可以使用MARS来编汇编,MARS是一个用java编的IDE,它是一个模拟环境.
样例:重要的句子输出三遍
.data str: .asciiz "weidiao is great " .text j main f: la $a0,str li $v0,4 syscall jr $ra main: li $t1,0 li $t2,3 loop: bgt $t1,$t2,over addi $t1,$t1,1 jal f j loop over: li $v0,10 syscall
指令文档:链接
下面程序为一个四则运算程序,学习汇编就是要大量的阅读实例.实例学习在编程技术中至关重要.
#simple example :a small calculater’
.text # text section
.globl main # call main by SPIM
main:
la $t0, value
#t0 is the address of the 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) #operation is stored to t0+8---the second byte
la $a0,msg1 #v0 controls the syscall.a0 controls the output_data;
li $v0,4
syscall #print "first num:"
li $v0, 5 #load integer 5 to v0,this is the read operation.
syscall
sw $v0, 0($t0) #store $v0
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"
样例:打印九九乘法表
.data op :.asciiz "*" eq:.asciiz "=" line:.asciiz " " space:.asciiz " " .text j main print: move $a0,$t1 li $v0,1 syscall la $a0,op li $v0,4 syscall move $a0,$t2 li $v0,1 syscall la $a0,eq li $v0,4 syscall mult $t1,$t2 mflo $a0 li $v0,1 syscall la $a0,space li $v0,4 syscall blt $t2,$t1,ret la $a0,line syscall ret: jr $ra main: li $t1,0 for1: addi $t1,$t1,1 bgt $t1,9,for1_out li $t2,0 for2: addi $t2,$t2,1 bgt $t2,$t1,for1 jal print j for2 j for1 for1_out: li $v0,10 syscall