dhilst

gas copy string n ;-)

#
# void
# mycpynstr (char *dst, char *src, int n)
# {
#     while (n--)
#         *dst++ = *src++;
# }
#
    .file    "cpystr.c"
    .text
.globl mycpynstr
    .type    cpynstr, @function
mycpynstr:
    pushl    %ebp
    movl    %esp, %ebp
    jmp    .L2             # goto (.L2)

#   *dst++ = *src++ at line 6
.L3:
    movl    12(%ebp), %eax #     move src to %eax  
    movzbl    (%eax), %edx #     %dl = (char *) %eax # (src) 
    movl    8(%ebp), %eax  #     move dst to %eax
    movb    %dl, (%eax)    #     *dst = *src
    addl    $1, 8(%ebp)    #     src++ 
    addl    $1, 12(%ebp)   #     dst++ 

# while (n--) at line 5
.L2:
    cmpl    $0, 16(%ebp)   #   if (n != 0) 
    setne    %al           #     %al = 1
    subl    $1, 16(%ebp)   #   n--
    testb    %al, %al      #   if (%al)    
    jne    .L3             #     goto (.L3)
    popl    %ebp           #   else
    ret                    #     return

    .size    mycpynstr, .-mycpynstr
    .ident    "GCC: (GNU) 4.5.1"
    .section    .note.GNU-stack,"",@progbits
I made this with `gcc -S cpystr.c' where cpystr.c contains the mycpynfunction
defined as in first eight lines in this file. Then I open the file cpystr.s
created by gcc and add the coments. Nothing more was changed.
The comments tell in C language what is happening. But I not sure if
every comment is exactly right... its just how I understand the code. The
comments start with `#' character and extends to the end of line.
Cheers :-)