Going to call it a day for today, I don't think it is as simple as I

thought... a shell I think will require processes, and can't be faked no
matter what I want to do. I'll need to communicate between the driver
and caller as well, and all of this will need to be done on the current
stack as is. Meaning, I can't just "poll for input" because there is no
other place BUT a variable on the stack to poll on. I was going to have
the driver invoke a callback with the input received... but this is
needlessly complicated. As well, this handler invoking handler after
handler means that I will have interrupts disabled the ENTIRE time that
the higher-level callback is invoked for, which also means that if it
relies on another service that requires interrupts to run, it will just
block indefinitely.

So pretty much I will be implementing memory management next, most
likely, and go from there.

Author: Louis Jenkins

src/kernel/drivers/kbd.c

@@ -1,11 +1,120 @@
 #include <include/kbd.h>
 #include <include/vga.h>
-#include <stdbool.h>
 #include <include/idt.h>
 #include <include/io_port.h>
+#include <include/helpers.h>
+#include <stdbool.h>
+#include <stdio.h>
+
+// Below are the two scan tables for normal scan codes, used to provide a mapping from scan code to character code. 
+// A scan table entry of [0x01] = KBD_KEY_ESC would have a scan code of 0x01, and a character code of KBD_KEY_ESC.
+static const uint8_t KBD_SCAN_TABLE[KBD_NSCANS] = {
+    [0x01] = KBD_KEY_ESC, 
+    [0x02] = KBD_KEY_1, 
+    [0x03] = KBD_KEY_2,
+    [0x04] = KBD_KEY_3,
+    [0x05] = KBD_KEY_4,
+    [0x06] = KBD_KEY_5,
+    [0x07] = KBD_KEY_6,
+    [0x08] = KBD_KEY_7,
+    [0x09] = KBD_KEY_8,
+    [0x0A] = KBD_KEY_9,
+    [0x0B] = KBD_KEY_0,
+    [0x0C] = KBD_KEY_MINUS,
+    [0x0D] = KBD_KEY_EQUALS,
+    [0x0E] = KBD_KEY_BACKSPACE,
+    [0x0F] = KBD_KEY_TAB,
+    [0x10] = KBD_KEY_Q,
+    [0x11] = KBD_KEY_W,
+    [0x12] = KBD_KEY_E,
+    [0x13] = KBD_KEY_R,
+    [0x14] = KBD_KEY_T,
+    [0x15] = KBD_KEY_Y,
+    [0x16] = KBD_KEY_U,
+    [0x17] = KBD_KEY_I,
+    [0x18] = KBD_KEY_O,
+    [0x19] = KBD_KEY_P,
+    [0x1A] = KBD_KEY_LBRACKET,
+    [0x1B] = KBD_KEY_RBRACKET,
