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

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I have also created a stack but its not detected by the linker.

Loading file test_kernel2.obj
Loading file main1.o
matched Externs
matched ComDefs
Warning - no stack

D:\nasm prog>

CLI     ;Clear Interupt Flag so while setting 
        ;up the stack any interrupt would not be fired.

        mov AX,7B0h    ;lets have the stack start at 7c00h-256 = 7B00h
        mov SS,ax      ;SS:SP = 7B0h:256 = 7B00h:256
        mov SP,256     ;Lets make the stack 256 bytes.

;        Mov ax,CS      ;Set the data segment = CS = 0 
; suggest you use 0 here!

        XOR AX,AX      ;Makes AX=0.
        MOV ES,AX      ;Make ES=0
        mov DS,ax

    STI     ;Set Back the Interupt Flag after 
        ;we finished setting a stack frame.

zak100 wrote:
> 
> Hi,
> 
> The changes for jump code lies here:
> 
> GiveControlToOS: ; PROC
> 
>         LEA AX,[szDone]
>         Call PrintMessage
>         CALL GetKey
>         
> ;        db 0e9h        ;Far JMP op code.
> ;        dw 512         ;JMP 512 bytes ahead
>     ;jmp 0:7E00h;-----------------------------------At this point we are
> going to Kernel code; for including C prog:test_kernel2.asm
> 
>         ;jmp 7D0h:100h
>          jmp 0:7D00h
> ;       POP AX         ;//Another why to make 
>                        ;the CPU jump to a new place.
> ;       POP AX
> ;       Push 7E0h      ;Push New CS address.
> ;       Push 0          ;Push New IP address.
>                ;The address that comes out is 7E00:0000. 
> ; comment does not match code!
> 
> 
>                ;(512 bytes Higher from were BIOS Put us.)
>        retf
> ; you'd want "retf" here.
>         
> ;GiveControlToOS EndP 
> 
> The changes for ..start lie here
> 
> ..start:
> extern _K_main
> ;--- test kernel.bin---
> 
> ;    push cs
> ;    push cs
> ;    pop ds
> ;    pop es
>     mov ax, 7E0H
>     mov ds,ax
>     mov es,ax
>     mov si, msg
> 
>     mov ah, 0Eh
>     mov bx, 7
> top:
>     lodsb
>     cmp al, 0
>     jz blackhole
>     int 10h
>     jmp short top
> 
> blackhole:
>     
>     mov cx,1000
>     Delay: Loop Delay
>     call _K_main; this is in main.c
>     hlt
>     jmp blackhole
> 
> msg db 'Welcome to the Kernel!', 0
> 
> times 0x200-($-$$) db 0
> 
> Kindly help me with this.
> 
> 
> Zulfi.
>         
> Frank Kotler-3 wrote:
>> 
>> zak100 wrote:
>>> Hi,
>>> I am able to make the binary using alink. partcopy was giving prob but
>>> it
>>> was handled as done previously.
>>> 
>>> The steps are provided below:
>>> D:\nasm prog>nasm -f bin -o boot.bin BLKernelT.asm
>>> 
>>> D:\NASMPR~1>nasm -f bin -o writeit.com writeit.asm
>>> 
>>> D:\NASMPR~1>writeit
>>> 
>>> D:\NASMPR~1>del test_kernel2.onj
>>> Could Not Find D:\NASMPR~1\test_kernel2.onj
>>> 
>>> D:\NASMPR~1>del test_kernel2.obj
>>> 
>>> D:\NASMPR~1>nasm -f obj test_kernel2.asm
>>> 
>>> D:\NASMPR~1>dir t*.obj
>>>  Volume in drive D is New Volume
>>>  Volume Serial Number is 70FD-1D2C
>>> 
>>>  Directory of D:\NASMPR~1
>>> 
>>> 07/10/2009  10:55 AM               642 test_kernel2.obj
>>>                1 File(s)            642 bytes
>>>                0 Dir(s)  22,656,360,448 bytes free
>>> 
>>> D:\NASMPR~1>alink -o kernel.bin test_kernel2.obj main1.o
>>> ALINK v1.6 (C) Copyright 1998-9 Anthony A.J. Williams.
>>> All Rights Reserved
>>> 
>>> Loading file test_kernel2.obj
>>> Loading file main1.o
>>> matched Externs
>>> matched ComDefs
>>> Warning, no entry point specified
>> 
>> You can fix this by adding a "..start:" label where you want your 
>> entrypoint.
>> 
>>> Warning - no stack
>> 
>> segment stack stack
>> resb ???? ; how big do you want? C uses a lot of stack, I understand.
>> 
>> The first "stack" is just a name - could be anything. The second "stack" 
>> is necessary to let Nasm know what we want. I've been ignoring the 
>> warning, and "let the OS take care of the stack". We set up a stack in 
>> the bootsector which should be "okay for now". When you get to task 
>> switching/multitasking, you'll want to swap stacks for each process (I 
>> imagine).
>> 
>>> D:\NASMPR~1>alink -o kernel.exe test_kernel2.obj main1.o
>>> ALINK v1.6 (C) Copyright 1998-9 Anthony A.J. Williams.
>>> All Rights Reserved
>>> 
>>> Loading file test_kernel2.obj
>>> Loading file main1.o
>>> matched Externs
>>> matched ComDefs
>>> Warning, no entry point specified
>>> Warning - no stack
>>> 
>>> D:\NASMPR~1>del kernel.bin
>>> 
>>> D:\NASMPR~1>exe2bin kernel.exe kernel.bin
>> 
>> Good. This produces a .com file (no matter what we call it) which 
>> expects to be loaded at 100h into... whatever segment.
>> 
>>> D:\NASMPR~1>partcopy kernel.bin 0 200 -f0 200
>>> Failed to read source at offset 144
>>> D:\NASMPR~1>partcopy kernel.bin 0 144 -f0 200
>>> 
>>> D:\NASMPR~1>
>>> -----------------------------------
>>> 
>>> But when I rebooted , I got boot sector statment but I am not seeing the
>>> "welcome....." kernel message.
>>> Can somebody plz guide me??
>> 
>> Try jumping to 7D0h:100h (assuming that you're writing this to 7E00h).
>> 
>> I haven't done anything further with this. I've downloaded source (in 
>> assembly) for an exe2bin clone, thinking we might be able to modify it 
>> to produce a binary at "org 0", or perhaps create a loader for MZ to be 
>> included in our code. Only just begun to look at it.
>> 
>> Tyler mentioned using bochs for testing. That would speed up development 
>> a *lot* (especially for me, since I don't like rebooting). I've 
>> downloaded bochs a couple of times, but never tried it. I've seen too 
>> many posts about "my bootsector works in bochs, but not in a real 
>> machine" (or vise versa), and "bochs is giving me this error message, 
>> what the heck does it mean?"... suggesting that bochs doesn't accurately 
>> reflect "real hardware" (can't match *all* of 'em, of course), and has a 
>> "learning curve" to it...
>> 
>> Any tips, Tyler? Is bochs going to insist on seeing a full 1.44M image 
>> before it'll boot from a "fake floppy"? Well, I'll figure it out (or 
>> not), if and when I get around to trying it...
>> 
>> Best,
>> Frank
>> 
>> 
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>> 
> 
> 

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