Implemented a basic shell

src/kernel/entry.asm

@@ -11,6 +11,12 @@ _start:
     pop ax
     mov [driveNum], al
     call main
+    
+    ; Exit QEMU
+    mov ax, 0x2000
+    mov dx, 0x0604
+    out dx, ax
+
     jmp $       ;; If we used cli, hlt we wouldn't have interrupts :/
 
 [global driveNum]

src/kernel/main.c

@@ -8,6 +8,8 @@
 #include "disk.h"
 #include "string.h"
 
+#define PROMPT "#> "
+
 void main() {
     // Interrupts
     setupIdt();
@@ -22,12 +24,42 @@ void main() {
 
     clear(0x0f);
     print("kern.\n\n", 0x0f);
+    
+    // Run Interactive Shell Program
+    // TODO: Make it in another file
 
     while (1) {
-        print("> ", 0x0e);
+        print(PROMPT, 0x0a);
         char* input = read('\n', 0x0f);
-        if (*input == '\n') continue;
+        
-        print(input, 0x0b);
+        if (input[0] == '\n') continue;
+        
+        char* args;
+        if ((args = strchr(input, ' ')) == NULL) {
+            args = strchr(input, '\n');
+        }
+
+        *args = '\0';
+        args++;
+
+        if (strcmp(input, "clear") == 0) {
+            clear(0x0f);
+        } else if (strcmp(input, "echo") == 0) {
+            print(args, 0x0f);
+        } else if (strcmp(input, "exit") == 0) {
+            break;
+        } else if (strcmp(input, "help") == 0) {
+            print("Available Commands:\n", 0x0f);
+            print(" clear      | Clears the screen\n", 0x0f);
+            print(" echo       | Prints a message to stdout\n", 0x0f);
+            print(" exit       | Exits program\n", 0x0f);
+            print(" help       | Prints this message\n", 0x0f);
+            // TODO: print(" ls         | Lists all available files\n", 0x0f);
+            // TODO: print(" reboot     | Reboots the system\n", 0x0f);
+        } else {
+            print("Command not found: ", 0x0c);
+            print(input, 0x0c);
+            putc('\n', 0x0f);
+        }
     }
 }
-

src/kernel/system.c

@@ -11,16 +11,6 @@ void outb(uint16_t port, uint8_t data) {
     asm volatile("out %0, %1" :: "a"(data), "Nd"(port));
 }
 
-uint16_t inw(uint16_t port) {
-    uint8_t result;
-    asm volatile("in %1, %0" : "=a"(result) : "Nd"(port));
-    return result;
-}
-
-void outw(uint16_t port, uint16_t data) {
-    asm volatile("out %0, %1" :: "a"(data), "Nd"(port));
-}
-
 char* memcopy(char* src, char* dst, uint16_t length) {
     for (int i = 0; i < length; i++) {
         *(dst + i) = *(src + i);
@@ -47,7 +37,3 @@ void hlt() {
     asm volatile("hlt");
 }
 
-void exit() {
-    outw(0x0604, 0x2000);
-}
-

src/kernel/system.h

@@ -6,8 +6,6 @@
 // Port functions
 uint8_t inb(uint16_t port);
 void outb(uint16_t port, uint8_t data);
-uint16_t inw(uint16_t port);
-void outw(uint16_t port, uint16_t data);
 
 // Memory functions
 char* memcopy(char* src, char* dst, uint16_t length);
@@ -18,6 +16,4 @@ void cli();
 void sti();
 void hlt();
 
-void exit();
-
 #endif