Re: Searching for string problems

[Andrew Kirilenko <icedank@gmx.net>]

Hello!

> If you need to search the whole BIOS for that string, you need to
> set up an outer loop using an unused register which starts at
> the offset of the BIOS and increments by one byte everytime
> you can't find the string. This value gets put into %di, instead
> of the absolute number specified above.
>
> Like:
>
> scan:	movw	%cs, %ax
> 	movw	%ax, %ds
> 	movw	%ax, %es
> 	movw	$where_in_BIOS_to_start, %bx
> 	cld
> 1:	movw	$cl_id_str, %si		# Offset of search string
> 	movw	$cl_id_end, %cx		# Offset of string end + 1
> 	subw	%si, %cx		# String length
> 	decw	%cx			# Don't look for the \0
> 	movw	%bx, %di		# ES:DI = where to look
> 	repz	cmpsb			# Loop while the same
> 	jz	found			# Found the string
> 	incb	%bx			# Next starting offset
> 	cmpb	$_BIOS_END, %bx		# Check for limit
> 	jb	1b			# Continue
> never_found_anywhere:
>
> found:

I've written something similar to this before - and it wont' work, so I've 
reimplemented it. The problem is, that I don't know how to set ES properly. I 
only know, that BIOS data (and code) is located in 0xe000..0xf000 (real 
address).

Best regards,
Andrew.