# wujialong 2018013418
    .pos 0
init:
    irmovl Stack,%esp
    irmovl Stack,%ebp
    call Main
    halt

    .align 4
# Source block 
src:
    .long 0x00a
    .long 0x0b0
    .long 0xc00
# Destination block 
dest:
    .long 0x111
    .long 0x222
    .long 0x333

Main:
    pushl %ebp
    rrmovl %esp,%ebp
    irmovl 0x3,%edx
    pushl %edx
    irmovl dest,%edx
    pushl %edx
    irmovl src,%edx
    pushl %edx                      # preparing paramters
    call swap_block                 # call function
    rrmovl %ebp,%esp
    popl %ebp  
    ret

swap_block:
    pushl %ebp
    rrmovl %esp,%ebp
    irmovl $0x10,%ecx
    subl %ecx,%esp
    pushl %esi
    pushl %edi
    irmovl $0x0,%ecx                # result = 0
    rmmovl %ecx,0xfffffff8(%ebp)    # -8(%ebp) = result
    jmp end
loop:
    mrmovl 0xfffffff8(%ebp),%ecx    # %ecx = result
    mrmovl 0x8(%ebp),%edx           
    mrmovl (%edx),%edx              # %edx = val
    xorl %edx,%ecx                  
    rmmovl %ecx,0xfffffff8(%ebp)    # result ^= val

    mrmovl 0x8(%ebp),%esi           # %esi = src
    mrmovl 0xc(%ebp),%edi           # %edi = dest
    rmxchg %ecx,(%esi)              # %ecx = *src
    rmxchg %edx,(%edi)              # %edx = *dest
    rrmovl %edx,%eax
    rrmovl %ecx,%edx
    rrmovl %eax,%ecx
    rmxchg %ecx,(%esi)
    rmxchg %edx,(%edi)              # swap(*src,*dest)       

    mrmovl 0x10(%ebp),%ecx          
    irmovl $0x1,%edx
    subl %edx,%ecx                  
    rmmovl %ecx,0x10(%ebp)          # len--

    mrmovl 0x8(%ebp),%eax           # %eax = src
    irmovl 0x4,%edx
    addl %eax,%edx
    rmmovl %edx,0x8(%ebp)           # src++

    mrmovl 0xc(%ebp),%eax           # %eax = dest
    irmovl 0x4,%edx
    addl %eax,%edx
    rmmovl %edx,0xc(%ebp)           # dest++
end:
    mrmovl 0x10(%ebp),%ecx
    irmovl $0x0,%edx
    subl %edx,%ecx
    jg loop                         # while(len>0)
    mrmovl 0xfffffff8(%ebp),%eax
    popl %edi
    popl %esi
    rrmovl %ebp,%esp
    popl %ebp  
    ret 

    .pos 0x500
Stack: