Need help with Mips program, please

[kahad]

Hello!

I'm trying to type a thing in MIPS code. It takes two integers n and m. Both must be between 1 and 10 inclusive. It tests the numbers and complains until the numbers meet the requirements. It then computes 1^m + 2^m + …. + n^m. For example. should n=3 and m=2, the program will give back the integer 14. I'm trying the program right now assuming that m=10, but it's giving me strange results. I've been at it a while and I can't see what I'm doing wrong. With my luck, it's most likely something that's staring me in the face.

So, what am I doing wrong???

Thank you.

.text
          .globl main   
main:
          subu $sp,$sp,32   # stack frame is 32 bytes long
          sw   $ra,20($sp)  # save return address
          sw   $fp,16($sp)  # save frame pointer
          addu $fp,$sp,32   # set up frame pointer
	 li   $v0,4        # system call to print_inp
	 la   $a0,inp
          syscall
          li   $v0,5        # system call code for read_int
          syscall           # read an integer n from the console
          move $a2,$v0      # save n into $a2
          jal  checkn       # checks n
          move $t0,$v0      # store $v0 in tmp register
          li   $v0,4        # system call to print_string
          la   $a0,str
          syscall
          li   $v0,1        # system call to print_int
          move $a0,$t0
          syscall

          lw   $ra,20($sp)  # restore return address
          lw   $fp,16($sp)  # restore frame pointer
          addu $sp,$sp,32   # pop stack frame
          jr   $ra          # return to caller

          .data             # store string in data segment
inp:	 .asciiz "Please input the integer: "
errn:     .asciiz "please input an integer between 1 and 10 inclusive: "
errm:     .asciiz "please input an integer between 1 and 10 inclusive: "
str:      .asciiz "The result is "

          .text

checkn:   li   $t1,1          # puts 1 into $t1
          li   $t2,10         # puts 10 into $t2

          blt  $a2,$t1,errorn # jumps to errn if n is less than 1
          bgt  $a2,$t2,errorn # jumps to errn if n is more than 10
          j    getm

errorn:
          li   $v0,4        # system call to print_err
	 la   $a0,errn
          syscall
          li   $v0,5        # system call code for read_int
          syscall           # read a integer from the console
          move $a2,$v0      # save n into $a0
          j    checkn       # jumps to checkn

getm:     li   $v0,4        # system call code for read_int
          la   $a0, inp
          syscall
          li   $v0,5        # system call code for read_int
          syscall           # reads an integer m from the console
          move $a3,$v0      # saves m into $a3
          j  checkm         # checks m

checkm:   li   $t1,1          # puts 1 into $t1
          li   $t2,10         # puts 1o into $t2
          blt  $a3,$t1,errorm # jumps to err if m is less than 1
          bgt  $a3,$t2,errorm # jumps to err if m is more than 10
          j whatism

errorm:
	 li   $v0,4        # system call to print_err
	 la   $a0,errm
          syscall
          li   $v0,5        # system call code for read_int
          syscall           # read a integer from the console
          move $a3,$v0      # save m into $a3
          j    checkm       # jumps to checkm

whatism:  li  $t4,10
          beq $a3,$t4,ten

ten:
          subu $sp,$sp,32   # same as before
          sw   $ra,20($sp)
          sw   $fp,16($sp)
          addu $fp,$sp,32

          li   $t8,0        # set up minimun value of $a2
          
loopten:  blt  $a2,$t0,exit # if n < 1 , exit
          move $t7,$zero
          add  $t4,$t4,$a2
          mult $t4,$a2
          add  $t5,$t5,$t4
          mult $t5,$t4
          mult $t5,$t5
          mult $t5,$t4
          add  $t7,$t7,$t5
          move $v0,$t7
          sub  $a2,$a2,$t8  # decrement $a2
          j loopten         # loop unitl n < 1
exit:
          move $v0,$t7      # move result to $v0
          lw   $ra,20($sp)  # same as before
          lw   $fp,16($sp)
          addu $sp,$sp,32
          j    $ra

[Salem]

> I'm trying the program right now assuming that m=10
1E10 is getting pretty close to the limit of what you can store in a 32-bit signed integer (about 2.7E10).

If m <= 8 say works OK, then I'd say you're starting to see the effects of overflow on higher values for m.

[kahad]

I know that's not my problem. For n=1 and m=10, it's coming back with 22 when it should be coming back with 1.

Results for other ns.

n=2: Number given is 38, expected number is 1025.
n=3: Number given is 60, expected number is 60074

It seems that I can't edit my frist post anymore, so I'll just put the line change here.

I changed li $t8,0 to li $t8,1.

[Salem]

So how about posting a terminal session log, for those who don't have the means to run your program.
Just so we can all see the actual inputs and outputs you're testing with.

[kahad]

Where would I find the terminal session log? I'm using PCSpim to write this thing. Haven't used it much before.

[kahad]

Did some changing to the code. Now it's giving me 161051 as the answer regardless of what n is.

.text
          .globl main   
main:
          subu $sp,$sp,32   # stack frame is 32 bytes long
          sw   $ra,20($sp)  # save return address
          sw   $fp,16($sp)  # save frame pointer
          addu $fp,$sp,32   # set up frame pointer
	  li   $v0,4        # system call to print_inp
	  la   $a0,inp
          syscall
          li   $v0,5        # system call code for read_int
          syscall           # read an integer n from the console
          move $a2,$v0      # save n into $a2
          jal  checkn       # checks n
          move $t0,$v0      # store $v0 in tmp register
          li   $v0,4        # system call to print_string
          la   $a0,str
          syscall
          li   $v0,1        # system call to print_int
          move $a0,$t0
          syscall

          lw   $ra,20($sp)  # restore return address
          lw   $fp,16($sp)  # restore frame pointer
          addu $sp,$sp,32   # pop stack frame
          jr   $ra          # return to caller

          .data             # store string in data segment

inp:	  .asciiz "Please input the integer: "
errn:     .asciiz "please input an integer between 1 and 10 inclusive: "
errm:     .asciiz "please input an integer between 1 and 10 inclusive: "
str:      .asciiz "The result is "

          .text

checkn:   li   $t1,1          # puts 1 into $t1
          li   $t2,10         # puts 10 into $t2

          blt  $a2,$t1,errorn # jumps to errn if n is less than 1
          bgt  $a2,$t2,errorn # jumps to errn if n is more than 10
          j    getm

errorn:
          li   $v0,4        # system call to print_err
	  la   $a0,errn
          syscall
          li   $v0,5        # system call code for read_int
          syscall           # read a integer from the console
          move $a2,$v0      # save n into $a0
          j    checkn       # jumps to checkn

getm:     li   $v0,4        # system call code for read_int
          la   $a0, inp
          syscall
          li   $v0,5        # system call code for read_int
          syscall           # reads an integer m from the console
          move $a3,$v0      # saves m into $a3
          j  checkm         # checks m

checkm:   li   $t1,1          # puts 1 into $t1
          li   $t2,10         # puts 1o into $t2
          blt  $a3,$t1,errorm # jumps to err if m is less than 1
          bgt  $a3,$t2,errorm # jumps to err if m is more than 10
          j whatism

errorm:
	  li   $v0,4        # system call to print_err
	  la   $a0,errm
          syscall
          li   $v0,5        # system call code for read_int
          syscall           # read a integer from the console
          move $a3,$v0      # save m into $a3
          j    checkm       # jumps to checkm

whatism:  li  $t4,10
          beq $a3,$t4,ten

ten:
          subu $sp,$sp,32   # same as before
          sw   $ra,20($sp)
          sw   $fp,16($sp)
          addu $fp,$sp,32

          li   $t8,1        # set up minimun value of $a2
          
loopten:  
	  blt  $a2,$t0,exit # if n < 1 , exit
          addi $t7,0
          add  $t4,$t4,$a2
          mul  $t4,$t4,$a2
          add  $t5,$t5,$t4
          mul  $t5,$t5,$t4
          mul  $t5,$t5,$t5
          mul  $t5,$t5,$t4
          add  $t7,$t7,$t5
          move $v0,$t7
          sub  $a2,$a2,$t8  # decrement $a2
          j loopten         # loop unitl n < 1
exit:
          move $v0,$t7      # move result to $v0
          lw   $ra,20($sp)  # same as before
          lw   $fp,16($sp)
          addu $sp,$sp,32
          j    $ra