I recently tried to add keyboard support to my kernel. Right now the driver is very similar to the one in Bran's Kernel Development tutorial (I just changed a few things). The keyboard doesn't work, there is no reaction in the kernel when a key is pressed. Still for some reason sometimes it works without me making any changes to the code (I literally don't change the code, I just recompile the kernel). Before you ask:
- Interrupts are enabled.
- The PIT and timers work fine, so I don't think something related to interrupts is the problem.
The code in my keyboard driver is the following:
Code: Select all
/* bkerndev - Bran's Kernel Development Tutorial
* By: Brandon F. ([email protected])
* Desc: Keyboard driver
*
* Notes: No warranty expressed or implied. Use at own risk. */
#include "hal.h"
/* KBDUS means US Keyboard Layout. This is a scancode table
* used to layout a standard US keyboard. I have left some
* comments in to give you an idea of what key is what, even
* though I set it's array index to 0. You can change that to
* whatever you want using a macro, if you wish! */
unsigned char kbdus[128] =
{
0, 27, '1', '2', '3', '4', '5', '6', '7', '8', /* 9 */
'9', '0', '-', '=', '\b', /* Backspace */
'\t', /* Tab */
'q', 'w', 'e', 'r', /* 19 */
't', 'y', 'u', 'i', 'o', 'p', '[', ']', '\n', /* Enter key */
0, /* 29 - Control */
'a', 's', 'd', 'f', 'g', 'h', 'j', 'k', 'l', ';', /* 39 */
'\'', '`', 0, /* Left shift */
'\\', 'z', 'x', 'c', 'v', 'b', 'n', /* 49 */
'm', ',', '.', '/', 0, /* Right shift */
'*',
0, /* Alt */
' ', /* Space bar */
0, /* Caps lock */
0, /* 59 - F1 key ... > */
0, 0, 0, 0, 0, 0, 0, 0,
0, /* < ... F10 */
0, /* 69 - Num lock*/
0, /* Scroll Lock */
0, /* Home key */
0, /* Up Arrow */
0, /* Page Up */
'-',
0, /* Left Arrow */
0,
0, /* Right Arrow */
'+',
0, /* 79 - End key*/
0, /* Down Arrow */
0, /* Page Down */
0, /* Insert Key */
0, /* Delete Key */
0, 0, 0,
0, /* F11 Key */
0, /* F12 Key */
0, /* All other keys are undefined */
};
/* Handles the keyboard interrupt */
void keyboard_handler(struct regs *r)
{
unsigned char scancode;
/* Read from the keyboard's data buffer */
scancode = inb(0x60);
/* Here, a key was just pressed. Please note that if you
* hold a key down, you will get repeated key press
* interrupts. */
/* Just to show you how this works, we simply translate
* the keyboard scancode into an ASCII value, and then
* display it to the screen. You can get creative and
* use some flags to see if a shift is pressed and use a
* different layout, or you can add another 128 entries
* to the above layout to correspond to 'shift' being
* held. If shift is held using the larger lookup table,
* you would add 128 to the scancode when you look for it */
kputc(kbdus[scancode]);
}
/* Installs the keyboard handler into IRQ1 */
void keyboard_install()
{
registerInterruptHandler(IRQ1, keyboard_handler, NF);
}
).