r0]        @ take r1 Register value , The value transmitted to the address is r0 Of （ Memory ） In the memory 

matters needing attention ： In the above code , for the first time LDR It's a 0X0209C004 The value of this position gives R0, third time LDR Is to write the address R1

【Rx】： Represents the address of this register

1.3 Stack pressing and out of stack instructions

Used to call each other between functions .

Pressing stack ：PUSH,STMFD SP！

Out of the stack ：POP,LDMFD SP！

PUSH{R0~R2,R12}
POP{R0~R2,R12}

STMFD SP！{R0~R2,R12}
LDMFD SP！{R0~R2,R12}

1.4 Jump instruction

B： Used to jump out of a function and never come back

_start
    ldr sp, =0x80200000
    b main

 BL： It is used to continue the process of the current function after the function is called

push {r0, r1} @ preservation  r0,r1
cps #0x13 @ Get into  SVC  Pattern , Allow other interrupts to go in again 
bl system_irqhandler @ load  C  Language interrupt handler to  r2  In the register 
cps #0x12 @ Get into  IRQ  Pattern 
pop {r0, r1} 
str r0, [r1, #0X10] @ Interrupt execution complete , Write  EOIR

1.5 Arithmetic instructions

1.6 Logical operation instructions

2 Other instructions

2.1 Coprocessor functions

MCR{cond} p15,<opc1>,<Rt>,<CRn>,<CRm>,<opc2> take ARM The data of the register is written to CP15 Coprocessor register .

MRC p15,0,r0,c0,c0,0   take CP15 The register data in the coprocessor reads ARM In the register .

 2.2 Bit clearing and bit or function

 bic     r1,  r0, #(0x1 << 11)    hold (0x1 << 11) Reverse later , And then on r0, Write this value again r1

orr r0, r0, #0x12      r0 Or on the 0x13, Said the use of IRQ Pattern

2.3 Isolation

DSB
Data synchronization isolation . Only after all the memory access operations in front of it are completed , To execute the instructions that follow it （ That is, any instruction must wait for memory access Ask operation ）
ISB
Command synchronization isolation . The strictest ： It cleans the assembly line , To ensure that after all the instructions in front of it have been executed , To execute the instructions that follow it .