Added some checks to prevent useless note setting

Author: zment4

src/speaker.c

@@ -17,8 +17,16 @@ static u16 notes[7][12] = {
 };
 
 bool note_playing = false;
+u8 current_note = NOTE_NONE;
+u8 current_octave = 0;
 
 void speaker_note(u8 octave, u8 note) {
+    if (octave == current_octave && note == current_note)
+        return;
+
+    current_octave = octave;
+    current_note = note;
+    
     if (note == NOTE_NONE)
     {
         speaker_pause();

src/stage0.S

@@ -38,7 +38,7 @@ _start:
        How many sectors do we read, value in cx
      */
 
-    movw $0x40, %cx
+    movw $0x23, %cx
     movw $0x1000, segment
     movw $0x0000, offset
     movw $1, sector