Linux assembly: Printing date and time

Hello, I'm trying to print date and time in linux usign GAS (GNU assembler). I started from a hello world code and I modified to show system date and time.

I'm stuck in two very basic errors I can't seem to find solution. Here's the code:

Code:

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##############################################################################
## getdatetime.s                                                                                                                        ##
##                                                                                                                                                        ##
## Compile with:                                                                                                                        ##
## as -o getdatetime.o getdatetime.s && ld -o getdatetime -O0 getdatetime.o        ##
##                                                                                                                                                        ##
##############################################################################
        .section .data
        .section .text
        .globl _start

_start:
        # call function to print date and time
        jmp                print_date_time

        ## terminate program via _exit () system call
        xorl        %eax,                %eax        # %eax = 0
        incl        %eax                                # %eax = 1 system call _exit ()
        xorl        %ebx,                %ebx        # %ebx = 0 normal program return code
        int                $0x80                                # execute system call _exit ()

## get system date and time and push it in stack: sec/min/hour/day/mon/year
print_date_time:
        movl        $78,                %eax        # getdatetime () system call
        int                $0x80                                # execute system call getdatetime ()
        addl        $0x48,                %eax        # convert to ascii value
        mov                %al,                %ecx        # print %al to see if we have something interesting in it (sec, min, hour, day, mon, year) or something
        movl        $1,                        %edx        # %edx = 1 = print length
        movl        $4,                        %eax        # write () system call
        int $0x80                                        # execute write () system call
        ret

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When I compile with

Code:

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as -o getdatetime.o getdatetime.s && ld -o getdatetime -O0 getdatetime.o

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It gives me an error:

Code:

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getdatetime.s: Assembler messages:
getdatetime.s:27: Error: suffix or operands invalid for `mov'

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Line 27 is:

Code:

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mov                %al,                %ecx        # print %al to see if we have something interesting in it (sec, min, hour, day, mon, year) or something

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Thanks for your attention.

I changed line 27 to use eax instead. Now it compiles. But I get segmentation fault when I run the program!

Code currently is:

Code:

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    .section .data
    .section .text
    .globl _start

_start:
    # call function to print date and time
    jmp        print_date_time

    ## terminate program via _exit () system call
    xorl    %eax,        %eax    # %eax = 0
    incl    %eax                # %eax = 1 system call _exit ()
    xorl    %ebx,        %ebx    # %ebx = 0 normal program return code
    int        $0x80                # execute system call _exit ()

## get system date and time and push it in stack: sec/min/hour/day/mon/year
print_date_time:
    movl    $0x78,        %eax    # getdatetime () system call
    int        $0x80                # execute system call getdatetime ()
    addl    $0x48,        %eax    # convert to ascii value
    movl    %eax,        %ecx    # print %eax to see if we have something interesting in it (sec, min, hour, day, mon, year) or something
    movl    $4,            %edx    # %edx = 1 = print length
    movl    $4,            %eax    # write () system call
    int $0x80                    # execute write () system call
    ret

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:(

mov is Intel syntax and movl is AT&T syntax
See http://asm.sourceforge.net/articles/linasm.html

With AT&T syntax, the fourth letter, just after mov can be b for a byte (8 bits), w for a word (16 bits), or l for a long word (32 bits).