function in mips that calculates the absolute value [duplicate] - function

This question already has answers here:
Integer absolute value in MIPS?
(5 answers)
Closed 2 years ago.
hello i have an exercise in mips that must call a function to calculates the absolute value of a number
i have write 2 codes but if you have any other solution write it
.data
message:.asciiz "give number: "
.text
main:
li $v0, 4
la $a0, message
syscall
li $v0, 5
syscall
add $t1, $v0, $zero
jal absolute
add $v0,$t2,$zero
li $v0, 1
syscall
li $v0, 10
syscall
absolute: ori $t2,$t1,0 #copy r1 into r2
slt $t3,$t1, $zero #is value < 0 ?
beq $t3,$zero,gg #if r1 is positive, skip next inst
sub $t2,$zero, $t0 #r2 = 0 - r1
jr $ra
gg:
#t2
and the second code is this
.data
question: .asciiz "give number"
.text
main:
li $v0, 4
la $a0, question
syscall
li $v0, 5
syscall
jal absolute
li $v0, 1
syscall
li $v1, 1
syscall
li $v0, 10
syscall
absolute:
slti $t0,$a0,0
bne $t0,$zero,g1
add $v0,$a0,$zero
jr $ra
g1:
sub $t2,$a0,$a0
sub $v1,$t2,$a0
j absolute

Try this:
.data
message: .asciiz "Enter the number: "
.text
.globl main
main:
# print message
li $v0, 4
la $a0, message
syscall
# read integer
li $v0, 5
syscall
slt $t0, $v0, $0 # $t0 = ( $v0 < 0 ? 1 : 0 )
bne $t0, $0, NEGATIVE # if($t0 != 0) goto NEGATIVE
j POSITIVE # goto POSITIVE (and dose nothing)
NEGATIVE:
# ~$v0 + 1
nor $v0, $v0, $0 # NOR with zero = NOT
addi $v0, $v0, 1 # $v0 =+ 1
POSITIVE:
# print $v0
move $a0, $v0
li $v0, 1
syscall
# print new line '\n'
li $v0, 11
addi $a0, $0, 10
syscall
jr $ra
Test:
Enter the number: 10
10
Enter the number: -5
5

Related

Getting Memory out of bounds exception while running code in QTSPIM

I am trying an array to save i * j values and print the values from array.
I have two loops loop1, loop2, where loop1 takes i and loop2 takes on j.
I am trying to save the i * j in a myarray which is space datatype.
I am getting exception Memory address out of bounds and unable to find whats the error.
.data
myarray: .space 10000
n: .word 1
space_line: .asciiz " "
new_line: .asciiz "\n"
.text
.globl main
main:
lw $a0, n
la $a1, myarray
li $a2, -1 #row
li $t0, 0
li $t2, 0
loop1:
addi $a2, $a2,1
bge $a2, $a0, print_loop
li $a3, 0 #column
j loop2
loop2:
bge $a3, $a0, loop1
#multiply a2 and a3
mul $t1, $a2, $a3
sw $t1, 0($a1)
addu $a1, $a1,4
addi $a3, $a3,1
j loop2
print_loop:
mul $t3, $a0, $a0
bge $t0, $t3, exit
li $v0, 4
lw $a0, myarray($t2)
syscall
li $v0, 4
lw $a0, space_line
syscall
rem $t4, $t3, $a0
beqz $t4, newline
addu $t2, $t2, 4
addi $t0, $t0, 1
j print_loop
newline:
li $v0, 4
lw $a0, myarray($t2)
syscall
exit:
# Done, terminate program.
li $v0, 10
syscall # all done!
.end main
For n =4,i am expecting the output in console as
0 0 0 0
0 1 2 3
0 2 4 6
0 4 8 12
You can find this problem by single stepping in the debugger.  Start with the smallest possible input, like n=1 as you're showing.  After each instruction, verify that it did what you want, and that it didn't do anything else except what you wanted.
Here's a hint: Pay attention to the difference between la and lw.  Also, If you want to put syscalls in the middle of your code or loops, then avoid the $a0 and $v0 registers for your own variables — just makes things easier/better.

How to count the number of spaces in MIPS?

I need to write a program in which the output will be the number of sentences and average number of words. The code is working perfectly for counting the sentences, but for the second task, it doesn't work. I'm using branch if equal with the current char and the register in which I've declared the ascii value for space which is 32. With this code, the output for the average words is the total number of characters from the whole input. I can't understand how it can count every character when the beq is clearly incorrect. (I've also tried with emptySpace: .asciiz " ", but it's not working)
This is what I got so far:
.data
str_input: .space 256
dot: .asciiz "."
msg1: .asciiz "Number of sentences: "
msg2: .asciiz "\nAverage number of words: "
.text
li $v0, 8 #read string
la $a0, str_input #address of str_input vo $a0
li $a1, 256 #256 max
la $a2, dot
lb $a2, 0($a2)
li $a3, 32
syscall
addi $t4, $zero, 0 #counter for words
addi $t5, $zero, 0 #counter for sentences
or $t0, $a0, $zero #$t0 pointer to array
start:
lb $t1, 0($t0) #$t1 current char
beqz $t1, end
jal check
addiu $t0, $t0, 1
j start
chech:
beq $t1, $a2, IsDot
beq $t1, $a3, IsEmptySpace
IsDot:
addi $t5, $t5, 1
jr $ra
IsEmptySpace:
addi $t4, $t4, 1
jr $ra
end:
la $a0, msg1 #address of msg1 in $a0
li $v0, 4 #load string in $v0
syscall
add $a0, $t5, $zero
li $v0, 1
syscall #print number of sentences
addi $t4, $t4, 1 #add the last word
div $t4, $t5 #divide number of words with number of sentences
mflo $t6
la $a0, msg2 #address of msg2
li $v0, 4 #load string in $v0
syscall
add $a0, $t6, $zero
li $v0, 1
syscall

Replacing repeated consecutive characters with X

I have some trouble with my code.
I need this in/output on the console.
Input String : aaabcccdeefggg
Input char: X
Replace:XXXbXXXdXXfXXX <--I want this output
But i get this output-->XXabXXcdXefXXg
I dont know where the bug is, i am searching for hours for this bug.
.data
enterString: .asciiz "Input String > "
enterChar: .asciiz "Input char> "
changedString: .asciiz "\nReplace: "
numberOfAdditions: .asciiz "\Total Replaces: "
userInput: .space 555
.text
main:
li $v0, 4
la $a0, enterString
syscall
li $v0, 8
la $a0, userInput
li $a1, 554
syscall
li $v0,4
la $a0,enterChar
syscall
li $v0,12
syscall
move $t5,$v0 # $t0 = character to be replaced
li $t0, 0
li $t1, 1
j findDoubleCharacters
findDoubleCharacters:
lbu $s0, userInput( $t0 )
lbu $s1, userInput( $t1 )
addi $t0, $t0, 1
addi $t1, $t1, 1
beq $s0, $s1, found
beq $s1, 0, end
j findDoubleCharacters
found:
subi $t0, $t0, 1
subi $t1, $t1, 1
sb $t5, userInput($t0)
addi $s2, $s2, 1
j findDoubleCharacters
end:
li $v0, 4
la $a0, changedString
syscall
li $v0, 4
la $a0, userInput
syscall
li $v0, 4
la $a0, numberOfAdditions
syscall
li $v0, 1
move $a0, $s2
syscall
...

Trouble with MIPS array

i'm trying to write some code that take as input integers and strings, stores them into an array and then prints them in order (int-string, int-string etc.). I will eventually add some sorting code for the integer, when i get this to work. The problem is i can't get the code to work right, i can't manage to have the output come out correctly. I'm assuming the problem lies in the array, since i'm not sure how it is supposed to work (MIPS is definitely not my forte). The code is the following:
.data
array: .space 400 #array
in_name:
.asciiz "\nInsert name: "
in_date:
.asciiz "\nInsert date (mmdd): "
appt:
.asciiz "\nList: "
spaz: .asciiz " "
.text
main:
la $s0, array #load array in s0
addi $t0, $zero, 0 #t0=0 counter
addi $s1, $zero, 0 #s1=0 array size counter
j Input
Input:
li $v0, 4
la $a0, in_date
syscall #ask date
li $v0, 5
syscall #read date
add $t1, $zero, $t0 #offset in t1
add $t1, $t1, $t1 #t1*2
add $t1, $t1, $t1 #t1*4
add $s2, $t1, $s0 #array with offset in s2
sw $v0, 0($s2) #save date
addi $t0, $t0, 1 #t0++
addi $s1, $s1, 1 #array size counter +1
li $v0, 4
la $a0, in_name
syscall #ask name
li $a0, 4
li $v0, 9
syscall #space for new word (4bytes)
la $a0, array
li $a1, 4
li $v0, 8
syscall #read name
add $t1, $zero, $t0 #offset in t1
add $t1, $t1, $t1 #t1*2
add $t1, $t1, $t1 #t1*4
add $s2, $t1, $s0 #array with offset in s2
sw $v0, 0($s2) #save name
addi $s1, $s1, 1 #array size counter +1
addi $t0, $t0, 1 #t0++
beq $s1, 10, print #if array size=10 go to print
j Input #start over until s1=10
print:
la $a0, appt
li $v0, 4
syscall #print list
addi $t0, $zero, 0 #t0=0 counter
res:
add $t1, $zero, $t0 #offset in t1
add $t1, $t1, $t1 #t1*2
add $t1, $t1, $t1 #t1*4
add $s2, $t1, $s0 #array with offset in s2
lw $a0, 0($s2) #load date
li $v0, 1
syscall #print data
addi $t0, $t0, 1 #t0++
la $a0, spaz #load space
li $v0, 4
syscall #print space
add $t1, $zero, $t0 #offset in t1
add $t1, $t1, $t1 #t1*2
add $t1, $t1, $t1 #t1*4
add $s2, $t1, $s0 #array with offset in s2
lw $a0, 0($s2) #load name
li $v0, 4
syscall #print name
addi $t0, $t0, 1 #t0++
la $a0, spaz
syscall #print space
addi $t0, $t0, 1 #t0++ counter
bne $t0, $s1, res #start over until t0=s1
j end
end:
li $v0, 10
syscall #the end
Depending on which program i use to test it i get an error or the program ends correctly but with a wrong output (just some numbers).
Can someone point out to me how should i correct it to make it work properly?
Thanks
I changed the program a little. I created 2 arrays for numbers and strings. As I read date and name I save them to num_array and str_array respectively. This makes it easier to deal with addressing, and might be easier for processing later. Comments in the code should be helpful.
.data
num_array: .space 400 #array
str_array: .space 400
in_name: .asciiz "\nInsert name: "
in_date: .asciiz "\nInsert date (mmdd): "
appt: .asciiz "\nList: "
spaz: .asciiz " "
.text
main:
la $s0, num_array #load array in s0
la $s1, str_array
addi $t0, $zero, 0 #t0=0 counter
addi $s2, $zero, 0 #s1=0 array size counter
j Input
Input:
# prompt for date
li $v0, 4
la $a0, in_date
syscall
# read date
li $v0, 5
syscall
# store date in the num_array
sw $v0, 0($s0)
# increment counter and move to next position in the array
addi $t0, $t0, 1
addi $s2, $s2, 1
addi $s0, $s0, 4
# prompt for name
li $v0, 4
la $a0, in_name
syscall #ask name
# store name (max 4 bytes) to str_array ($s1)
move $a0, $s1
li $a1, 4
li $v0, 8
syscall #read name
# move to the beginnig of next string in $s1
# increment by 4 because length of each input word is 4
addi $s1, $s1, 4
beq $s2, 10, print #if array size=10 go to print
j Input #start over until s1=10
print:
# print "List:"
la $a0, appt
li $v0, 4
syscall #print list
addi $t0, $zero, 0 #t0=0 counter
la $s0, num_array # address of num_array
la $s1, str_array # address of str_array
res:
# get number from num_array and print it
lw $a0, 0($s0)
li $v0, 1
syscall
# move to the next element, increment by 4 because numbers take 1 word = 4 bytes
addi $s0, $s0, 4
# get string from str_array and print it
la $a0, 0($s1)
li $v0, 4
syscall
# print space
la $a0, 32
li $v0, 11
syscall
# move to the next element, increment by 4 because strs have 4 bytes length (in your case)
addi $s1, $s1, 4
# increment loop counter
addi $t0, $t0, 1
blt $t0, $s2, res # $s2 is size of the array
end:
li $v0, 10
syscall #the end
Here is the output:
Insert date (mmdd): 1201
Insert name: aaa
Insert date (mmdd): 1202
Insert name: bbb
Insert date (mmdd): 1203
Insert name: ccc
Insert date (mmdd): 1204
Insert name: ddd
Insert date (mmdd): 1205
Insert name: eee
Insert date (mmdd): 1206
Insert name: fff
Insert date (mmdd): 1207
Insert name: ggg
Insert date (mmdd): 1208
Insert name: hhh
Insert date (mmdd): 1209
Insert name: iii
Insert date (mmdd): 1210
Insert name: jjj
List: 1201aaa 1202bbb 1203ccc 1204ddd 1205eee 1206fff 1207ggg 1208hhh 1209iii 1210jjj
-- program is finished running --

MIPS branching always the same

So with this MIPS code I'm trying to get a users input of a tree size they would like and the output is the cost. 199 for > 8, 99 >= 6, 69 >= 3, 39 >= 0, and just a phrase saying positive only for a negative input.
My problem is that no matter the input, the program always spits out 69, whats wrong?
#data declarations: declare variable names used in program, storage allocated in RAM
.data
msg1: .asciiz "Enter the height of a tree to purchase: "
msg21: .asciiz "The cost: "
msg22: .asciiz " dollars\n"
msg3: .asciiz "\n"
msgNeg: .asciiz "Please enter a positive integer for the tree height.\n"
big: .word 8
med: .word 6
small: .word 3
negative: .word 0
#The program begins after .text
.text
main:
#Prints first line and receives input
la $a0, msg1
li $v0, 4
syscall
li $v0, 5
syscall
la $a0, msg3
li $v0, 4
syscall
#Stores user input in parameter variable
move $a0, $v0
#Calls cost function to determine cost
addi $sp, $sp, -4
sw $ra, 0($sp)
jal cost
lw $ra, 0($sp)
addi $sp, $sp, 4
#stores returned value to temporary register
move $t0, $v0
#Prints out the cost of the tree
la $a0, msg21
li $v0, 4
syscall
move $a0, $t0
li $v0, 1
syscall
la $a0, msg22
li $v0, 4
syscall
#return
jr $ra
cost:
#finds the range of the user value
la $t6, small
lw $t7, 0($t6)
bge $a0, $t7, smTree
nop
la $t6, med
lw $t7, 0($t6)
bge $a0, $t7, medTree
nop
la $t6, big
lw $t7, 0($t6)
bgt $a0, $t7, bigTree
nop
la $t6, negative
lw $t7, 0($t6)
blt $a0, $t7, negTree
nop
#else statement, returns 39
li $v0, 39
jr $ra
bigTree:
#first branch, returns 199
li $v0, 199
jr $ra
medTree:
#second branch, returns 99
li $v0, 99
jr $ra
smTree:
#third branch, returns 69
li $v0, 69
jr $ra
negTree:
#fourth branch, returns a phrase
la $a0, msgNeg
li $v0, 4
syscall
jr $ra
When you're reading the user's number:
li $v0, 5
syscall
la $a0, msg3
li $v0, 4
syscall
#Stores user input in parameter variable
move $a0, $v0
$v0 will no longer hold the user's value. It has been overwritten with 4, which corresponds to the case that returns a cost of 69. You'll have to copy $v0 to another temporary register right after syscall 5.
Also, the logic of cost is currently like this:
if (value >= 3)
return 69;
if (value >= 6)
return 99;
if (value >= 8)
return 199;
So any value >= 3 will return 69, and the larger cases will never be checked. You can just change the order to fix it:
if (value >= 8)
return 199;
if (value >= 6)
return 99;
if (value >= 3)
return 69;