Re: [Pgubook-readers] Pgubook-readers Digest, Vol 51, Issue 1

[Mike Eichler]

That's very strange, I copied and pasted your program, assembled it
and linked it and when i did 'echo $?' the result was 62.

On 07/11/15 17:00, address@hidden wrote:
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> 1. ending-address using base pointer addressing mode (William 
> Rodrigues) 2. Re: ending-address using base pointer addressing
> mode (Roger)
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Message: 1 Date: Fri, 6 Nov 2015 21:36:56 -0200 From: William
> Rodrigues <address@hidden> To: address@hidden 
> Subject: [Pgubook-readers] ending-address using base pointer 
> addressing mode Message-ID: 
> <address@hidden>
>
>
> 
Content-Type: text/plain; charset="utf-8"
> 
> Hi everyone, I'm William from Brazil; this is my first 
> participation on here. I am reading the 4th chapter from pgubook, 
> but at one exercise of the third I'm at some difficulty. The text 
> says to modify the maximum.s code and use an ending address rather 
> than the number 0 to know when to stop.
> 
> I tried this,
> 
> .section .data
> 
> data_items: .long 3,62,14,20,35,49,74,55,0
> 
> .section .text .globl _start _start: movl $data_items, %ecx     # 
> initialize %ecx with the address of data_items movl 4(%ecx), %ebx #
> go to base pointer addressing mode, trying to get the value 62. 
> movl $1, %eax int $0x80
> 
> If %ecx has the (pointer) address of data_items. So, why the
> return value was 0 instead of 62 or 35?
> 
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> 
> Message: 2 Date: Fri, 6 Nov 2015 21:53:07 -0500 From: Roger 
> <address@hidden> To: address@hidden Subject: 
> Re: [Pgubook-readers] ending-address using base pointer addressing 
> mode Message-ID: <address@hidden> 
> Content-Type: text/plain; charset=us-ascii
> 
>> On Fri, Nov 06, 2015 at 09:36:56PM -0200, William Rodrigues 
>> wrote: Hi everyone, I'm William from Brazil; this is my first 
>> participation on here. I am reading the 4th chapter from
>> pgubook, but at one exercise of the third I'm at some difficulty.
>> The text says to modify the maximum.s code and use an ending
>> address rather than the number 0 to know when to stop.
>> 
>> I tried this, **.section .data
>> 
>> data_items: ** .long 3,62,14,20,35,49,74,55,0
>> 
>> **.section .text **.globl _start _start: ** movl $data_items, 
>> %ecx******** # initialize %ecx with the address of data_items ** 
>> movl 4(%ecx), %ebx******************** # go to base pointer 
>> addressing mode, trying to get the value 62. ** movl $1, %eax ** 
>> int $0x80
>> 
>> If %ecx has the (pointer) address of data_items. So, why the 
>> return value was 0 instead of 62 or 35? Thanks.
> 
> If I'm not mistaken, there are some minor mistakes within the
> book, or code sections.  Typos I think.  You can either trace the
> code to find the error (as I did when I first read the book a
> decade ago), or search using Google to find the specific errors
> mentioned by others.
> 
> It is possible somebody has already compiled an errata listing by 
> now for this book!
> 
> Still, it is a great book, or great read, and you will not regret 
> reading, nor doing/performing each of the exercises as I have. Most
> programmers take little time to understand how using their C/C++
> routines use or effect the CPU.  On the flip, these programmers
> publish code by the handful on a daily basis.
>