Traversing and averaging elements in an array MASM - c

Question

I am in a x86 masm class, and we have a project coming up that I do not understand. The TA and Professor are pretty much useless, I've been trying to get into contact with them for a week and no answer and no office hours. Anyways, I am supposed to calculate the average number of days per month over the span of 15 years. (2000-2015) We are also supposed to factor in leap year.
I wrote the program in C beforehand, and here is my code:
main()
{
double sum=0;
int dpm[12] = {31,28,31,30,31,30,31,31,30,31,30,31};
int i=0;
int j=0;
int months=0;
while(j<16)
{
while(i<12)
{
if(j==0 || j==4 || j==8 || j==12)
{
dpm[1]=29;
}
sum+=dpm[i];
dpm[1]=28;
months++;
i++;
}
j++;
}
printf("%.2f",sum/months);
}
(I realize using a for-loop would be best here, however while loops are easier to do in asm, so I used a while loop)
I don't understand assembly too well, but here is what I have so far:
.DATA
sum DWORD 0
months DWORD 0
dpm DWORD 31,28,31,30,31,30,31,31,30,31,30,31
elm DWORD 12
i WORD 0
j WORD 0
.CODE
main
mov eax, sum ; move sum to eax
lea esi, dpm ; move array to ebx
mov ecx, elm ; move no of elements to ecx
mov ax, j ; move j to ax
mov bx, i ; move i to bx
outterLoop:
cmp 15, ax ; compare 15 to i
jle innerloop ; jump to inner loop if it is less
innerLoop:
cmp 11, bx ; compare 11 to j
jle checkLeap ; jump to checkleap if it is less
inc ax ; incremement j
checkLeap:
cmp 0, bx ; if j is 0
je leap ; go to leap year function
cmp 4, bx
je leap
cmp 8, bx
je leap
cmp 12, bx
je leap
jne updates ; if not, go to updates fn
leap:
add esi, 4 ; go to second element in array "february"
mov 29, esi ; make feb 29 instead of 28
updates:
add eax, [esi] ; add element to sum
add esi, 4 ; increment array
; inc months
mov ; here I would make second element of array 28
inc bx ; increment i
I do not know if I am on the right track, and would like guidance, advice. Thank you

Answer 1

When comparing with an immediate value you need to put the number last. (Correct it 7 times)
cmp ax, 15 ; compare 15 to i
To change the length of february in the list use
mov dword [esi], 29 ; make feb 29 instead of 28
Same thing to reset it
mov dword [esi], 28 ; here I would make second element of array 28
Since you have put your j index in the AX register you need to place the sum in a register different from EAX. Remember that AX is just the low 16 bits of EAX.
The next code needs an additional jump. Now it ALWAYS performs innerLoop
cmp ax,15 ; compare 15 to i
jle innerloop ; jump to inner loop if it is less
innerLoop:

Answer 2

this code is working and giving correct output in edx register.
comment below if you want me to add comments to this code.
i implemented your logic with necessary changes, the thing is you are implementing that incorrectly
Include irvine32.inc
.data
; (31==1Fh)(30==1Eh)(28==1Ch)(29==1Dh)
dpm dword 1Fh,1Ch,1Fh,1Eh,1Fh,1Eh,1Fh,1Fh,1Eh,1Fh,1Eh,1Fh
countj dword ?
temp dword ?
temp1 dword ?
.code
Main Proc
; [instr] [destor opp1] [addtio instr] [source orOpp2] ;comment
mov ecx, 15 ;intializing to max value of j
mov esi, offset dpm ;storing offset of dpm to esi
mov edx, 0 ;intializing sum to 0
mov ebx, 0 ;intializing counter to 0
mov eax, 0 ;intializing counter to 0
loopj: ;loop of j
mov countj, ecx ;storing count of j
mov ecx, 12 ;intializing to max value of i
loopi: ;loop of i
inc ebx
mov eax, countj
;start of if statement:
cmp eax, 1 ;jump if j is 1
je IfJConTrueStart
cmp eax, 5 ;jump if j is 5
je IfJConTrueStart
cmp eax, 9 ;jump if j is 9
je IfJConTrueStart
cmp eax, 13 ;jump if j is 13
je IfJConTrueStart
;29
JConMid:
call dumpregs
mov temp1, edx
mov eax, ecx
mov temp, type dpm
mul temp
add esi, eax
sub esi, temp
call dumpregs
mov edx, temp1
add edx, [esi]
call dumpregs
sub esi, eax
add esi, temp
call dumpregs
JConEnd:
loop loopi
mov ecx, countj
loop loopj
jmp skipIfJConTrue
IfJConTrueStart:
cmp ecx, 2
je IfJConTrueMid
jmp JConMid
IfJConTrueMid:
add edx, 1Dh
jmp JConEnd
skipIfJConTrue:
call dumpregs
Exit
Main endp
End main