I seem to be having a issue understanding part of the project my teacher assigned.
So the basic Idea is that I have a .word "table", Full of IP addresses. I need to be able to traverse the table and compare the different values and match the numbers up with user input. I also need to account for any size table, not just the table that he gave us.
I first tested out trying to get through the table first, because I have never worked with the .word before. I figured out how to load the table, and how to use the offsets for one line, the issue is when I try to get to the next line. I thought that I was supposed to use:
addi $a0, 20
I have also tried the addu and add instructions.
This was to get to the next line, however I get to an Exception 4, which is a data fetch error. This happens after I try to load a new word like:
lw $s0, ($a0)
I am not really sure what to do from here, I know that $a0 is getting incremented outside of where the table is, I am just unsure how to fix it or what the actual code should be. Here is what I am using to test with.
.data
MESSAGE1: .asciiz "Enter an IP address\n"
MESSAGE2: .asciiz "First: "
MESSAGE3: .asciiz "Second: "
MESSAGE4: .asciiz "Third: "
MESSAGE5: .asciiz "Fourth: "
MESSAGE6: .asciiz "The IP address you enterd: "
MESSAGE7: .asciiz "."
MESSAGE8: .asciiz "\nClass A address\n"
MESSAGE9: .asciiz "\nClass B address\n"
MESSAGE10: .asciiz "\nClass C address\n"
MESSAGE11: .asciiz "\nClass D address\n"
MESSAGE12: .asciiz "\nInvalid domain class\n"
MESSAGE13: .asciiz "\nProgram successfully completed . . .\n"
MESSAGE14: .asciiz "\n"
MESSAGE15: .asciiz "Matching domain found at: "
MESSAGE16: .asciiz "Matching domain was NOT found . . . \n"
ERROROVER: .asciiz "The entered number is larger than 255.\n"
ERRORUNDER: .asciiz "The entered number is smaller than 0.\n"
ERROR: .asciiz "Invalid Number detected make sure the number entered is
between 0 and 255."
IP_ROUTING_TABLE_SIZE:
.word 10
IP_ROUTING_TABLE:
# line #, x.x.x.x -------------------------------------
.word 0, 146, 92, 255, 255 # 146.92.255.255
.word 1, 147, 163, 255, 255 # 147.163.255.255
.word 2, 201, 88, 88, 90 # 201.88.88.90
.word 3, 182, 151, 44, 56 # 182.151.44.56
.word 4, 24, 125, 100, 100 # 24.125.100.100
.word 5, 146, 163, 140, 80 # 146.163.170.80
.word 6, 146, 163, 147, 80 # 146.163.147.80
.word 10, 201, 88, 102, 80 # 201.88.102.1
.word 11, 148, 163, 170, 80 # 146.163.170.80
.word 12, 193, 77, 77, 10 # 193.77.77.10
.text
.globl main
main:
la $a0, IP_ROUTING_TABLE
lw $s0, ($a0)
lw $s1 4($a0)
lw $s2, 8($a0)
lw $s3, 12($a0)
lw $s4, 16($a0)
li $v0, 1
move $a0, $s0
syscall
li $v0, 4
la $a0, MESSAGE14
syscall
li $v0, 1
move $a0, $s1
syscall
li $v0, 4
la $a0, MESSAGE14
syscall
li $v0, 1
move $a0, $s2
syscall
li $v0, 4
la $a0, MESSAGE14
syscall
li $v0, 1
move $a0, $s3
syscall
li $v0, 4
la $a0, MESSAGE14
syscall
li $v0, 1
move $a0, $s4
syscall
li $v0, 4
la $a0, MESSAGE14
syscall
addi $a0, 20
lw $s0, ($a0) #problem is here
li $v0, 1
move $a0, $s0
syscall
P_EXIT: jr $31
Sorry this became more lengthy than it probably should have been, I just wanted to make sure it was understood what was happening. Thanks for the help.
Also, I have tried using the debugger and it hasn't helped me figure out the issue.
