Multi-line support in printf

src/kernel.cpp

@@ -11,9 +11,34 @@
 
 void printf(char* str) {
     static uint16_t* VideoMemory = (uint16_t*)0xb8000;
+    static uint8_t x = 0, y = 0;
 
-    for (int i = 0; str[i] != '\0'; ++i)
-        VideoMemory[i] = (VideoMemory[i] & 0xFF00) | str[i];
+    for (int i = 0; str[i] != '\0'; ++i) {
+        switch (str[i]) {
+            case '\n':
+                y++;
+                x = 0;
+                break;
+            default:
+                VideoMemory[80 * y + x] = (VideoMemory[80 * y + x] & 0xFF00) | str[i];
+                x++;
+                break;
+        }
+
+        //line feed after 80 chars (terminal width)
+        if (x >= 80) {
+            y++;
+            x = 0;
+        }
+        //we've reached max screen rows
+        if (y > 25) {
+            for (y = 0; y < 25; y++) {
+                for (x - 0; x < 80; x++) {
+                    VideoMemory[80 * y + x] = (VideoMemory[80 * y + x] & 0xFF00) | ' ';
+                }
+            }
+        }
+    }
 }
 
 typedef void (*constructor)();
@@ -25,7 +50,10 @@ extern "C" void call_constructors() {
 }
 
 extern "C" void ferglos_Main(const void* multiboot_structure, uint32_t /*mb_mag*/) {
-    printf("Welcome to FerglOS v0.0.1!");
+    printf("Welcome to FerglOS v0.0.2!\n");
+    printf("Hitler blinks.");
+
+    GlobalDescriptorTable gdt;
     while (1)
         ;
 }