Hi Stefan,
It's hard to tell without seeing how you coded the function that compare
values inside "data_items".
But try out the following:
data_items:
.int 34,67,34,222,45,75,38,19,29,39,100,0
.section .text
.globl _start
_start:
mov $0, %edi
/* Load the first byte */
mov data_items(,%edi,4), %eax
movl %eax, %ebx
call GetMax
[....]
.type GetMax, @function
GetMax:
/* Return after hitting the end(e.g. 0) */
cmp $0, %eax
je Return
/* else increment the pointer and load next value */
inc %edi
mov data_items(,%edi,4), %eax
/* Restart looping if the current number is <= to the biggest
recorded so far */
cmp %ebx, %eax
jle GetMax
/* else, record the new max value and restart looping */
mov %eax, %ebx
jmp GetMax
ret
--
Makhtar
On Tuesday 25 November 2008 17:01:56 you wrote:
> Today's Topics:
>
> 1. problem with maximum (Stefan Ciobaca)
> Message: 1
> Date: Sat, 22 Nov 2008 22:48:17 +0100
> From: "Stefan Ciobaca" <[EMAIL PROTECTED]>
> Subject: [Pgubook-readers] problem with maximum
> To: [email protected]
> Message-ID:
> <[EMAIL PROTECTED]>
> Content-Type: text/plain; charset=ISO-8859-1
>
> Hi!
>
> I have just started to read the book but I have a problem with the first
> real program in the book (that computes the maximum value from an
> array) -- it always outputs 0.
>
> In fact, I have isolated the problem to a couple of instructions. Here is
> my code
>
> .section .data
>
> data_items:
> .long 34,67,34,222,45,75,38,19,29,39,100,0
>
> .section .text
>
> .globl _start
> _start:
> movl data_items, %eax
> movl %eax, %ebx
> movl $1, %eax
> int $0x80
>
> This code exits with error code 0.
>
> However, if instead of
> movl data_items, %eax
> movl %eax, %ebx
> I do
> movl data_items, %ebx
>
> it exits with the expected error code 34.
>
> Does anyone have any idea what's wrong?
>
> Stefan Ciobaca
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