almost got a complete mode switch (vga graphics back to text) working

some cleanup in VGA driver code

3 files changed, 25 insertions, 13 deletions

diff --git a/src/kernel/kernel.c b/src/kernel/kernel.c
index 9bd3d98..501ab90 100644
--- a/src/kernel/kernel.c
+++ b/src/kernel/kernel.c
@@ -143,6 +143,8 @@ void kernel_main( void )
 
 		switch( global_context.mode ) {
 			case MODE_TEXT:
+				// nothing to draw or refresh in text mode, the
+				// VGA card is doing that for us
 				break;
 
 			case MODE_GRAPHICS:
@@ -150,12 +152,6 @@ void kernel_main( void )
 				// events originating especially from the mouse
 				interrupts_disable( );
 
-				// wait for VGA retrace, assume drawing the desktop
-				// is fast enough to finish in time (so we don't recheck
-				// for retrace), it Z-buffering, this is done in vga_refresh
-				// directly, no need to do it here
-//				vga_wait_for_retrace( &global_context.vga );
-
 				// as vga_t is equals to the graphical context for now
 				((widget_vtable_t *)global_context.desktop.vtable)->draw( &global_context.desktop, &global_context.vga );
 
@@ -230,6 +226,8 @@ static void handle_keyboard_event( keyboard_event_t *event, void *context )
 					switch( global_context->mode ) {
 						case MODE_TEXT:
 							if( vga_set_mode( vga, vga_make_mode( VGA_MODE_TYPE_GRAPHICS, 320, 200, 8 ) ) ) {
+								vga_text_save( vga_text );
+
 								desktop_init( &global_context->desktop, 320, 200, VGA_COLOR_BLUE );
 
 								window_init( &global_context->window1, (widget_t *)&global_context->desktop, 60, 90, 60, 70, VGA_COLOR_LIGHT_GREY );
@@ -258,13 +256,13 @@ static void handle_keyboard_event( keyboard_event_t *event, void *context )
 							// enable Z buffering
 							vga_use_z_buffer( &global_context->vga, true );
 
-							// draw on mode switch
-//							((widget_vtable_t *)global_context->desktop.vtable)->draw( &global_context->desktop, &global_context->vga );
-
 							global_context->mode = MODE_GRAPHICS;
 							break;
 
 						case MODE_GRAPHICS:
+							vga_text_restore( vga_text );
+							vga_text_set_cursor( vga_text, vga_text->cursor_x, vga_text->cursor_y );
+
 							if( vga_set_mode( vga, vga_make_mode( VGA_MODE_TYPE_TEXT, 640, 480, 4 ) ) ) {
 								mouse_set_resolution( mouse, vga_text->res_x, vga_text->res_y );
 								global_context->mode = MODE_TEXT;
@@ -336,10 +334,6 @@ static void handle_mouse_event( mouse_event_t *event, void *context )
 					break;
 			}
 
-			// alternative way of redrawing on mouse event
-			// on qemu looses the mouse..
-//			((widget_vtable_t *)desktop->vtable)->draw( &global_context->desktop, &global_context->vga );
-
 			break;
 	}
 }
diff --git a/src/kernel/vgatext.c b/src/kernel/vgatext.c
index 76bfd46..232d91a 100644
--- a/src/kernel/vgatext.c
+++ b/src/kernel/vgatext.c
@@ -262,3 +262,16 @@ void vga_text_hide_mouse_cursor( vga_text_t *vga_text )
 	}
 }
 
+void vga_text_save( vga_text_t *vga_text )
+{
+	volatile uint8_t *VIDEO_MEMORY = (uint8_t *)0xA0000;
+
+	memcpy( vga_text->buf, VIDEO_MEMORY, 2*65535 );
+}
+
+void vga_text_restore( vga_text_t *vga_text )
+{
+	volatile uint8_t *VIDEO_MEMORY = (uint8_t *)0xA0000;
+
+	memcpy( VIDEO_MEMORY, vga_text->buf, 2*65535 );
+}
diff --git a/src/kernel/vgatext.h b/src/kernel/vgatext.h
index 499e3d8..c0bfbdc 100644
--- a/src/kernel/vgatext.h
+++ b/src/kernel/vgatext.h
@@ -42,6 +42,9 @@ typedef struct {
 	bool show_mouse_cursor;
 	int mouse_cursor_x;
 	int mouse_cursor_y;
+	// TODO: actually restore a proper, for now we
+	// remember the whole video area during mode switch
+	uint8_t buf[2*65535];
 } vga_text_t;
 
 void vga_text_init( vga_text_t *vga_text );
@@ -64,5 +67,7 @@ void vga_text_inverse_colors_at( vga_text_t *vga_text, const int x, const int y
 void vga_text_show_mouse_cursor( vga_text_t *vga_text );
 void vga_text_move_mouse_cursor( vga_text_t *vga_text, const int x, const int y );
 void vga_text_hide_mouse_cursor( vga_text_t *vga_text );
+void vga_text_save( vga_text_t *vga_text );
+void vga_text_restore( vga_text_t *vga_text );
  
 #endif /* VGA_TEXT_H */