MIPS: determine if a list of tests passes
I am writing a MiPS program that will review a list of 15 tests. And it will be entered from the terminal. Well, the pass criterion is a score of 50. Outs to the terminal will include the grades in each category and the number of passing and unsuccessful students. with input and output hints ... Below is a program that I wrote, but it didn't work .... Please, I need .... I don't know if I'm doing it wrong ..
.globl main
.text
main: li $ t0, 0 #counter for passing la $ t1, pass #pointer for array pass
li $ t2, 0 #counter for unsuccessful la $ t3, fail #pointer for array pass li $ t4, 0 # for the whole counter li $ t5, 0 li $ t6, 0
loop: li $ v0, 4 # system call for print line la $ a0, prompt line #load syscall
li $v0, 5 #system call for read integer
syscall #read integer
bltu $v0, 50, else #if $v0 < 50 branch to else (failing grade)
sw $v0, 0($t1) #store word in pass array
addi $t1, $t1, 4 #t1 = t1 + 4 (increment pass pointer)
addi $t0, $t0, 1 #t0 = t0 + 1 (increment pass counter)
b l_end #branch over else statement
more: sw $ v0, 0 ($ t3) #store word in fail array addi $ t3, $ t3, 4 # t3 = t3 + 4 (increment error pointer) addi $ t2, $ t2, 1 # t1 = t1 + 1 (increment counter counter)
l_end: addi $ t4, $ t4, 1 #increment total counter bltu $ t4, 15, loop #if t4 <= 15 branches per loop
amount of output
li $v0, 4 #system call for print string
la $a0, o_pasc #load string
syscall #output "Number of Passing Scores:
la $v0, 1 #system call for print integer
add $a0, $t0, 0 #load value of pass counter into $a0
syscall #output value
li $v0, 4 #system call for print string
la $a0, o_fasc #load string
syscall #output "Number of Failing Scores: "
la $v0, 1 #system call for print string
add $a0, $t2, 0 #load value of fail counter into $a0
syscall #output value
transfer results
li $v0, 4 #setup output
la $a0, o_pass #setup text
syscall #output string o_pass
la $t1, pass #load address of pass pointer to t1
lw $a0, 0($t1) #load word at $t1 into $a0
li $v0, 1 #system call for print integer
loop_a: bleu $ t0, $ t5, lp_a_end #if t0 <= t5 branch to lp_a_end syscall #output single score
li $v0, 4 #system call for print string
la $a0, o_coma #load string
syscall #ouput comma and space
li $v0, 1 #setup output
addi $t1, $t1, 4 #move pointer down by 1 word
lw $a0, 0($t1) #move word at pointer into $a0
addi $t5, $t5, 1 #add 1 to counter
b loop_a #branch to top
lp_a_end:
withdrawal bad grades
la $t5, 0 #clear t5 (counter)
li $v0, 4 #setup output
la $a0, o_fail #setup text
syscall #output string o_fail
la $t3, fail #load address for fail pointer into $t3
lw $a0, 0($t3) #load word at mem addy $t3 into $a0
li $v0, 1 #system call for print integer
loop_b: bleu $ t2, $ t5, lp_b_end #if t2 <= t5 branch to lp_a_end syscall #output single score
li $v0, 4 #system call for print string
la $a0, o_coma #load string
syscall #output comma and space
li $v0, 1 #setup output
addi $t3, $t3, 4 #move pointer down by 1 word
lw $a0, 0($t3) #load word from mem addy $t3 to $a0
addi $t5, $t5, 1 #add 1 to counter
b loop_b #branch to top
lp_b_end:
end
li $v0, 4 #setup output
la $a0, o_brk #setup text
syscall #output line break
li $v0, 10 #loads 10 to $v0
syscall #ends program
"Deja vu is usually a glitch in the matrix"
Pretty sure I've seen this around:
MIPS Program for Missed / Failed Test Grades
EDIT . Some tips: try to simplify. Build your program piece by piece. For example, try to avoid system calls, use hardcoded inputs to test your comparison logic. Then go to syscalls. Are you using arrays correctly? I saw that you keep two separate counters to index the array and keep the number of elements inside it. I think it is error prone. Perhaps you should use a counter to index the array (multiplying by 4). Follow the link, I will be happy to help if in any doubt.
I don't like the SPIM simulator. I know that many universities use it for their courses, but I think this is a mistake as it is a very limited environment.
ANOTHER CHANGE (per "popular" demand) : I've been reading your code for a while and I've noticed some things.
-
You are loading values into registers for comparison to zero. Don't do this, use the $ zero register.
li $ t5.0
li $ t6.0
used in
bleu $t0,$t5,lp_a_end #if t0 <= t5 branch to lp_a_end
it should be
bleu $t0,$zero,lp_a_end
-
Using instructions
bltu $ v0, 50, else #if $ v0 <50 to another (unsuccessful class)
branch instructions have two registers and a label. Do not register, do, mark
Should be:
li $t5,50
bltu $v0,$t5,else
My guess is that you have a hard time over complicating system calls. Why do you think about your output when you can't make it work? In addition to this, once you start preparing for syscall, execute it. Don't put a branch instruction in the middle like in
la $t3, fail #load address for fail pointer into $t3
lw $a0, 0($t3) #load word at mem addy $t3 into $a0
li $v0, 1
loop_b: bleu $t2, $t5, lp_b_end #if t2 <= t5 branch to lp_a_end
syscall #output single score
It's pretty confusing. You might want to try something like:
#Is there anything to print in the array? If not, goto lp_b_end
bleu $t2,$zero,lp_b_end
#Ok, we know we are not pointing at an invalid position of the array.
la $t3, fail #load address for fail pointer into $t3
lw $a0, 0($t3) #load word at mem addy $t3 into $a0
li $v0, 1
syscall
Finally, try to preserve the convention when using system calls. For example, use registers $ a0 and $ v0 for system calls only. Don't use them for anything else. If you read an integer in $ v0, move it to $ t0 before doing anything else.
That's all I can think of right now. As someone said in the bug report (Rob Kennedy), try asking your instructor why he is getting paid (I'm not your instructor, just a helping hand).
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