When i run my code i got this
-- program is finished running (dropped off bottom) --
This is my code
.data
array: .space 12 # Reserve 12 bytes of memory for the array
.text
la $t0, array # Load the address of the array into $t0
li $v0, 4 # System call code for printing a string
la $a0, prompt # Load the address of the prompt string
syscall # Print the prompt
.data
prompt: .asciiz "Enter three integers: "
li $v0, 5 # System call code for reading an integer
syscall # Read the first integer
sw $v0, 0($t0) # Store the first integer in the first word of the array
li $v0, 5 # Read the second integer
syscall
sw $v0, 4($t0) # Store the second integer in the second word of the array
li $v0, 5 # Read the third integer
syscall
sw $v0, 8($t0) # Store the third integer in the third word of the array
lw $t1, 0($t0) # Load the first integer into $t1
lw $t2, 4($t0) # Load the second integer into $t2
lw $t3, 8($t0) # Load the third integer into $t3
add $t4, $t1, $t2 # Add the first two integers and store the result in $t4
add $t4, $t4, $t3 # Add the third integer and store the result in $t4
sw $t4, sum # Store the sum in memory
.data
sum: .word 0
li $t5, 3 # Load the value 3 into $t5
div $t4, $t5 # Divide the sum by 3 to get the average
mflo $t4 # Store the result of the division in $t4
sw $t4, avg # Store the average in memory
.data
avg: .word 0
li $t0, 3 # Load the value 3 into $t0
li $t1, 0 # Load the value 0 into $t1
loop:
lw $t2, 0($t0) # Load the next integer from the array into $t2
add $t1, $t1, $t2 # Add the current integer to the sum
addi $t0, $t0, 4 # Move to the next word in the array
bne $
goodday, so currently my code prompts the user to enter a sum. my program then takes these stored values and outputs the sum of them. However, currently my code is not outputting the correct total and i am unsure where the problem lies.
i have attached my code below:
.text
main:
#Prompt
la $a0, prompt
li $v0, 4
syscall
# Get input string
li $v0, 8
la $a0, string_input
li $a1, 1024
move $t0, $a0
syscall
# initialise sum
lb $t2, ($t0) # Initialise the sum as the first value
addi $t2, $t2, -48 # Convert to decimal value
addu $t0, $t0, 1
b loop
loop:
lb $t3, ($t0) # Store the sign
lb $t1, 1($t0) # Store the value
addu $t0, $t0, 2 # increment the counter
beq $t1, 10, end_loop # If reached the end of the string
# Manipulate sign value to 1 if '+'
add $t3, $t3, 4
add $t2, $t2, $t1 # Add the value to the sum
b loop # re-iterate
end_loop:
# Printing the total sum
move $a0, $t2
li $v0, 1
syscall
# Exiting program
li $v0, 10
syscall
.data
string_input: .space 1024
prompt: .asciiz "Enter a sum:\n"
the current output should be 11 but this is what is outputted instead:
Enter a sum:
2+3+6
727
So I am fairly new to mips and am trying to do a hmwk.
The exercise is to create a block of words with 0 as the last word , to count them knowing we don't consider the last element 0 and print out the result.
Here is my code for the moment
.data
blockOfWords: .word 12,43,549,7,60,0
.text
la $a0, blockOfWords #putting address of blockOfWords in $a0
loopStart: sll $t1, $s3,2 #iterates thru blockOfWords by jumping by 4 bytes, $t1=4*i
add $t1,$t1,$a0 #we increment the address by four so as to advance in the array after every iteration
lw $a1, 0($t1) #$a1=blockOfWOrds[i]
beq $a1,$zero, Exit #if the value in $a1[i]==0, exit the loop
addi $s0,$s0,1 #else, increment by one the cnt=$s0
j loopStart #and continue looping thru blockOfWords
Exit:
#how do i print the result?
So instead of doing a shift left logical it is a lot easier to up the memory address in the array
In this way the lw $a1, 0($a0) is just grabbing the beginning of the word
it is then incremented by 4 after a check for the 0. This makes the function much simpler and easier to read.
