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Index > OS Construction > A few Realmode functions for your OS

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me239



Joined: 06 Jan 2011
Posts: 200
me239
Hello everyone, today I wanted to post a few simple, but useful, Realmode BIOS functions. The functions go as the following: printf- SI = text(NULL terminated), cmpstr(not case sensitive)- DI = buffer SI = text to compare to(caps), getinput-DI = buffer CL = number of characters to take.


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Post 19 Feb 2011, 07:03
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b1528932



Joined: 21 May 2010
Posts: 287
b1528932
pusha/popa = 80286+
Quote:
mov byte[counter], cl

I belive that byte operations are slower than native word ones. Even if i need only byte, i store word.

Quote:
mov ax, 0e0dh
int 10h
mov al, 0ah
int 10h

why you assume ah is not destroyed? Correct me if im wrong.


Quote:
mov si, msg3

you should also load segment registers, in real mode pointer is segment:offset, keep in mind.


8086 also has movs (strncpy/memcpy)/cmps (strncmp)/scas (strnlen). I dont read all you code but, so i dont know if those instructions are appropiate for it.
Post 19 Feb 2011, 10:03
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