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Date:	Tue, 01 Nov 2005 20:33:02 +0100
From:	Pafo007 <"Pafo007 at wanadoo dot fr"@unknown.addr>
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Newsgroups:	comp.os.msdos.djgpp
Subject:	Re: Why the call instruction points 2 bytes before to the real start
	sub-routine ?
References:	<003201c5df0c$20f5abe0$2432a8c0 AT dcueva>
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Hello.

In 32 bits mode, displacement is 4 bytes long: it is not 0B00 at address 
0101, but 0b000000 (look at 0000 at address 0104), whitch is 11 
(decimal) in intel-hexa. And it is relative to the address of the next 
instruction, whitch is 0106 and not 0104. And so 106 + 0B = 111 and not 
10F !

Hth


> 1579:0100 90            NOP
> 1579:0101 E80B00        CALL    010F
> 1579:0104 0000          ADD     [BX+SI],AL
> 1579:0106 66            DB      66
> 1579:0107 BE5C01        MOV     SI,015C
> 1579:010A E83400        CALL    0141
> 1579:010D 0000          ADD     [BX+SI],AL
> 1579:010F CD20          INT     20
> 
> NOTE!!!
> CALL    010F: Must point to the "clrscr" subroutine, but this subroutine
> start at 0111.
> CALL    0141: Must point to the "impstr" subroutine, but this subroutine
> start at 0143.
> 
> Note 2 bytes of displacement in the CALL instruction.
> 
> Obviously the ipl.com file compiled with .code32 does not work fine.
> 010F points directly to INT 0x20 :(     :'(
> 
> Thanks a lot for your help and time.
> 

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