printf

[frank]

the basic functions work now (putc,gotoxy)
but printf does not work...

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 printf("fffff");        <- that's how I call the printf function

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void printf(char * string)
{
 unsigned short *vidmem = (short*) 0xb8000;
  int i=0;
  if (string[0]=='f'){
   vidmem[i] = 0x1F66; 
  } 
}

it does print an f without the if statement, but does not with it.
So the first character is not f....
where did those characters go?

[crazybuddha]

You are probably expecting that the string is passed on the stack. It isn't.

We need to know more about your linking to give a more complete answer.

[frank]

> You are probably expecting that the string is passed on the stack. It isn't.
I understand, so how is it passed?


This is the compile line:

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gcc -O4 -c kern.c
ld -o kern -Ttext 0x0 -e 0x0 kern.o
objcopy -R .note -R .comment -S -O binary kern kern.bin

(I jump to the main in the kernel using asm("jmp main"); on 0x0 of the kernel)

this is how I've set up the stack:

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mov ax,0x10
mov ss,ax
mov esp,0xFFFF

[frank]

Got it working now ;D

the Ttext was wrong, since i've loaded it into 0x1000 it can't be 0x0

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gcc -O4 -c kern.c
ld -o kern -Ttext 0x1000 -e 0x0 kern.o
objcopy -R .note -R .comment -S -O binary kern kern.bin