keyboard.c

#include "keyboard.h"
#include "console.h"
#include <stdbool.h>

bool shift_active = false;

static inline void outb(uint16_t port, uint8_t val) {
	asm volatile ( "outb %0, %1" : : "a" (val), "Nd" (port));
}

static inline uint8_t inb(uint16_t port)
{
    uint8_t ret;
    asm volatile ( "inb %1, %0" : "=a"(ret) : "Nd"(port) );
    return ret;
}

void init_keyboard() {
	while(inb(0x64) & 0x1) {
		inb(0x60);
	}
	
	send_command(0xF0);
	waitForResponse();
	send_command(0x02);
	waitForResponse();
	send_command(0xF4);
	waitForResponse();
}

void send_command(uint8_t command) {
	while(inb(0x64) & 0x2) {}
	outb(0x60,command);	
}

void waitForResponse() {
	while (!(inb(0x64) & 0x1)) {}	
	uint8_t response = inb(0x60);
}

char decodeScanCode(uint8_t scan_code) {
	char key_code;
	
	if(shift_active) {
		switch(scan_code) {
			case a: 
				key_code = 'A';
				break;
			case b:
				key_code = 'B';
				break;
			case c:
				key_code = 'C';
				break;
			case d: 
				key_code = 'D';
				break;
			case e:
				key_code = 'E';
				break;
			case f:
				key_code = 'F';
				break;
			case g: 
				key_code = 'G';
				break;
			case h:
				key_code = 'H';
				break;
			case i:
				key_code = 'I';
				break;
			case j: 
				key_code = 'J';
				break;
			case k:
				key_code = 'K';
				break;
			case l:
				key_code = 'L';
				break;
			case m: 
				key_code = 'M';
				break;
			case n:
				key_code = 'N';
				break;
			case o:
				key_code = 'O';
				break;
			case p: 
				key_code = 'P';
				break;
			case q:
				key_code = 'Q';
				break;
			case r:
				key_code = 'R';
				break;
			case s: 
				key_code = 'S';
				break;
			case t:
				key_code = 'T';
				break;
			case u:
				key_code = 'U';
				break;
			case v: 
				key_code = 'V';
				break;
			case w:
				key_code = 'W';
				break;
			case x:
				key_code = 'X';
				break;
			case y: 
				key_code = 'Y';
				break;
			case z:
				key_code = 'Z';
				break;
			case space:
				key_code = ' ';
				break;
			case enter:
				key_code = '\n';
				break;
			default: 
				return 0;
		}
	} else {
		switch(scan_code) {
			case a: 
				key_code = 'a';
				break;
			case b:
				key_code = 'b';
				break;
			case c:
				key_code = 'c';
				break;
			case d: 
				key_code = 'd';
				break;
			case e:
				key_code = 'e';
				break;
			case f:
				key_code = 'f';
				break;
			case g: 
				key_code = 'g';
				break;
			case h:
				key_code = 'h';
				break;
			case i:
				key_code = 'i';
				break;
			case j: 
				key_code = 'j';
				break;
			case k:
				key_code = 'k';
				break;
			case l:
				key_code = 'l';
				break;
			case m: 
				key_code = 'm';
				break;
			case n:
				key_code = 'n';
				break;
			case o:
				key_code = 'o';
				break;
			case p: 
				key_code = 'p';
				break;
			case q:
				key_code = 'q';
				break;
			case r:
				key_code = 'r';
				break;
			case s: 
				key_code = 's';
				break;
			case t:
				key_code = 't';
				break;
			case u:
				key_code = 'u';
				break;
			case v: 
				key_code = 'v';
				break;
			case w:
				key_code = 'w';
				break;
			case x:
				key_code = 'x';
				break;
			case y: 
				key_code = 'y';
				break;
			case z:
				key_code = 'z';
				break;
			case space:
				key_code = ' ';
				break;
			case enter:
				key_code = '\n';
				break;
			default: 
				return 0;
		}
	}
	
	return key_code;
}

void keyboard_handler() {
	uint8_t scan_code;
	if(inb(0x64) & 0x1) {
		scan_code = inb(0x60);
	}
	
	//handle key up key down
	if(scan_code & (1 << 7)) {
		//shift key released
		if(scan_code == 0xaa || scan_code == 0xb6) { //shift key released
			shift_active = !shift_active;
		}
	} else {
		//key pressed
		
		
		if(scan_code == 0x2a || scan_code == 0x36) { //shift key pressed
			shift_active = !shift_active;
		} else if(scan_code == 0x3a) { //capslock toogle
			shift_active = !shift_active;
		} else if(scan_code == 0x0e) { // Backspace pressed
			kdelc();
		} else {
			char key = decodeScanCode(scan_code);
			kputc(key);
		} 
	}
	
}