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timer(IRQ 0)
Posted: Thu Jan 02, 2003 10:30 am
by hanoi
Hey!
I have some problems with the timer..
I've looked in a few sources, but they did exactly like me.
My IDT&PIC-Remap are working(i know from keyboard).
So i am wondering why it doesn't work...
-Code-
void timer_set(unsigned int frequency)
{
unsigned short foo = 1193182 / frequency;
outp(0x43, 0x36);
outp(0x40, (unsigned char) foo);
outp(0x40, (unsigned char)(foo >>
);
return;
}
void main()
{
...
timer_set( 100 ); //set frequency of timer 0(which is connected to IRQ 0) to 100
setVector(0x20, (void *)(tim));
...
}
asm (
".globl _tim \n"
"_tim: \n"
"cli \n"
"pusha \n"
"pushf \n"
"call _timer \n"
"popf \n"
"popa \n"
"sti \n"
"iret \n"
);
void timer()
{
outp(0x20,0x20);
k_printf("timer\n");
counter++;
return;
}
-Code-
I would be glad toget it working, because without it'd be difficult to make a multi-tasking somehow.
Re:timer(IRQ 0)
Posted: Thu Jan 02, 2003 10:59 am
by jrfritz
You need a ASM stub and here:
in asm:
GLOBAL IRQ0
EXTERN PIT
IRQ0:
pusha
call PIT
mov al, 0x20
out 0x20, al
popa
IRET
in your C code:
extern void IRQ0(); // Your IDT calles THIS function
void PIT()
{
k_printf( "timer " );
counter++;
}
Re:timer(IRQ 0)
Posted: Thu Jan 02, 2003 11:03 am
by hanoi
asm (
".globl _tim \n"
"_tim: \n"
"cli \n"
"pusha \n"
"pushf \n"
"call _timer \n"
"popf \n"
"popa \n"
"sti \n"
"iret \n"
);
setVector(0x20, (void *)(tim));
Re:timer(IRQ 0)
Posted: Thu Jan 02, 2003 11:04 am
by hanoi
this should work as the other
Re:timer(IRQ 0)
Posted: Thu Jan 02, 2003 11:08 am
by jrfritz
Opps didn't read that.
Must be your timer_set.
Try without it.
Re:timer(IRQ 0)
Posted: Thu Jan 02, 2003 11:11 am
by hanoi
unfourtanetly not.
I dunno what to do
Re:timer(IRQ 0)
Posted: Thu Jan 02, 2003 11:12 am
by richie
It would be possible that you forgot to enable IRQ 0 at the PIC. This would explain why you get no timer-int but you get a keyboard-int.
If your timer-interrupt-routine is never called it has something to do with enabling the interrupts: The interrupt-flag must be set (sti), your IDT must be set right and the PIC must be set right. If your keyboard-interrupt-handler works the only possible fault can be the PIC.
If I understand your right you copied the code from some other OS-Source. To understand how the PIc is programmed you can go to the following page where you find some useful links to PIC-related topics:
http://www.nondot.org/sabre/os/articles/MiscellaneousDevices/
Re:timer(IRQ 0)
Posted: Thu Jan 02, 2003 11:14 am
by jrfritz
Maybe your RemapIRQs doesn't remap IRQ0 ???
Re:timer(IRQ 0)
Posted: Thu Jan 02, 2003 11:16 am
by hanoi
i've put outp(0x20,0); outp(0xA0, 0);
at the end of the PIC_remap function....
Re:timer(IRQ 0)
Posted: Thu Jan 02, 2003 11:30 am
by hanoi
this enables all IRQs , doesn't it?
Re:timer(IRQ 0)
Posted: Thu Jan 02, 2003 11:42 am
by jrfritz
Maybe your out of memory...where did you load your OS into?
When you run out of memory...your IDT won't work properly.
Re:timer(IRQ 0)
Posted: Thu Jan 02, 2003 11:46 am
by hanoi
My OS is loaded from my bootloader to 0x100000
Re:timer(IRQ 0)
Posted: Thu Jan 02, 2003 11:49 am
by richie
I have the following function to remap all IRQs to ints and enable them:
Code: Select all
//The following code is not my idea,
//it is the mixture of different OS-sources
#define PIC1_COMMAND 0x20
#define PIC1_DATA 0x21
#define PIC2_COMMAND 0xA0
#define PIC2_DATA 0xA1
#define ICW1_ICW4 0x01
#define ICW1_INIT 0x10
#define ICW4_8086 0x01
void remap_pics(int pic1, int pic2)
{
unsigned char a1, a2;
a1=inportb(PIC1_DATA);
a2=inportb(PIC2_DATA);
outportb(PIC1_COMMAND, ICW1_INIT+ICW1_ICW4);
outportb(PIC2_COMMAND, ICW1_INIT+ICW1_ICW4);
outportb(PIC1_DATA, pic1);
outportb(PIC2_DATA, pic2);
outportb(PIC1_DATA, 4);
outportb(PIC2_DATA, 2);
outportb(PIC1_DATA, ICW4_8086);
outportb(PIC2_DATA, ICW4_8086);
outportb(PIC1_DATA, a1);
outportb(PIC2_DATA, a2);
};
To remap:
IRQ 0 - IRQ 7 => INT 0x20 - INT 0x27
IRQ 8 - IRQ 15 => INT 0x28 - INT 0x2F
You can use the following code:
Code: Select all
//in your init_kernel_function
//...
remap_pics(0x20, 0x28); // irq 0 20h irq 8 28h
sti(); //enable interrupts
//...
Of course you need a handler for every int from 0x20 to 0x2F even if these handlers are only dummy handlers.
Re:timer(IRQ 0)
Posted: Thu Jan 02, 2003 11:49 am
by jrfritz
May I see your bootloader code? I can't get mine to load at 1 meg.
You can post it in the Text Truncated thread...
as for your PIT...I can't see the problem...
Re:timer(IRQ 0)
Posted: Thu Jan 02, 2003 12:13 pm
by hanoi
I can explain how i did this:
i loaded the kernel to 0x10000 with bios.
then i switched to pmode.
(i've made two big segments(4Gb)(1 data, 1 code)
Then i've copied the kernel from 0x10000 to 0x100000
with movsb:
mov ecx, Kernelsize
mov esi, 0x10000
mov edi, 0x100000
rep movsb
that's it