Trouble creating an array loop in Y86 Assembly - arrays

Question

I need to create a program that sorts an array of integers into ascending order. Simple enough problem in C, and the code is given to us.
void bubble(int *data, int count)
{
int i, last;
for(last = count‐1; last>0;last‐‐)
{
for(i=0;i<last;i++)
if
(data[i+1] < data[i])
{
/* Swap adjacent elements */
int t=data[i+1];
data[i+1]=data[i];
data[i]=t;
}
}
}
but when I try to implement it into assembly, I get either
Error on line 90: Invalid line
Line 90, Byte 0x00d0: .comm *data,20,4 //data = memory location
or, if I comment that line out (I don't think I should) I get this
Error on line 39: Expecting ')'
Line 39, Byte 0x005a: mrmovl (%edx,%ebx,4),%eax //%eax = data[i]
Error on line 41: Expecting ')'
Line 41, Byte 0x0066: mrmovl 4(%edx,%ebx,4),%edi //%edi = data[i++]
Error on line 46: Expecting ')'
Line 46, Byte 0x0073: mrmovl 4(%edx,%ebx,4),%edi //%edi = data[i++]
Error on line 47: Expecting ')'
Line 47, Byte 0x0079: rmmovl %edi, (%edx,%ebx,4) //data[i] = data[i++]
Error on line 48: Expecting ')'
Line 48, Byte 0x007f: rmmovl %eax, 4(%edx,%ebx,4) //data[i++] = data[i]
The following is my code as it stands:
.pos 0
init: irmovl Stack, %esp //Set up stack pointer
irmovl Stack, %ebp //Set up base pointer
call main //call main program
halt //Terminate program
bubble: pushl %ebp //setup
rrmovl %esp, %ebp
pushl %edx //declaring *data
mrmovl 8(%ebp), %edx
pushl %ecx //declaring count
mrmovl 12(%ebp), %ecx
pushl %ebx //declaring i
pushl %esi //declaring last
pushl %edi
pushl %eax
irmovl $1, %edi //%edi = 1
rrmovl %ecx,%esi //last=count
subl %edi,%esi //last--
L1:
irmovl $0, %edi //%edi = 0
subl %edi,%esi //last -= 0
jle L9 //ends loop if last <= 0
irmovl $0, %ebx //i = 0
L2:
rrmovl %ebx, %edi //%edi = copy of i
subl %esi,%edi //%edi = i-last
jge L8 //ends loop if i >= last
mrmovl (%edx,%ebx,4),%eax //%eax = data[i]
irmovl $1, %edi //%edi = 1
mrmovl 4(%edx,%ebx,4),%edi //%edi = data[i++]
subl %eax,%edi //%edi = data[i++]-data[i]
jge L7 //cancel if statement if data[i++]>=data[i]
mrmovl 4(%edx,%ebx,4),%edi //%edi = data[i++]
rmmovl %edi, (%edx,%ebx,4) //data[i] = data[i++]
rmmovl %eax, 4(%edx,%ebx,4) //data[i++] = data[i]
L7:
irmovl $1, %edi //%edi = 1
addl %edi,%ebx //i++
jmp L2 //go to beginning of loop
L8:
irmovl $1, %edi //%edi = 1
subl %edi,%esi //last--
jmp L1
L9:
popl %ebx //finish
popl %esi
popl %edi
popl %eax
popl %ebp
ret
main: pushl %ebp //setup
rrmovl %esp, %ebp
pushl %ebx //declaring *data
mrmovl data, %ebx
pushl %esi //declaring count
mrmovl count, %esi
rmmovl %ebx, (%esp) //move data to be used by bubble
rmmovl %esi, 4(%esp) //move count to be used by bubble
call bubble
popl %ebx //finish
popl %esi
popl %ebp
ret
.comm data,20,4 //data = memory location
.align 4
count: .long 5 //count = memory location
data: .long 2 //data array assignment
.long 1
.long 3
.long 5
.long 4
.pos 0x200
Stack: .long 0

Answer 1

y86 does not support the full x86 effective address syntax with the index and scale, it only allows displacement(base). You have to perform the address calculation yourself.
The y86 assembler doesn't support .comm either, just define your data using .long