mips彙編簡單實例——一個小計算器

其實開始的時候一直在看 mips的指令格式，看了、忘了，沒什麼效果。

 

現在通過這個例子，簡單訓練一下： mips彙編中：

 

常用寄存器的使用；

系統調用： 1(print_int),4(print_str),5(read_int),10(exit)；

算術運算： add,sub,mul,div；

邏輯運算及跳轉；

 

上代碼：(彙編寫的少，代碼書寫、風格還很差勁，感謝請大蝦指教)：

 

#sample example 'a small calculater’ .text # text section .globl main # call main by SPIM main: la $t0, value # load address "value" into $t0 la $a0,msg0 li $v0,4 syscall #print "please choose the operation:" li $v0, 5 syscall sw $v0, 8($t0) la $a0,msg1 li $v0,4 syscall #print "first num:" li $v0, 5 syscall sw $v0, 0($t0) la $a0,msg2 li $v0,4 syscall #print " second num:" li $v0, 5 syscall sw $v0, 4($t0) #read the other num la $a0,newline li $v0,4 syscall #print "/n" lw $t1, 0($t0) # load the first num lw $t2, 4($t0) # load the second num lw $t3, 8($t0) # load the operation beq $t3,1,addOp # if + beq $t3,2,subOp # if - beq $t3,3,mulOp # if * beq $t3,4,divOp # if / addOp: add $t4, $t1, $t2 # $t1 + $t2 = $t4 sw $t4, 12($t0) # la $t5,addFlag j printResult subOp: sub $t4, $t1, $t2 # $t1 - $t2 = $t4 sw $t4, 12($t0) la $t5,subFlag j printResult mulOp: mul $t4, $t1, $t2 # $t1 * $t2 = $t4 sw $t4, 12($t0) la $t5,mulFlag j printResult divOp: div $t4, $t1, $t2 # $t1 / $t2 = $t4 sw $t4, 12($t0) la $t5,divFlag j printResult printResult: lw $a0,0($t0) li $v0,1 syscall #read first number la $a0,0($t5) li $v0,4 syscall #print opflag lw $a0,4($t0) li $v0,1 syscall #print second number la $a0,equalStr li $v0,4 syscall #print " = " lw $a0,12($t0) li $v0,1 syscall # print sum result j exit exit: la $a0,newline li $v0,4 syscall #print " /n " li $v0,10 syscall # exit # data section .data value: .word 0, 0, 0 ,0 ,0 # 0: first num ,4 : second num , 8 : operation , 12:result msg0 : .asciiz " please choose the operation(1~4):/n/t/t1 : +,addition /n/t/t2 : -,subtracter/n/t/t3 : * multiplication /n/t/t4 : /,division/n" msg1 : .asciiz "first num:" msg2 : .asciiz "second num:" addFlag : .asciiz " + " subFlag : .asciiz " - " mulFlag : .asciiz " * " divFlag : .asciiz " / " equalStr : .asciiz " = " newline : .asciiz "/n===============================/n" 

 

運行效果截圖如下：

 

 

 

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