+    [0x1C] = KBD_KEY_ENTER,
+    [0x1D] = KBD_KEY_LCTRL,
+    [0x1E] = KBD_KEY_A,
+    [0x1F] = KBD_KEY_S,
+    [0x20] = KBD_KEY_D,
+    [0x21] = KBD_KEY_F,
+    [0x22] = KBD_KEY_G,
+    [0x23] = KBD_KEY_H,
+    [0x24] = KBD_KEY_J,
+    [0x25] = KBD_KEY_K,
+    [0x26] = KBD_KEY_L,
+    [0x27] = KBD_KEY_SEMICOLON,
+    [0x28] = KBD_KEY_APOSTROPH,
+    [0x29] = KBD_KEY_GRAVE_ACCENT,
+    [0x2A] = KBD_KEY_LSHIFT,
+    [0x2B] = KBD_KEY_BACK_SLASH,
+    [0x2C] = KBD_KEY_Z,
+    [0x2D] = KBD_KEY_X,
+    [0x2E] = KBD_KEY_C,
+    [0x2F] = KBD_KEY_V,
+    [0x30] = KBD_KEY_B,
+    [0x31] = KBD_KEY_N,
+    [0x32] = KBD_KEY_M,
+    [0x33] = KBD_KEY_COMMA,
+    [0x34] = KBD_KEY_PERIOD,
+    [0x35] = KBD_KEY_SLASH,
+    [0x36] = KBD_KEY_RSHIFT,
+    [0x37] = KBD_KP_KEY_ASTERISK,
+    [0x38] = KBD_KEY_LALT,
+    [0x39] = KBD_KEY_SPACE,
+    [0x3A] = KBD_KEY_CAPS_LOCK,
+    [0x3B] = KBD_KEY_F1,
+    [0x3C] = KBD_KEY_F2,
+    [0x3D] = KBD_KEY_F3,
+    [0x3E] = KBD_KEY_F4,
+    [0x3F] = KBD_KEY_F5,
+    [0x40] = KBD_KEY_F6,
+    [0x41] = KBD_KEY_F7,
+    [0x42] = KBD_KEY_F8,
+    [0x43] = KBD_KEY_F9,
+    [0x44] = KBD_KEY_F10,
+    [0x45] = KBD_KEY_NUMLOCK,
+    [0x46] = KBD_KEY_SCROLL_LOCK,
+    [0x47] = KBD_KP_KEY_7,
+    [0x48] = KBD_KP_KEY_8,
+    [0x49] = KBD_KP_KEY_9,
+    [0x4A] = KBD_KP_KEY_MINUS,
+    [0x4B] = KBD_KP_KEY_4,
+    [0x4C] = KBD_KP_KEY_5,
+    [0x4D] = KBD_KP_KEY_6,
+    [0x4E] = KBD_KP_KEY_PLUS,
+    [0x4F] = KBD_KP_KEY_1,
+    [0x50] = KBD_KP_KEY_2,
+    [0x51] = KBD_KP_KEY_3,
+    [0x52] = KBD_KP_KEY_0,
+    [0x53] = KBD_KP_KEY_PERIOD,
+    [0x57] = KBD_KEY_F11,
+    [0x58] = KBD_KEY_F12
+};
+
+// Escaped scan code sequences are multibyte, and begin with '0xE0'.
+static const uint8_t KBD_ESCAPED_SCAN_TABLE[KBD_NSCANS] = {
+    [0x1C] = KBD_KP_KEY_ENTER,
+    [0x1D] = KBD_KEY_RCTRL,
+    [0x35] = KBD_KP_KEY_SLASH,
+    [0x38] = KBD_KEY_RALT,
+    [0x48] = KBD_KEY_UP,
+    [0x49] = KBD_KEY_PAGE_UP,
+    [0x4B] = KBD_KEY_LEFT,
+    [0x4D] = KBD_KEY_RIGHT,
+    [0x4F] = KBD_KEY_PAGE_DOWN,
+    [0x50] = KBD_KEY_DOWN,
+    [0x51] = KBD_KEY_PAGE_DOWN,
+    [0x52] = KBD_KEY_INSERT,
+    [0x53] = KBD_KEY_DELETE
+};
 
