X-Authentication-Warning: delorie.com: mail set sender to djgpp-bounces using -f
Date: Tue, 01 Nov 2005 23:35:11 +0100
From: Pafo007 <"Pafo007 at wanadoo dot fr"@unknown.addr>
User-Agent: Mozilla Thunderbird 1.0 (Windows/20041206)
X-Accept-Language: fr, en
MIME-Version: 1.0
Newsgroups: comp.os.msdos.djgpp
Subject: Re: Why the call instruction points 2 bytes before to the real start
 sub-routine ?
References: <003501c5df1c$b3f4a440$2432a8c0 AT dcueva>
In-Reply-To: <003501c5df1c$b3f4a440$2432a8c0@dcueva>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Content-Transfer-Encoding: 8bit
Lines: 36
Message-ID: <4367ee3f$0$1729$8fcfb975@news.wanadoo.fr>
Organization: les newsgroups par Wanadoo
NNTP-Posting-Date: 01 Nov 2005 23:37:52 CET
NNTP-Posting-Host: 82.124.255.112
X-Trace: 1130884672 news.wanadoo.fr 1729 82.124.255.112:2975
X-Complaints-To: abuse AT wanadoo DOT fr
To: djgpp AT delorie DOT com
DJ-Gateway: from newsgroup comp.os.msdos.djgpp
Reply-To: djgpp AT delorie DOT com

Ouch! Going to 32bits mode isn't a easy thing: you have to build a GDT, 
to load GDTR with LGDT intruction, to set bit0 of CR0 register and to 
jump to your code in a 32bits segment... That's a hard way if you 
haven't read anything about it!
Perhaps should you try this:
http://www.osdever.net/tutorials/pmodetuts/all_pm_tuts.zip?the_id=36
That's a 17 chapter book about protected mode...


Diego Cueva a écrit :
> Thanks for your response.
> 
> Now I am using a 32 bit disassembler:
> 
> 00000000  90                nop
> 00000001  E80B000000        call 0x11
> 00000006  66BE5C01          mov si,0x15c
> 0000000A  E834000000        call 0x43
> 0000000F  CD20              int 0x20
> 00000011  6650              push ax
> 00000013  6653              push bx
> 00000015  6651              push cx
> 00000017  6652              push dx
> 00000019  B406              mov ah,0x6
> 0000001B  B000              mov al,0x0
> 0000001D  B500              mov ch,0x0
> 
> This dis-assembled code is correct, but when I run the program does not
> work fine. 
> 
> The program act as a 16 bit code, this mean that the 1st CALL
> instruction, jump to 010F. In other words, this compiled program only
> execute:
>     100. - NOP
>     101. - CALL    010F (jump really to 10F not to 0x11)
>     10F. - INT 0x20   :(   That's all.