Review my loader...

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bitshifter

Joined: 04 Dec 2007
Posts: 786
Location: Massachusetts, USA

bitshifter 25 Nov 2009, 19:54

You mean to set SP as 0 and let it wrap around?

Code:

xor sp,sp ; SP = 0x0000
push xxx  ; SP = 0xFFFF

25 Nov 2009, 19:54

Alphonso

Joined: 16 Jan 2007
Posts: 295

Alphonso 26 Nov 2009, 02:43

Almost like that. When pushing/popping it's done in either words, dwords or qwords.

For instance the default of 'push 1' in real mode will decrement SP by 2 (SP = 0000 - 2 = FFFE) then place word 0001 at SS:FFFE (byte FFFE=01, byte FFFF=00).

I suppose you could use FFFF as a way of checking you haven't popped more than you've pushed since if SP is set to 1 the next push should produce a double fault, never tried it though. Twisted Evil

26 Nov 2009, 02:43

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