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#include "common.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 = kinportb(0x60);

    /* If the top bit of the byte we read from the keyboard is
    *  set, that means that a key has just been released */
    if (scancode & 0x80)
    {
        /* You can use this one to see if the user released the
        *  shift, alt, or control keys... */
    }
    else
    {
        /* 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 */
        putch(kbdus[scancode]);
    }
}

/* Installs the keyboard handler into IRQ1 */
void keyboard_install()
{
    irq_install_handler(1, keyboard_handler);
}

Code: Select all

#include "common.h"

/* These are own ISRs that point to our special IRQ handler
*  instead of the regular 'fault_handler' function */
extern void irq0();
extern void irq1();
extern void irq2();
extern void irq3();
extern void irq4();
extern void irq5();
extern void irq6();
extern void irq7();
extern void irq8();
extern void irq9();
extern void irq10();
extern void irq11();
extern void irq12();
extern void irq13();
extern void irq14();
extern void irq15();

/* This array is actually an array of function pointers. We use
*  this to handle custom IRQ handlers for a given IRQ */
void *irq_routines[16] =
{
    0, 0, 0, 0, 0, 0, 0, 0,
    0, 0, 0, 0, 0, 0, 0, 0
};

/* This installs a custom IRQ handler for the given IRQ */
void irq_install_handler(int irq, void (*handler)(struct regs *r))
{
    irq_routines[irq] = handler;
    puts("Handler Installed!\n");
}

/* This clears the handler for a given IRQ */
void irq_uninstall_handler(int irq)
{
    irq_routines[irq] = 0;
}

/* Normally, IRQs 0 to 7 are mapped to entries 8 to 15. This
*  is a problem in protected mode, because IDT entry 8 is a
*  Double Fault! Without remapping, every time IRQ0 fires,
*  you get a Double Fault Exception, which is NOT actually
*  what's happening. We send commands to the Programmable
*  Interrupt Controller (PICs - also called the 8259's) in
*  order to make IRQ0 to 15 be remapped to IDT entries 32 to
*  47 */
void irq_remap(void)
{
    koutportb(0x20, 0x11);
    koutportb(0xA0, 0x11);
    koutportb(0x21, 0x20);
    koutportb(0xA1, 0x28);
    koutportb(0x21, 0x04);
    koutportb(0xA1, 0x02);
    koutportb(0x21, 0x01);
    koutportb(0xA1, 0x01);
    koutportb(0x21, 0x0);
    koutportb(0xA1, 0x0);
    putsid(2,"IRQ Installer", "IRQ remapped successfully!");
}

/* We first remap the interrupt controllers, and then we install
*  the appropriate ISRs to the correct entries in the IDT. This
*  is just like installing the exception handlers */
void irq_install()
{
    irq_remap();
    idt_set_gate(32, (unsigned)irq0, 0x08, 0x8E);
    idt_set_gate(33, (unsigned)irq1, 0x08, 0x8E);
    idt_set_gate(34, (unsigned)irq2, 0x08, 0x8E);
    idt_set_gate(35, (unsigned)irq3, 0x08, 0x8E);
    idt_set_gate(36, (unsigned)irq4, 0x08, 0x8E);
    idt_set_gate(37, (unsigned)irq5, 0x08, 0x8E);
    idt_set_gate(38, (unsigned)irq6, 0x08, 0x8E);
    idt_set_gate(39, (unsigned)irq7, 0x08, 0x8E);
    idt_set_gate(40, (unsigned)irq8, 0x08, 0x8E);
    idt_set_gate(41, (unsigned)irq9, 0x08, 0x8E);
    idt_set_gate(42, (unsigned)irq10, 0x08, 0x8E);
    idt_set_gate(43, (unsigned)irq11, 0x08, 0x8E);
    idt_set_gate(44, (unsigned)irq12, 0x08, 0x8E);
    idt_set_gate(45, (unsigned)irq13, 0x08, 0x8E);
    idt_set_gate(46, (unsigned)irq14, 0x08, 0x8E);
    idt_set_gate(47, (unsigned)irq15, 0x08, 0x8E);
    putsid(2,"IRQ Installer", "IRQ has been installed successfully!");
}

/* Each of the IRQ ISRs point to this function, rather than
*  the 'fault_handler' in 'isrs.c'. The IRQ Controllers need
*  to be told when you are done servicing them, so you need
*  to send them an "End of Interrupt" command (0x20). There
*  are two 8259 chips: The first exists at 0x20, the second
*  exists at 0xA0. If the second controller (an IRQ from 8 to
*  15) gets an interrupt, you need to acknowledge the
*  interrupt at BOTH controllers, otherwise, you only send
*  an EOI command to the first controller. If you don't send
*  an EOI, you won't raise any more IRQs */
void irq_handler(struct regs *r)
{
    /* This is a blank function pointer */
    void (*handler)(struct regs *r);

    /* Find out if we have a custom handler to run for this
    *  IRQ, and then finally, run it */
    handler = irq_routines[r->int_no - 32];
    if (handler)
    {
        handler(r);
        putsid(2,"IRQ", "IRQ handled!");
    }

    /* If the IDT entry that was invoked was greater than 40
    *  (meaning IRQ8 - 15), then we need to send an EOI to
    *  the slave controller */
    if (r->int_no >= 40)
    {
        koutportb(0xA0, 0x20);
    }

    /* In either case, we need to send an EOI to the master
    *  interrupt controller too */
    koutportb(0x20, 0x20);
}