Keyboard driver skips keystrokes
Posted: Sun Dec 11, 2016 3:19 am
I rewrote my keyboard driver yesterday. Everything works perfectly except for keystroke skipping. I don't know what it caused by. Also maybe this is because of my delay in kybd_buffer_pop() because without it system gets stuck in infinite loop. Here's my code:
Code: Select all
#include "arch/i686/kbd.h"
#include "arch/i686/regs.h"
#include "debug.h"
typedef struct {
uint8_t scancode;
char chr; //Character it corresponds to.
} kybd_scancode;
static kybd_scancode regular_scancodes[] = {
/* Numerical keys */
{0x02, '1'}, {0x03, '2'}, {0x04, '3'}, {0x05, '4'}, {0x06, '5'}, {0x07, '6'}, {0x08, '7'}, {0x09, '8'}, {0x0A, '9'}, {0x0B, '0'},
/* Some characters after numerical keys */
{0x0C, '-'}, {0x0D, '='}, /*{0x0E, '\b'},*/ {0x0F, '\t'},
/* Alphabet! */
{0x10, 'q'}, {0x11, 'w'}, {0x12, 'e'}, {0x13, 'r'}, {0x14, 't'}, {0x15, 'y'}, {0x16, 'u'}, {0x17, 'i'}, {0x18, 'o'}, {0x19, 'p'}, {0x1A, '['}, {0x1B, ']'}, {0x1C, '\n'},
{0x1E, 'a'}, {0x1F, 's'}, {0x20, 'd'}, {0x21, 'f'}, {0x22, 'g'}, {0x23, 'h'}, {0x24, 'j'}, {0x25, 'k'}, {0x26, 'l'}, {0x27, ';'}, {0x28, '\''}, {0x29, '`'},
{0x2B, '\\'}, {0x2C, 'z'}, {0x2D, 'x'}, {0x2E, 'c'}, {0x2F, 'v'}, {0x30, 'b'}, {0x31, 'n'}, {0x32, 'm'}, {0x33, ','}, {0x34, '.'}, {0x35, '/'}, {0x37, '*'},
{0x39, ' '}, {0x47, '7'}, {0x48, '8'}, {0x49, '9'}, {0x4A, '-'},
{0x4B, '4'}, {0x4C, '5'}, {0x4D, '6'}, {0x4E, '+'},
{0x4F, '1'}, {0x50, '2'}, {0x51, '3'},
{0x52, '0'}, {0x53, '.'}, {0x00, '\0'}
};
static kybd_scancode uppercase_scancodes[] = {
/* Numerical keys */
{0x02, '1'}, {0x03, '2'}, {0x04, '3'}, {0x05, '4'}, {0x06, '5'}, {0x07, '6'}, {0x08, '7'}, {0x09, '8'}, {0x0A, '9'}, {0x0B, '0'},
/* Some characters after numerical keys */
{0x0C, '-'}, {0x0D, '='}, /*{0x0E, '\b'},*/ {0x0F, '\t'},
/* Alphabet! */
{0x10, 'Q'}, {0x11, 'W'}, {0x12, 'E'}, {0x13, 'R'}, {0x14, 'T'}, {0x15, 'Y'}, {0x16, 'U'}, {0x17, 'I'}, {0x18, 'O'}, {0x19, 'P'}, {0x1A, '['}, {0x1B, ']'}, {0x1C, '\n'},
{0x1E, 'A'}, {0x1F, 'S'}, {0x20, 'D'}, {0x21, 'F'}, {0x22, 'G'}, {0x23, 'H'}, {0x24, 'J'}, {0x25, 'K'}, {0x26, 'L'}, {0x27, ';'}, {0x28, '\''}, {0x29, '`'},
{0x2B, '\\'}, {0x2C, 'Z'}, {0x2D, 'X'}, {0x2E, 'C'}, {0x2F, 'V'}, {0x30, 'B'}, {0x31, 'N'}, {0x32, 'M'}, {0x33, ','}, {0x34, '.'}, {0x35, '/'}, {0x37, '*'},
{0x39, ' '}, {0x47, '7'}, {0x48, '8'}, {0x49, '9'}, {0x4A, '-'},
{0x4B, '4'}, {0x4C, '5'}, {0x4D, '6'}, {0x4E, '+'},
{0x4F, '1'}, {0x50, '2'}, {0x51, '3'},
{0x52, '0'}, {0x53, '.'}, {0x00, '\0'}
};
static kybd_scancode shift_modified_scancodes[] = {
/* Numerical keys */
{0x02, '!'}, {0x03, '@'}, {0x04, '#'}, {0x05, '$'}, {0x06, '%'}, {0x07, '^'}, {0x08, '&'}, {0x09, '*'}, {0x0A, '('}, {0x0B, ')'},
/* Some characters after numerical keys */
{0x0C, '_'}, {0x0D, '+'}, /*{0x0E, '\b'},*/ {0x0F, '\t'},
/* Alphabet! */
{0x10, 'Q'}, {0x11, 'W'}, {0x12, 'E'}, {0x13, 'R'}, {0x14, 'T'}, {0x15, 'Y'}, {0x16, 'U'}, {0x17, 'I'}, {0x18, 'O'}, {0x19, 'P'}, {0x1A, '{'}, {0x1B, '}'}, {0x1C, '\n'},
{0x1E, 'A'}, {0x1F, 'S'}, {0x20, 'D'}, {0x21, 'F'}, {0x22, 'G'}, {0x23, 'H'}, {0x24, 'J'}, {0x25, 'K'}, {0x26, 'L'}, {0x27, ':'}, {0x28, '"'}, {0x29, '~'},
