MIPS assembly language common instruction introduction

“This is the 22nd day of my participation in the November Gwen Challenge. See details of the event: The Last Gwen Challenge 2021”.

Introduction to the

We know that x86 architecture CPU is used in PC and workstation more,ARM architecture CPU is commonly found in mobile phones and microcontrollers, then MIPS architecture CPU mainly in which devices can be found their figure?

• In China the godson
• playstation

Learning environment building

• Install JDK, mainly used to run MIPS emulator Mars
• MARS simulator: courses.missouristate.edu/KenVollmar/…

register

In MIPS, there are 32 universal registers starting with $

| | | register number register name register purpose | | : — — — — — — — — — — : | : — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — : | : — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — : | | | 0 ∣ 0 0 ∣ zero | always returns 0 | | 1 ∣ | 1 ∣ | at | keep register | 2-2-2-3 | where v0 – where v0 – where v0 – v1 | generally used to store the expression or function return value (the value of the abbreviated) | | 4-4-4-7 | a0 – a0 – a0 – a3 (Argument () | | parameter register | 8-8-8-15 | t0 – t0 – t0 – t7 has | Commonly used to store temporary variables (temp abbreviated) | | 16-16-16-23 | s0 – s0 – s0 deposit – s7 | sub function call process data need to be retained (saved values) | | 24-24-24-25 | t8 – t8 – t8 – t9 with | attributes T0 – t0 – t0 – t7 has | | – 26 of 26-26-27 | k0 – k0 – k0 – k1 general storage interrupt function return value | | | 28 ∣ 28 28 ∣ gp | | GlobalPointer shorthand | | 29 ∣ 29 | 29 ∣ sp | stack pointer, Pointing to the top (Stack Pointer shorthand) | | 30 ∣ 30 | 30 ∣ s8 / fp ∣ (Save/FramePointer) Frame Pointer ∣ ∣ fp | (Save/Frame Pointer) Frame Pointer | | Fp ∣ (Save/FramePointer) frame pointer ∣ ∣ | $31 ra | general used to store the function return address (return address abbreviated) |

Register numbers and aliases correspond one by one. The same register can be represented in two different ways: 0∗∗ or ∗∗0** or **0∗∗ or ∗∗ Zero

• Program Counter (PC) cannot be modified directly, but can be changed by jump instruction
• HI and LO: These two registers are specifically used to hold the results of multiplication, division, and multiplication accumulation.

Segmentation processing in MIPS assembly

.data # text # code segmentCopy the code

Transfer instructions

1. Load the immediate count instructionli

Li (load immediate) : transfers immediate data to a register

Li $t0, 1; Hexadecimal data is represented with a 0x prefixCopy the code

2. Load address instructionla

Load Address (LA) : used to transfer an address to a register and obtain an address in a data segment from an address

.data MSG:.ascii "hello world". Text la $a0, MSG # assign the address of the string data to register $a0Copy the code

3. Register data transfer instructionmove

Used to transfer data from one register to another

Move $t0,$t1 # move $t1 to $t0Copy the code

System service instructionsyscall

You can use printf to output text in C, but there is no such thing as printf in assembly. If you want to output text, you need to use the syscall instruction

If you want to output a digit 1, the **syscall instruction extracts the desired output from the $A0 register **

Therefore, you need to place the data in $a0 before executing syscall:

The syscall li $a0, 1Copy the code

You also need to specify the output data type, which is stored in the $v0 register

# $v0=1, syscall--->print_int
# $v0=4, syscall--->print_string
Copy the code

$v0 stores 1, indicating that Syscall will output the data in $a0 as a number

$v0 is stored to 4, indicating that Syscall treats the data in $A0 as the address of the data and prints the corresponding data

The syscall command reads and writes the table

Print the helloWorld example using the syscall command:

ASCII "hello world\0" # char* MSG ="hello world". Text la $a0, MSG li $v0,4 syscallCopy the code

Mips assembler instruction summary table

Mips memory structure diagram: