MIPS - 訪問指令地址以獲得操作碼

Question

我正在編寫一個程序，在該程序中循環訪問代碼並計算I，J和R類型指令的數量。我將如何去訪問指令的操作碼？

Answer 1

.data 
typeR: .word 0x00 #for all TypeR opc code 
typeJ: .word 0x01 #we will have to left shit one bit when comparing 
typeI: .word 0x11 #this is a dummy value because if it's not R or J, it is I 

numR: .word 0 
numJ: .word 0 
numI: .word 0 

endProgram: .word 0x11111111 # you would have to know the address of the #last instruction. Assume for now 

.text 
main: 
lw $s0, countR 
lw $s1, countJ 
lw $s2, countI 

#here you load the address of the first instruction of the program you try 
#to loop though say 0x00000000 
la $t0, 0x00000000 
#here load the instruction code in 0x11111111 to register $t1 
lw $t1, endProgram 

Loop: 

lw $s3, 0($t0) # load first instruction code to $s3 

beq $s3, typeR, R #if equal goes to R 
sll $s3, $s3, 1 # so we get rid of the first digit 
beq $s3, typeJ, J # if equal got to J 
J I # this is the else 

R: 
addi $s0,$s0, 1 #increment countR 
j next 
J: 
addi $s1, $s1, 1#increment countJ 
j next 
I: 
addi $s2, $s2, 1 # increment countI 
j next 

next:#check if it is the end yet, if not keep going to next instruction 
lw $s5, 0($t1) 
beq $s5, $t1, exit # if it is last instructin go to exit 

#if not keep going 
addi $t1, $t1, 4 #move to next instruction since each is 4 byte 
j loop 
exit: 
# I think the last part is pretty simple, depend on what you want to do just #print it out or something, so I've save some typing.