.data
blockOfWords: .word 12,43,549,7,60,0
.text
main:
la $a0, blockOfWords # Load beginning address into $a0
loopStart:
lw $a1, 0($a0) # load the value at the beginning of $a0 into $a1
beq $a1,$zero, exit # Check if $a1 is 0, if so jump to exit
addi $s0,$s0,1 # Add one to the count
addi $a0, $a0, 4 # Up the intial index of the array by 4, up one word
j loopStart # Re-loop
exit:
li $v0, 1 # Load the value of 1 into the $v0 register
la $a0, ($s0) # Load the counter into the $a0 address
syscall
li $v0, 10 # A value 10 syscall to indicate end of program
syscall
The following program 1. Prints out the array 2. Given a lower and upper bound input by user, determines the min and min index within that range
It runs the print array function.
However, I tried tracing the registers in QTSPIM, it does not correctly assign the lower bound and upper bound to $a0 and $a1 respectively. In fact, $v0 does not seem to even scan anything. To move the scanned input from $v0 to $t0, tried using "move $t0, $v0" instead. The problem still occurs.
# Ask the user for two indices
li $v0, 5 # System call code for read_int
syscall
add $t0, $v0, $zero # store input in $t0
sll $t0, $t0, 2 # relative address position (lower bound)
add $a0, $t9, $t0 # array pointer (lower bound)
li $v0, 5 # System call code for read_int
syscall
add $t0, $v0, $zero # store input in $t0
sll $t0, $t0, 2 # relative address position (upper bound)
add $a1, $t9, $t0 # array pointer (upper bound)
The full code is below. Can anyone enlighten me if there's anything wrong?
# arrayFunction.asm
.data
array: .word 8, 2, 1, 6, 9, 7, 3, 5, 0, 4
newl: .asciiz "\n"
.text
main:
# Print the original content of array
# setup the parameter(s)
la $a0, array # base address of array
add $t9, $a0, $zero # store base address
la $a1, 10 # number of elements in array
# call the printArray function
jal printArray # call function
# Ask the user for two indices
li $v0, 5 # System call code for read_int
syscall
add $t0, $v0, $zero # store input in $t0
sll $t0, $t0, 2 # relative address position (lower bound)
add $a0, $t9, $t0 # array pointer (lower bound)
li $v0, 5 # System call code for read_int
syscall
add $t0, $v0, $zero # store input in $t0
sll $t0, $t0, 2 # relative address position (upper bound)
add $a1, $t9, $t0 # array pointer (upper bound)
# Call the findMin function
# setup the parameter(s)
# call the function
jal findMin # call function
# Print the min item
# place the min item in $t3 for printing
addi $t3, $t1, 0
# Print an integer followed by a newline
li $v0, 1 # system call code for print_int
addi $a0, $t3, 0 # print $t3
syscall # make system call
li $v0, 4 # system call code for print_string
la $a0, newl
syscall # print newline
#Calculate and print the index of min item
la $a0, array
add $t3, $v0, $a0
srl $t3, $t3, 2
# Place the min index in $t3 for printing
# Print the min index
# Print an integer followed by a newline
li $v0, 1 # system call code for print_int
addi $a0, $t3, 0 # print $t3
syscall # make system call
li $v0, 4 # system call code for print_string
la $a0, newl #
syscall # print newline
# End of main, make a syscall to "exit"
li $v0, 10 # system call code for exit
syscall # terminate program
#######################################################################
### Function printArray ###
#Input: Array Address in $a0, Number of elements in $a1
#Output: None
#Purpose: Print array elements
#Registers used: $t0, $t1, $t2, $t3
#Assumption: Array element is word size (4-byte)
printArray:
addi $t1, $a0, 0 #$t1 is the pointer to the item
sll $t2, $a1, 2 #$t2 is the offset beyond the last item
add $t2, $a0, $t2 #$t2 is pointing beyond the last item
l1:
beq $t1, $t2, e1
lw $t3, 0($t1) #$t3 is the current item
li $v0, 1 # system call code for print_int
addi $a0, $t3, 0 # integer to print
syscall # print it
addi $t1, $t1, 4
j l1 # Another iteration
e1:
li $v0, 4 # system call code for print_string
la $a0, newl #
syscall # print newline
jr $ra # return from this function
#######################################################################
### Student Function findMin ###
#Input: Lower Array Pointer in $a0, Higher Array Pointer in $a1
#Output: $v0 contains the address of min item
#Purpose: Find and return the minimum item
# between $a0 and $a1 (inclusive)
#Registers used: $t0 (counter), $t1 (max add), $t2 (min), $v0 (min pos), $t3 (current item)
#Assumption: Array element is word size (4-byte), $a0 <= $a1
findMin:
lw, $t2, 0($a0) # initialise min (value) to the lower bound
addi $t0, $a0, 0 # initialise $t0 (current pointer) to lower bound
addi $t1, $a1, 0 # initialise $t1 (add of end of array) to upper bound
Loop: slt $t4, $t1, $t0
bne $t4, $zero, End # branch to end if upper < lower
lw, $t3, 0($a0) # store the content of the lower array pointer
slt $t4, $t3, $t2 # if current ($t3) < min ($t2), store 1 in $t4
beq $t4, $zero, LoopEnd # if it is 0, go to LoopEnd
addi $t2, $t3, 0 # store content ($t3) as minimum ($t2)
addi $v0, $t0, 0 # store the address of min
LoopEnd: addi, $t0, 4 # increments current pointer lower bound
j Loop # Jump to loop
End:
jr $ra # return from this function
You read in the integers properly. The problems are elsewhere
In findMin function you use lw, $t3, 0($a0), but you should use it with $t0 instead of $a0.
