Add text colour manipulation

1 files changed, 42 insertions, 0 deletions

diff --git a/kernel/io/vga/text_mode_display.c b/kernel/io/vga/text_mode_display.c
new file mode 100644
index 0000000..958eb87
--- /dev/null
+++ b/kernel/io/vga/text_mode_display.c
@@ -0,0 +1,42 @@
+#include "colours.h"
+
+#define COLS (80 * 2) // 2 bytes per char
+#define ROWS 25
+#define FRAME_SIZE (ROWS * COLS)
+
+char *video_ram = (char *)0xB8000;
+int cursor_pos = 0;
+int char_attribute_byte = 0x07;
+
+void clear_screen()
+{
+  for (int i = 0; i < FRAME_SIZE; i = i + 2)
+  {
+    video_ram[i] = ' ';
+    video_ram[i + 1] = char_attribute_byte;
+  };
+  cursor_pos = 0;
+}
+
+void print(char *msg)
+{
+  int j = 0;
+  while (msg[j] != '\0')
+  {
+    video_ram[cursor_pos++] = msg[j];
+    video_ram[cursor_pos++] = char_attribute_byte;
+    ++j;
+  }
+}
+
+void print_ln(char *msg)
+{
+  print(msg);
+  int current_line = cursor_pos / COLS;
+  cursor_pos = (current_line + 1) * COLS;
+}
+
+void set_text_colour(int foreground, int background) 
+{
+  char_attribute_byte = (background << 4) | foreground;
+}
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