Re: gas and gcc

Article View: comp.lang.asm.x86

Article #154

#154

From: Míla Kuchta
Date: Sat, 24 Nov 2001 18:52

65 lines
2444 bytes

Hello,

In alt.lang.asm Frank Kotler <fbkotler@ne.mediaone.net> wrote:
> Martin Cote wrote:
> 
>> extern write_char(char);
>> ----------------------------------
>> ..globl write_char
>> 
>> write_char:
>>  pushl %ebp
>>  movl  %esp,%ebp
> 
> push ebx

no

> 
>>  movl  $4,%eax
>>  xorl  %ebx,%ebx
>>  incl  %ebx
>>  movl  4(%esp),%ecx
>>  movl  %ecx,char
>>  leal  char,%ecx
>>  xorl  %edx,%edx
>>  incl  %edx
>>  int   $0x80
> 
> pop ebx

no again

That's simply because there are many mistakes.

1. Your function is not register safe.
2. The first parametr isn't 4(%esp), but 8(%ebp) (that's why you are
saving %esp to %ebp). 4(%ebp) is return address.

Here is fair copy.

.globl write_char

write_char:
	pushl	%ebp
	movl	%esp, %ebp

	pusha	# 1

	movl	$4, %eax
	xorl	%ebx, %ebx
	incl	%ebx
	leal	8(%ebp), %ecx # 2
	xorl	%edx, %edx
	incl	%edx
	int	$0x80

	popa	# 1

	leave
	ret

--
Regards from

Mila Kuchta

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From: Míla Kuchta <mila.kuchta@atlas.cz>
Newsgroups: comp.lang.asm.x86,alt.lang.asm,gnu.gcc
Subject: Re: gas and gcc
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