After you return from this function you accidentally save $t1 as min value rather then $t2 which actually holds it.
Also you do not save $v0 which holds the pointer for the min value, so you use some garbage data later on, not the intended one.
When you calculate the index of the min from the pointer you use add, but it should be sub.
Also as it was mentioned in the comments at LoopEnd the add is syntactically wrong. It should be addi $t0, $t0, 4. But this maybe just some copy paste error.
Here is the fixed code. Changed lined marked with ERROR.
# arrayFunction.asm
.data
array: .word 8, 2, 1, 6, 9, 7, 3, 5, 0, 4
newl: .asciiz "\n"
.text
main:
# Print the original content of array
# setup the parameter(s)
la $a0, array # base address of array
add $t9, $a0, $zero # store base address
la $a1, 10 # number of elements in array
# call the printArray function
jal printArray # call function
# Ask the user for two indices
li $v0, 5 # System call code for read_int
syscall
add $t0, $v0, $zero # store input in $t0
sll $t0, $t0, 2 # relative address position (lower bound)
add $a0, $t9, $t0 # array pointer (lower bound)
li $v0, 5 # System call code for read_int
syscall
add $t0, $v0, $zero # store input in $t0
sll $t0, $t0, 2 # relative address position (upper bound)
add $a1, $t9, $t0 # array pointer (upper bound)
# Call the findMin function
# setup the parameter(s)
# call the function
jal findMin # call function
# Print the min item
# place the min item in $t3 for printing
addi $t3, $t2, 0 # ERROR: min is in $t2 not $t1
addi $t4, $v0, 0 # ERROR: not saving the pointer to the min element
# Print an integer followed by a newline
li $v0, 1 # system call code for print_int
addi $a0, $t3, 0 # print $t3
syscall # make system call
li $v0, 4 # system call code for print_string
la $a0, newl
syscall # print newline
#Calculate and print the index of min item
la $a0, array
sub $t3, $t4, $a0 # ERROR: sub should used not add
srl $t3, $t3, 2
# Place the min index in $t3 for printing
# Print the min index
# Print an integer followed by a newline
li $v0, 1 # system call code for print_int
addi $a0, $t3, 0 # print $t3
syscall # make system call
li $v0, 4 # system call code for print_string
la $a0, newl #
syscall # print newline
# End of main, make a syscall to "exit"
li $v0, 10 # system call code for exit
syscall # terminate program
#######################################################################
### Function printArray ###
#Input: Array Address in $a0, Number of elements in $a1
#Output: None
#Purpose: Print array elements
#Registers used: $t0, $t1, $t2, $t3
#Assumption: Array element is word size (4-byte)
printArray:
addi $t1, $a0, 0 #$t1 is the pointer to the item
sll $t2, $a1, 2 #$t2 is the offset beyond the last item
add $t2, $a0, $t2 #$t2 is pointing beyond the last item
l1:
beq $t1, $t2, e1
lw $t3, 0($t1) #$t3 is the current item
li $v0, 1 # system call code for print_int
addi $a0, $t3, 0 # integer to print
syscall # print it
addi $t1, $t1, 4
j l1 # Another iteration
e1:
li $v0, 4 # system call code for print_string
la $a0, newl #
syscall # print newline
jr $ra # return from this function
#######################################################################
### Student Function findMin ###
#Input: Lower Array Pointer in $a0, Higher Array Pointer in $a1
#Output: $v0 contains the address of min item
#Purpose: Find and return the minimum item
# between $a0 and $a1 (inclusive)
#Registers used: $t0 (counter), $t1 (max add), $t2 (min), $v0 (min pos), $t3 (current item)
#Assumption: Array element is word size (4-byte), $a0 <= $a1
findMin:
lw, $t2, 0($a0) # initialise min (value) to the lower bound
addi $t0, $a0, 0 # initialise $t0 (current pointer) to lower bound
addi $t1, $a1, 0 # initialise $t1 (add of end of array) to upper bound
Loop:
slt $t4, $t1, $t0
bne $t4, $zero, End # branch to end if upper < lower
lw, $t3, 0($t0) # store the content of the lower array pointer, ERROR: t0 should be used not a0
slt $t4, $t3, $t2 # if current ($t3) < min ($t2), store 1 in $t4
beq $t4, $zero, LoopEnd # if it is 0, go to LoopEnd
addi $t2, $t3, 0 # store content ($t3) as minimum ($t2)
addi $v0, $t0, 0 # store the address of min
LoopEnd:
addi $t0, $t0, 4 # increments current pointer lower bound
j Loop # Jump to loop
End:
jr $ra # return from this function
My code has two parts; the first part is making a function that takes in two numbers and return their products. I believe I did this part right.
The second part is where I'm not sure what's the problem is. In this part I need to make a function that find the factorial number, and within this function, I have to use the multiplication function which I made in the first part. Please have a look at my code and tell me what am I doing wrong.
.data
Fa_message: .asciiz "\nFAIL TEST\n"
Pa_message: .asciiz "\nPASS TEST\n"
number1: .word 4
number2: .word 5
KnownAnswers: .word 20
START: .word 16
.text
main:
# taking in the numbers for calculation.
lw $a0, number1 # $a0 =4
lw $a1, number2 # $a1 =5
lw $t0, KnownAnswers # $t0 =20
jal func_multiply # calling the mulyiply function
move $t4,$v0 # store the product for any further comparisons
bne $t0, $t4, FailT # did it fail the test?
beq $t0, $t4, PassT # did it pass the test?
func_multiply: # the mulyiply function
mul $v0, $a0, $a1 # $v0 = number1 * number2
jr $ra
FailT: # print "\nFAIL TEST\n"
li $v0,4
la $a0, Fa_message
syscall
PassT: # print "\nPASS TEST\n"
li $v0,4
la $a0, Pa_message
syscall
###---------------------(PART-2)-------------------
lw $a0, number1 # load the number for the factorial procedure
beq $a0, $zero, factorialDone # (if the number = 0), !0 = 1
mul $a1, $a1, $zero # initializing $a1
mul $a2, $a1, $zero # initializing $a2
addi $a1, $a0, -1 # $a1 = (the entered number - 1)
addi $a2, $a0, 0 # $a2 = the entered number
jal findfactorial
###
#Stop
li $v0, 10
syscall
findfactorial:
jal func_multiply # calling the mulyiply function # mul $v0, $a0, $a1 # $v0 = number1 * number2
move $t4,$v0 # store the product in t4 for any further usage
addi $a0, $a0, -1 # $a1 = $a1-1
addi $a1, $a0, -1
bne $a1, $zero, findfactorial # enter a loop if $a1 does not equal 0
jr $ra
factorialDone:
addi $v0, $v0, 1
syscall
The jal instruction modifies the $ra register. So if function A calls a function B, then A has to save and restore the value that $ra had when entering A so that it can return to the correct place. This is typically done using the stack as temporary storage.
You can push a register on the stack (save it) like this:
addi $sp, $sp, -4
sw $ra, ($sp)
And pop a register off the stack (restore it) like this:
lw $ra, ($sp)
addi $sp, $sp, 4
Then there's your findfactorial loop. You're discarding the result of all the previous iterations, so your result will always be 1*2 == 2. The loop ought to look something like this:
findfactorial:
jal func_multiply
move $a0,$v0
addi $a1, $a1, -1
bne $a1, $zero, findfactorial
This way you first multiply 4 by 3, then 12 by 2, etc.
There are some other isues in your code. For example, if you jump to FailT you don't immediately exit the program after printing the message - you just keep executing the code after PassT.
Also I'm not sure what this is supposed to do:
factorialDone:
addi $v0, $v0, 1
syscall
If you wanted to execute syscall 1 (print_int), then this is incorrect because it doesn't set up $v0 properly (it should be li $v0,1). And if you wanted this to print the result of your factorial computation then that's not going to happen, because you have a jr $ra right before that, so the only time you end up at factorialDone is if number1 contained 0. Also, you'd have to set up $a0 with the value you want to print.