Messages in this thread | | | Date | Wed, 23 Apr 2003 12:11:23 -0700 | From | "Randy.Dunlap" <> | Subject | Re: Searching for string problems |
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On Wed, 23 Apr 2003 22:00:20 +0300 Andrew Kirilenko <icedank@gmx.net> wrote:
| Hello! | | > > > > 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). | > > > | > > > Yeah. So. I set ES and DS to be exactly where CS is. This means that | > > > if your &!)(^$&_ code executes it will work. So, instead of trying | > > > it, you just blindly ignore it and state that it won't work. | > > > | > > > Bullshit. I do this for a living and I gave you some valuable time | > > > which you rejected out-of-hand. Have fun. | > > | > > Of course, I've tried your code as well - the same result! Sorry, if you | > > haven't understand me. | > > | > > The problem is, that I don't know where this BIOS code is relative to | > > current code segment (CS). I only know (hope), that it should be in | > > 0x0:0xe000...0x0:0xf000. I have tried to set ES to 0 (xor %ax, %ax; mov | > > %ax, %es) - no luck as well. BTW, `strings /dev/mem | grep "REQUESTED | > > STRING"` founds it perfectly... | > > | > > Best regards, | > > Andrew. | > > - | > | > The bios is in segment 0xf000. You set ES to that area. ES:DI will | > start at 0 if bx=0 in the code shown. The BIOS is only 64k. | > This means that where bx is being incremented (it should be incw, not | > incb). It would generate an assembly error with incb which is why | > I knew you didn't even try it. -- you just jnz back to 1b, without | > any additional test. | | 1. How to set ES to this area? "movw $0xf000, %ax ; movw %ax, %es" will be | enough?
That should do it.
| 2. Is the are really starts from 0xf000? Or 0xe000?
Most current ones that I know of are 128 KB, so start at segment 0xe000:0 thru 0xf000:ffff. Just boot DOS, run debug, and display those areas. That will answer it for you. :)
| 3. I'm smart enough to correct "incb %bx" to "incw %bx" ;)
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