1 files changed, 36 insertions, 0 deletions
diff --git a/kernel.c b/kernel.c
new file mode 100644
index 0000000..190d36e
--- /dev/null
+++ b/kernel.c
@@ -0,0 +1,36 @@
+#include <stddef.h>
+#include <stdint.h>
+
+#define WIDTH 80
+#define HEIGHT 25
+
+#define BLACK 0
+#define BLUE 1
+#define GREEN 2
+#define RED 4
+#define MAGENTA 13
+#define WHITE 15
+
+int strlen(char* s) {
+  int n = 0;
+  char* s_ptr = s;
+  while (*(s_ptr++)) { 
+    n++;
+  }
+  return n;
+}
+
+void kernel(void) {
+  uint16_t* vgamem = (uint16_t*) 0xB8000;
+  uint16_t vgacolors[6] = {WHITE | RED << 4, WHITE | GREEN << 4, WHITE | BLUE << 4, BLACK | RED << 4, BLACK | GREEN << 4, BLACK | BLUE << 4};
+  char* s = "Hello world!";
+  int i,j,k;
+  for (k = 0; k >= 0; ++k) {
+    k = (k % 5);
+    j = 0;
+    while (j < 100000000) { j++; } // Since we don't have an interrupt descriptor table we can't use the PIC; this emulates "sleeping"
+    for (i = 0; i < WIDTH*HEIGHT; i++) {
+      vgamem[i] = s[i % strlen(s)] | vgacolors[(i+k) % 6] << 8;
+    }
+  }
+}