From 41c90b30aa0bfeaafe50e83b7c1f87c53fb7a349 Mon Sep 17 00:00:00 2001
From: Gelthor <gelthor-gitea_sm@havnor.org.uk>
Date: Sun, 13 Sep 2026 23:18:11 +0100
Subject: [PATCH] Clearing the screen now switches to the cleared FB

---
 src/screen.asm | 46 +++++++++++++++++++++++++++++++++++-----------
 1 file changed, 35 insertions(+), 11 deletions(-)

diff --git a/src/screen.asm b/src/screen.asm
index 6f5db8a..668197e 100644
--- a/src/screen.asm
+++ b/src/screen.asm
@@ -185,8 +185,21 @@ pub set_graphics_mode:
     pop r8
 
     cmp r5, 0
-    jne clear ; Tail call
-
+    je set_graphics_mode__not_clear
+        ; If double buffering
+        cmp r6, 0
+        je set_graphics_mode__clear_single_fb
+            ; Clear one buffer..
+            push r13
+            counter r13
+            add r13, r13, 12
+            jmp clear_graphics_fb  ; Call
+            pop r13
+            ; ...then the other
+        set_graphics_mode__clear_single_fb:
+        jmp clear_graphics_fb ; Tail call
+    set_graphics_mode__not_clear:
+    
     mov flags, errno.OK
     jmp r13 ; return
 
@@ -202,7 +215,7 @@ set_graphics_mode__error:
 
 pub clear:
 ; void clear()
-; Paints the whole screen black
+; Paints the draw framebuffer black and switches to it
 ;
 ; Arguments:
 ; - None
@@ -213,12 +226,23 @@ pub clear:
 ; - r2: fill_screen
 ; - r3: fill_screen
 ; - r4: fill_screen
+; - r5: Alternate link register
 
+    mov r5, r13
     load_8 flags, [globals.FB_MODE]
-    je clear_graphics_mode
-    ; Fall through into clear_text_mode
+    mov r13, clear__done
+    je clear__graphics
+        jmp clear_text_fb ; Call, return to clear__done
+    clear__graphics:
+        jmp clear_graphics_fb ; Call
+    clear__done:
+        mov r13, r5
+        jmp switch_buffers ; Tail call
+        
+    
+    
 
-pub clear_text_mode:
+pub clear_text_fb:
 ; void clear_text_mode()
 ; Paints the whole text mode screen in the background colour
 ;
@@ -238,7 +262,7 @@ pub clear_text_mode:
     load_8 r4, [globals.FB_LOG_BPP]
     lsl r3, r3, r4 ; Num bytes in FB
     load_32 r2, [globals.FB_DRAW_PTR]
-    add r3, r3, r2 ; End of FB
+    add r3, r3, r2 ; Start of FB
     lsl r4, r3, r4 ; Num bytes in FB
     load_32 r2, [globals.FB_DRAW_PTR]
     add r3, r4, r2 ; End of FB
@@ -246,9 +270,9 @@ pub clear_text_mode:
     jmp fill_screen__loop
 
     
-pub clear_graphics_mode:
-; u16 clear_graphics_mode()
-; Paints the whole graphics mode screen black
+pub clear_graphics_fb:
+; u16 clear_graphics_fb()
+; Paints all of the current graphics mode draw buffer black
 ;
 ; Arguments:
 ; - None
@@ -331,7 +355,7 @@ pub fill_screen:
         jb fill_screen__loop
 
     mov flags, errno.OK
-    jmp r13 ; return
+    jmp switch_buffers ; Tail call
 
 
 pub set_text_mode_default: