Re: [Nasm-users] calling 'C' functions

[zak100 <zul...@ya...>]

Its working now. Thanks for your time, commands, description and for your
effort.

Zulfi.


Frank Kotler-3 wrote:
> 
> zak100 wrote:
>> Hi,
>> Thanks for your help. 
>>  
>> 
>> I have received your mz folder. It has two binaries: boot and image.
>> 'boot'
>> is fine
>> but when i tried to load image to sector 2 it didnt work. Maybe I am
>> doing
>> something 
>> wrong.
> 
> What *I* do is to combine "boot.bin" plus "mzt1.exe"(!) into 
> "image.bin", and load the whole thing, starting at sector 1. You could 
> use "image.bin", loading it to sector 1 - "writeit" won't do (only does 
> 512 bytes), but "partcopy" ought to - "partcopy image.bin 0 323 -f0", I 
> think would do it. (I create "image.bin" with "cat", but you could use 
> "copy /b boot.bin+mzt1.exe image bin", I think)
> 
> Alternatively, you could write them separately - "boot.bin" with 
> "writeit" or "partcopy", and "partcopy" for "mzt1.exe". The idea is 
> simply to eliminate the "exe2bin" step, and load an MZ executable.
> 
>> However, I didnt find any 'C' files.
> 
> Heh! No, I'm not taking the course, so I don't have to follow the rules.
> :)
> 
> I don't "do" C, unless absolutely necessary - haven't got a 16-bit 
> compiler, in any case. If you look at "kmain.asm", "write.asm" and 
> "getkey.asm", you'll see that they're "fake C" - you "should" be able to 
> replace them with "real C" equivalents... if I've done it right (big 
> if). "mzt1.asm" serves the purpose (approximately) of "crt0" or whatever 
> your compiler calls the "startup code" that calls "main" - "kmain", in 
> this case.
> 
> I've modified your bootsector (the one we "translated" from Tasmese) - 
> among other things, I altered it to read just one sector (reading 5 
> tracks wasn't working for me, for some reason). My "mzt1.exe" is well 
> under that, so far, but when it gets more extensive, the bootsector is 
> going to have to change. I mention this because, in my experience, C 
> tends to produce "bloated" code, compared to asm, and if you go over 512 
> bytes, it's going to mysteriously quit working.
> 
> Another way I haven't "followed the assignment" is that I used int 10h 
> for "write()". I'm confident I can write a string to B800:????, if I can 
> find the string! The purpose of this step of the exercise, for me, is to 
> be able to find my data! I figure if I can find the string, I can find 
> "cursor_x" and "cursor_y", and I know how to find the "screen". This 
> seems to "work"... as long as I put code and data in the same segment. 
> So far, my attempts to declare a "proper stack" and put "data" in 
> "segment data" have failed. What I'm seeing in the executable header 
> doesn't match what I "expect" to see. If and when I figure out how to 
> deal with that, and with far calls and far data, I won't be stuck in a 
> single 64k segment! (plus, it's not nice to teach beginners to ignore 
> the warning about "no stack"! :)
> 
> I don't know what compiler you're using, or what you're telling it. Are 
> you sticking to "model tiny"? I'm not sure what a compiler (and Alink) 
> will emit, from the code you posted. If you want to send me some 
> "output" - either before or after "exe2bin", or both, I'll try to figure 
> out how we might load it (if you're still having trouble with that). No 
> guarantee - I can't always figure out how to load my own stuff. :) "Post 
> exe2bin" should be "easier"... maybe...
> 
> Sorry I wasn't clearer about how to use that example. I was pretty tired 
> when I posted. ("try this *one* more thing and test it and then I'm 
> going to bed!"...) I should have mentioned that while "build" won't work 
> in dos (a bash script), it has some clues to how to put the thing
> together.
> 
> Lemme see if I remember how to write a dos batch file...
> 
> call nasm -f bin bootmz.asm -o boot.bin
> 
> call nasm -f obj mzt1.asm
> call nasm -f obj kmain.asm
> call nasm -f obj write.asm
> call nasm -f obj getkey.asm
> 
> call alink -oEXE mzt1.obj kmain.obj write.obj getkey.obj
> 
> call copy /b boot.bin+mzt1.exe image.bin
> call partcopy image.bin 0 323 -f0
> echo done
> 
> That's totally untested (and doesn't check returned errorlevels). Good
> luck!
> 
> Best,
> Frank
> 
> 
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