-static uint8_t (*scan_to_char(uint8_t));
 
+// Converts a character code to string
 static const char *to_string(uint8_t code) {
 	const char *str;
 	switch (code) {
@@ -287,6 +396,7 @@ static const char *to_string(uint8_t code) {
 	return str;
 }
 
+// Converts escaped character codes to string
 static const char *escaped_to_string(uint8_t code) {
 	const char *str;
 	switch (code) {
@@ -331,9 +441,14 @@ static const char *escaped_to_string(uint8_t code) {
 	return str;
 }
 
+// Keyboard state, which drives the statement machine in handler
 static uint8_t state = 0;
 
-static void keyboard_irq_handler(struct registers *regs) {
+// A simple (and temporary) handler that reads input from the hardware (keyboard)
+// and converts it into it's respective character codes.
+// Temporary: It currently prints out the key being pressed but that is because
+// I hav enot implemented a more adequate way of doing this.
+static void keyboard_irq_handler(struct registers *UNUSED(regs)) {
 	// Get what key has been pressed
 	uint8_t scancode = inb(KBD_PORT);
 
@@ -343,26 +458,29 @@ static void keyboard_irq_handler(struct registers *regs) {
 		return;
 	}
 
+	// All scan codes signify that a key has been released by setting the most significant bit
 	bool released = scancode & 0x80;
 	scancode &= ~0x80;
 
+	// On each key press, we write prettily to the same line.
 	vga_clear();
 	vga_set_x(0);
 	printf("Scancode: %x, You %s: ", scancode, released ? "Released" : "Pressed");
 
+	// State-Based machine, which determines which scan table to decode from.
 	switch (state) {
 		// Waiting for first byte
 		case 0:
 			printf("%s", to_string(KBD_SCAN_TABLE[scancode]));
 			return;
-		// Wait
-			ing for second byte of multibyte sequence
+		// Waiting for second byte of multibyte sequence
 		case 1:
 			printf("%s", escaped_to_string(KBD_ESCAPED_SCAN_TABLE[scancode]));
 			state = 0;
 	}
 }
 
+// Simple initializer that registers IRQ handler
 void keyboard_init() {
 	register_interrupt_handler(IRQ1, keyboard_irq_handler);
 }

src/kernel/drivers/rtc.c

@@ -13,7 +13,7 @@ static uint8_t as_binary(uint8_t bcd) {
 }
 
 void rtc_init() {
-	// TODO
+	// TODO: Register IRQ handler (IRQ8)
 }
 
 uint8_t rtc_get_second() {

src/kernel/include/helpers.h

@@ -2,5 +2,6 @@
 #define MOLTAROS_HELPERS_H
 
 #define CEILING(x,y) (((x) + (y) - 1) / (y))
+#define UNUSED(x) (__attribute__((__unused__)) x)
 
 #endif /* end MLTAROS_HELPERS_H */

src/kernel/include/kbd.h

@@ -8,9 +8,12 @@
 #define KBD_NSCANS 0x80
 #define KBD_ESCAPED_NSCANS 0xE0
 
+
 /*
-    Character Codes: The layout is based on my work laptop's keyboard layout.
+    A minimal keyboard driver that conforms to my laptop's keyboard layout.
 */
+
+// Below is all character codes for the given buttons.
 enum {
     KBD_KEY_ESC = 0x1, 
     KBD_KEY_F1, 
@@ -116,110 +119,6 @@ enum {
     KBD_KP_KEY_PERIOD
 };
 
