Now this should be complete

Added basic shell and fixed various bugs...now iceos should be
"complete".

kernel/shell/Makefile

@@ -0,0 +1,10 @@
+OBJS = shell.o
+
+CC = i686-elf-gcc # cross-compiler
+CFLAGS = -m32 -fno-stack-protector -ffreestanding -Wall -Wextra -Werror -g -c
+
+
+all:${OBJS}
+
+%.o: %.c
+	$(CC) $(CFLAGS) $< -o $@

kernel/shell/shell.c

@@ -0,0 +1,87 @@
+#include "shell.h"
+#include "../libc/string.h"
+#include "../libc/stdio.h"
+#include "../drivers/tty.h"
+#include "../drivers/ports.h"
+
+void helper() {
+    puts("\nList of available commands:\n"
+         "\nhelp        - Print this helper"
+         "\nint         - Test some interrupts"
+         "\nbanner      - Show banner"
+         "\nclear, cls  - Clear the screen"
+         "\nabout       - About this kernel"
+         "\nreboot      - Reboot the system"
+        );
+}
+
+void test_interrupts() {
+    // Testing some interrupts
+    asm("int $0"); // Division by zero
+    asm("int $4"); // Stack overflow
+    asm("int $1"); // Page fault 
+}
+
+void about() {
+    printf_color("\n====== IceOS v0.0.1 (c) 2019 Marco 'icebit' Cetica ======\n\n",
+                 LIGHT_CYAN, BLACK);
+    printf_color(
+        "iceOS is a x86 monolithic kernel written in C from scratch.\n"  
+        "This project doesn't aim to be a fully functional operating system\n"
+        "with tons of drivers and graphical applications,\nit's just a learning tool" 
+        "to teach myself concepts like\nOperating Systems, Computer Architecture and Digital Electronics.\n" 
+        "\n\n"
+        "iceOS comes with the following features:\n"
+        "- Bare metal booting;\n"
+        "- VGA driver;\n"
+        "- Interrupts implementation;\n"
+        "- PIC & PIT implementation;\n"
+        "- PS2 driver;\n"
+        "- Support for x86 architecture;\n"
+        "- GRUB as bootloader;\n",
+    LIGHT_GREEN, BLACK);
+}
+
+void reboot() {
+    uint8_t tmp;
+    asm("cli"); // First disable all interrupts
+
+    // Clear keyboard buffers
+    do {
+        tmp = inb(0x64); // Keyboard interface
+        if(check_flag(tmp, 0) != 0)
+            inb(0x60); // Clear keyboard data
+    } while(check_flag(tmp, 1) != 0);
+
+    outb(0x64, 0xFE); // Reset the CPU
+}
+
+void iceos_ascii_logo() {
+    printf_color(
+"\n\n###  #####  ####### #######  #####\n"
+" #  #     # #       #     # #     #\n"
+" #  #       #       #     # #       \n"
+" #  #       #####   #     #  #####  \n"
+" #  #       #       #     #       # \n"
+" #  #     # #       #     # #     # \n"
+"###  #####  ####### #######  #####  \n"
+"\n     (c) Marco Cetica 2019\n",
+ LIGHT_MAGENTA, BLACK);
+ }
+
+void processCommand(uint8_t *cmd) {
+    if(strcmp(cmd, (uint8_t*)"help") == 0)
+        helper();
+    else if(strcmp(cmd, (uint8_t*)"int") == 0)
+        test_interrupts();
+    else if(strcmp(cmd, (uint8_t*)"clear") == 0 || strcmp(cmd, (uint8_t*)"cls") == 0)
+        clear_prompt();
+    else if(strcmp(cmd, (uint8_t*)"about") == 0)
+        about();
+    else if(strcmp(cmd, (uint8_t*)"banner") == 0)
+        iceos_ascii_logo();
+    else if(strcmp(cmd, (uint8_t*)"reboot") == 0)
+        reboot();
+    else
+        puts("\nCommand not found!");
+}

kernel/shell/shell.h

@@ -0,0 +1,20 @@
+/**************************************
+ *          iceOS Kernel              *
+ * Developed by Marco 'icebit' Cetica * 
+ *            (c) 2019                *
+ *       Released under GPLv3         *
+ * https://github.com/ice-bit/iceOS   *
+ ***************************************/
+#ifndef _SHELL_H_
+#define _SHELL_H_
+
+#include <stdint.h>
+
+#define bit(n) (1 << (n))
+#define check_flag(flags, n) ((flags) & bit(n))
+
+void helper();
+void processCommand(uint8_t *cmd);
+void iceos_ascii_logo();
+
+#endif