{0x2B, '\\'}, {0x2C, 'Z'}, {0x2D, 'X'}, {0x2E, 'C'}, {0x2F, 'V'}, {0x30, 'B'}, {0x31, 'N'}, {0x32, 'M'}, {0x33, '<'}, {0x34, '>'}, {0x35, '/'}, {0x37, '*'},
{0x39, ' '}, {0x47, '7'}, {0x48, '8'}, {0x49, '9'}, {0x4A, '-'},
{0x4B, '4'}, {0x4C, '5'}, {0x4D, '6'}, {0x4E, '+'},
{0x4F, '1'}, {0x50, '2'}, {0x51, '3'},
{0x52, '0'}, {0x53, '.'}, {0x00, '\0'}
};
typedef struct {
int lshift : 1;
int rshift : 1;
int lctrl : 1;
int rctrl : 1;
int numlk : 1;
int capslk : 1;
int scrllk : 1;
} kybd_modifier_key_states;
static kybd_modifier_key_states modifier_keys;
static char keyboard_buffer[256] = {};
static uint8_t kybd_buffer_current_position = 0; //0 to 255
static void kybd_buffer_push(char value)
{
if(kybd_buffer_current_position < 255)
keyboard_buffer[kybd_buffer_current_position++] = value;
else
{
printk("Keyboard buffer overflow! Keypresses will NOT be processed before buffer will be freed. User hit the keys randomly in Flash speed, system is too slow, or BPS monkeys just mistaken?");
return;
}
}
static char kybd_buffer_pop()
{
if(kybd_buffer_current_position > 0)
return keyboard_buffer[--kybd_buffer_current_position];
else
{
inb(0x60); //Note for OSDev.org users: without any kind of delay my code infinitely loops. O_O
return 0; //we have nothing in the buffer
}
}
//Interrupt part of the keyboard driver.
volatile bool kbd_irq_fired=false;
void kbd_wait_irq()
{
//if(kbd_irq_fired){while(kbd_irq_fired);return;}
while(!kbd_irq_fired);
kbd_irq_fired=false;
}
char kbd_scancode_convert(uint8_t scancode)
{
if(modifier_keys.capslk)
{
for(int i=0; uppercase_scancodes[i].scancode != 0x00; i++)
if(uppercase_scancodes[i].scancode == scancode)
return uppercase_scancodes[i].chr;
return 0;
}
else if(modifier_keys.lshift || modifier_keys.rshift)
{
for(int i=0; shift_modified_scancodes[i].scancode != 0x00; i++)
if(shift_modified_scancodes[i].scancode == scancode)
return shift_modified_scancodes[i].chr;
return 0;
}
else {
for(int i=0; regular_scancodes[i].scancode != 0x00; i++)
if(regular_scancodes[i].scancode == scancode)
return regular_scancodes[i].chr;
return 0;
}
}
void kbd_handler(struct regs *UNUSED(r))
{
kbd_irq_fired=true;
//We need to put every pressed printable key to the buffer.
uint8_t scancode = inb(KBD_DATA);
switch(scancode)
{
case KEY_LSHIFT_P: modifier_keys.lshift = 1; break;
case KEY_RSHIFT_P: modifier_keys.rshift = 1; break;
case KEY_LSHIFT_R: modifier_keys.lshift = 0; break;
case KEY_RSHIFT_R: modifier_keys.rshift = 0; break;
default: kybd_buffer_push(kbd_scancode_convert(scancode)); break;
}
}
uint8_t kbd_getchar()
{
char ret=0;
while(!ret)
{
kbd_wait_irq();
ret = kybd_buffer_pop();
}
return ret;
}
size_t kbd_gets(char *s)
{
uint8_t c=0;
int i=0;
while(true)
{
c=kbd_getchar();
if(c>0)
{
if(c=='\n')
{
s[i]='\0';
return i;
}
if(c=='\b')
{
if(i>0)
{
tty_putchar('\b');
s[--i]=0;
}
}
tty_putchar(c);
s[i++]=c;
}
}
}
void kbd_scancodes_setup()
{
//IMPORTANT: Remove that function as soon as possible, it does nothing.
}
//Keyboard-powered CPU reset.
void kbd_reset_cpu()
{
asm("cli");
uint8_t good = 0x02;
while (good & 0x02)
good = inb(0x64);
outb(0x64, 0xFE);
tty_wrstr("Keyboard CPU reset failed.");
asm("hlt");
}