-static const uint8_t KBD_SCAN_TABLE[KBD_NSCANS] = {
-    [0x01] = KBD_KEY_ESC, 
-    [0x02] = KBD_KEY_1, 
-    [0x03] = KBD_KEY_2,
-    [0x04] = KBD_KEY_3,
-    [0x05] = KBD_KEY_4,
-    [0x06] = KBD_KEY_5,
-    [0x07] = KBD_KEY_6,
-    [0x08] = KBD_KEY_7,
-    [0x09] = KBD_KEY_8,
-    [0x0A] = KBD_KEY_9,
-    [0x0B] = KBD_KEY_0,
-    [0x0C] = KBD_KEY_MINUS,
-    [0x0D] = KBD_KEY_EQUALS,
-    [0x0E] = KBD_KEY_BACKSPACE,
-    [0x0F] = KBD_KEY_TAB,
-    [0x10] = KBD_KEY_Q,
-    [0x11] = KBD_KEY_W,
-    [0x12] = KBD_KEY_E,
-    [0x13] = KBD_KEY_R,
-    [0x14] = KBD_KEY_T,
-    [0x15] = KBD_KEY_Y,
-    [0x16] = KBD_KEY_U,
-    [0x17] = KBD_KEY_I,
-    [0x18] = KBD_KEY_O,
-    [0x19] = KBD_KEY_P,
-    [0x1A] = KBD_KEY_LBRACKET,
-    [0x1B] = KBD_KEY_RBRACKET,
-    [0x1C] = KBD_KEY_ENTER,
-    [0x1D] = KBD_KEY_LCTRL,
-    [0x1E] = KBD_KEY_A,
-    [0x1F] = KBD_KEY_S,
-    [0x20] = KBD_KEY_D,
-    [0x21] = KBD_KEY_F,
-    [0x22] = KBD_KEY_G,
-    [0x23] = KBD_KEY_H,
-    [0x24] = KBD_KEY_J,
-    [0x25] = KBD_KEY_K,
-    [0x26] = KBD_KEY_L,
-    [0x27] = KBD_KEY_SEMICOLON,
-    [0x28] = KBD_KEY_APOSTROPH,
-    [0x29] = KBD_KEY_GRAVE_ACCENT,
-    [0x2A] = KBD_KEY_LSHIFT,
-    [0x2B] = KBD_KEY_BACK_SLASH,
-    [0x2C] = KBD_KEY_Z,
-    [0x2D] = KBD_KEY_X,
-    [0x2E] = KBD_KEY_C,
-    [0x2F] = KBD_KEY_V,
-    [0x30] = KBD_KEY_B,
-    [0x31] = KBD_KEY_N,
-    [0x32] = KBD_KEY_M,
-    [0x33] = KBD_KEY_COMMA,
-    [0x34] = KBD_KEY_PERIOD,
-    [0x35] = KBD_KEY_SLASH,
-    [0x36] = KBD_KEY_RSHIFT,
-    [0x37] = KBD_KP_KEY_ASTERISK,
-    [0x38] = KBD_KEY_LALT,
-    [0x39] = KBD_KEY_SPACE,
-    [0x3A] = KBD_KEY_CAPS_LOCK,
-    [0x3B] = KBD_KEY_F1,
-    [0x3C] = KBD_KEY_F2,
-    [0x3D] = KBD_KEY_F3,
-    [0x3E] = KBD_KEY_F4,
-    [0x3F] = KBD_KEY_F5,
-    [0x40] = KBD_KEY_F6,
-    [0x41] = KBD_KEY_F7,
-    [0x42] = KBD_KEY_F8,
-    [0x43] = KBD_KEY_F9,
-    [0x44] = KBD_KEY_F10,
-    [0x45] = KBD_KEY_NUMLOCK,
-    [0x46] = KBD_KEY_SCROLL_LOCK,
-    [0x47] = KBD_KP_KEY_7,
-    [0x48] = KBD_KP_KEY_8,
-    [0x49] = KBD_KP_KEY_9,
-    [0x4A] = KBD_KP_KEY_MINUS,
-    [0x4B] = KBD_KP_KEY_4,
-    [0x4C] = KBD_KP_KEY_5,
-    [0x4D] = KBD_KP_KEY_6,
-    [0x4E] = KBD_KP_KEY_PLUS,
-    [0x4F] = KBD_KP_KEY_1,
-    [0x50] = KBD_KP_KEY_2,
-    [0x51] = KBD_KP_KEY_3,
-    [0x52] = KBD_KP_KEY_0,
-    [0x53] = KBD_KP_KEY_PERIOD,
-    [0x57] = KBD_KEY_F11,
-    [0x58] = KBD_KEY_F12
-};
-
-static const uint8_t KBD_ESCAPED_SCAN_TABLE[KBD_NSCANS] = {
-    [0x1C] = KBD_KP_KEY_ENTER,
-    [0x1D] = KBD_KEY_RCTRL,
-    [0x35] = KBD_KP_KEY_SLASH,
-    [0x38] = KBD_KEY_RALT,
-    [0x48] = KBD_KEY_UP,
-    [0x49] = KBD_KEY_PAGE_UP,
-    [0x4B] = KBD_KEY_LEFT,
-    [0x4D] = KBD_KEY_RIGHT,
-    [0x4F] = KBD_KEY_PAGE_DOWN,
-    [0x50] = KBD_KEY_DOWN,
-    [0x51] = KBD_KEY_PAGE_DOWN,
-    [0x52] = KBD_KEY_INSERT,
-    [0x53] = KBD_KEY_DELETE
-};
-
 void keyboard_init();
 
 #endif /* endif MOLTAROS_KEYBOARD_H */