Compare an arrays element. Switch statement/if else - Assembly - MIPS
This is my first project sorry for my lack of knowledge, this is the code I'm trying to replicate.
int A[3] = {0, 1, 2};
int x;
for ( int i = 0; i < 3; i++ )
{
if ( A[i] > 1 )
x = 1;
else
{
switch ( A[i] )
{ case 0:
x = 2;
case 1:
x = 3;
}
}
printf(“%d”, x);
}
This is the code that I have in assembly.
main: li $s0, 0
sw $s0, ($s7) #int A[0] = {0};
li $s0, 1
sw $s0, 4($s7) #int A[1] = {1};
li $s0, 2
sw $s0, 8($s7) #int A[2] = {2};
li $s1, 1 #initialize x = 1
li $s0, 0 #initialize i = 0
li $s2, 3 # constant 3
li $s3, 1 # constant 1
start: blt $s0, $s2, for
j finish
for: add $t1,$s0,$s0 #reg $t1 = 2*i
add $t1,$t1,$t1 #reg $t1 = 4*i
add $t0,$t1,$s7
bgt $t0, $s3, exone #a[i] is greater than 1 how to increment the array up?
#switch statement
lw $t0, 0($t1)
jr $t0
j start
L0: add $s0, $s0, 1
li $s1, 2
j print
L1: add $s0, $s0, 1
li $s1, 3
j print
exone: add $s0, $s0, 1
li $s1, 1
j print
print: li $v0, 1 # print integer
move $a0, $s1 # what to print is stored at $s1
syscall
j start
finish: li $v0, 10 # exit system call
syscall
I'm not sure where I'm going wrong it compiles but doesn't give me the output I want or any output for that matter.
Based on some info I have updated my code.
main: add $s0,$zero, $zero
li $s7, 200
sw $s0, 0($s7) #int A[0] = {0};
addi $s0, $s0, 1
sw $s0, 4($s7) #int A[1] = {1};
addi $s0, $s0, 1
sw $s0, 8($s7) #int A[2] = {2};
li $s1, 0 #initialize x = 0
li $s0, 0 #initialize i = 0
li $s2, 3 # constant 3
li $s3, 1 # constant 1
#check to enter the for loop
for: blt $s0, $s2, enter
j finish
#enter the for loop
enter: add $t1,$s0,$s0 #reg $t1 = 2*i
add $t1,$t1,$t1 #reg $t1 = 4*i
add $t0,$t1,$s7 #reg A[i]
l开发者_运维百科w $t2, 0($t0)
bgt $t2, $s3, exone #a[i] is greater than 1 check
#switch statement
jr $t2
#just in case jump back to for loop
j for
#address for the switch statements
L0: add $s0, $s0, 1
li $s1, 2
j print
L1: add $s0, $s0, 1
li $s1, 3
j print
#address for the if else statement
exone: add $s0, $s0, 1
li $s1, 1
j print
print: li $v0, 1 # print integer
move $a0, $s1 # what to print is stored at $s1
syscall
j for
finish: li $v0, 10 # exit system call
syscall
The output should be “231”.
# [snip]
add $t0,$t1,$s7 #reg A[i]
lw $t2, 0($t0)
bgt $t2, $s3, exone #a[i] is greater than 1 check
#switch statement
jr $t2
This is wrong jr
means Jump Register and it jumps to the address contained in $t2
( which at this point contains a[i]
, which here is 0, 1 or 2 -- not great addresses to jump to).
You could do a lot of things to correct this (I'll assume you meant to have break
statements in your C code), but here's some quick untested code that mimics the switch with a set of if-statements:
li $t3, 0
beq $t2, $t3, L0 # if (a[i] == 0) goto L0
li $t3, 1
beq $t2, $t3, L1 # if (a[i] == 1) goto L1
j print # else fall through
Pumphouse:
First be sure what you want to do,your program does not have any proper aim.
All though you should have to note some points like,
- switch-case should must have "default" otherwise it may create a big problem.
Variables should be declared always on the top of program
not in the loop. variables of same type should be declare together.
.data
array: .word 0 : 3
.text
.globl main
main: la $s7, array
add $s0, $zero, $zero
sw $s0, 0($s7) #int A[0] = {0};
addi $s0, $s0, 1
sw $s0, 4($s7) #int A[1] = {1};
addi $s0, $s0, 1
sw $s0, 8($s7) #int A[2] = {2};
add $s1, $zero, $zero #initialize x = 0
add $s0, $zero, $zero #initialize i = 0
li $s2, 3 # constant 3
li $s3, 1 # constant 1
#check to enter the for loop
for: blt $s0, $s2, enter
j finish
#enter the for loop
enter: add $t1,$s0,$s0 #reg $t1 = 2*i
add $t1,$t1,$t1 #reg $t1 = 4*i
add $t0,$t1,$s7 #reg A[i]
lw $t2, 0($t0)
bgt $t2, $s3, exone #a[i] is greater than 1 check
#switch statement I would like to know how to properly do this with a jr
beq $t2, $zero, L0
beq $t2, $s3, L1
#just in case jump back to for loop
j for
#address for the switch statements
L0: add $s0, $s0, 1
li $s1, 2
j print
L1: add $s0, $s0, 1
li $s1, 3
j print
#address for the if else statement
exone: add $s0, $s0, 1
li $s1, 1
j print
print: li $v0, 1 # print integer
move $a0, $s1 # what to print is stored at $s1
syscall
j for
finish: li $v0, 10 # exit system call
syscall
So this works it wasn't exactly how I wanted to do it but it works I wanted to use a jr in the switch statement but I'm not quite there yet.
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