improve screen flickering on fbcons

src/dev/framebuffer/console.rs

@@ -1,4 +1,4 @@
-use crate::dev::framebuffer::{fb_clearscreen, fb_write_char_array};
+use crate::dev::framebuffer::{fb_clear_area, fb_clearscreen, fb_write_char_array};
 use crate::spinlock::Spinlock;
 use crate::trafficcontrol::TrafficControl;
 
@@ -6,6 +6,7 @@ pub struct FramebufferConsole {
     pub buffer: [[char; 20]; 15], // our font is 16x16, 320x240 is the standard res, so 20x15
     pub cursor: (usize, usize),   // (x, y)
     pub need_screen_clear: bool,
+    pub need_line_clear: bool,
 }
 
 pub static FBCONSOLE: Spinlock<FramebufferConsole> = Spinlock::new(FramebufferConsole::empty());
@@ -16,6 +17,7 @@ impl FramebufferConsole {
             buffer: [[' '; 20]; 15],
             cursor: (0, 0),
             need_screen_clear: true,
+            need_line_clear: false,
         }
     }
 
@@ -31,10 +33,10 @@ impl FramebufferConsole {
 
     // DOES send a framebuffer update!
     pub fn clear_terminal(&mut self, tc: &mut TrafficControl) {
-        self.need_screen_clear = false;
+        self.need_screen_clear = true;
         self.buffer = [[' '; 20]; 15];
         self.cursor = (0, 0);
-        self.render(tc);
+        self.render(tc, true);
     }
 
     // DOES send a framebuffer update!
@@ -54,7 +56,7 @@ impl FramebufferConsole {
             if c == '\x08' {
                 was_special_char = true;
                 // we don't clear the character, that's up to the terminal
-                self.need_screen_clear = true;
+                self.need_line_clear = true;
                 if self.cursor.0 > 0 {
                     self.cursor.0 -= 1;
                 } else {
@@ -79,14 +81,18 @@ impl FramebufferConsole {
             }
         }
 
-        self.render(tc);
+        self.render(tc, false);
     }
 
-    pub fn render(&mut self, tc: &mut TrafficControl) {
+    pub fn render(&mut self, tc: &mut TrafficControl, refresh_whole_screen: bool) {
         if self.need_screen_clear {
-            fb_clearscreen(tc);
+            fb_clearscreen(tc, refresh_whole_screen);
             self.need_screen_clear = false;
         }
+        if self.need_line_clear {
+            fb_clear_area(tc, 0, self.cursor.1 * 16, 320, 16);
+            self.need_line_clear = false;
+        }
 
         for (y, line) in self.buffer.iter().enumerate() {
             fb_write_char_array(tc, 0, y * 16, line);

src/dev/framebuffer/mod.rs

@@ -81,7 +81,7 @@ pub fn fb_write_char_array(tc: &mut TrafficControl, mut x: usize, y: usize, char
     );
 }
 
-pub fn fb_clearscreen(tc: &mut TrafficControl) {
+pub fn fb_clearscreen(tc: &mut TrafficControl, send_refresh: bool) {
     const BYTES: [u8; 3] = FB_BG_COLOR.to_bytes();
     let fbaddr = FRAMEBUFFER_ADDR.load(Ordering::Relaxed);
     if fbaddr == 0 {
@@ -96,6 +96,34 @@ pub fn fb_clearscreen(tc: &mut TrafficControl) {
             }
         }
     }
+    if send_refresh {
+        framebuffer_update(
+            tc,
+            0,
+            0,
+            FRAMEBUFFER_WIDTH as u32,
+            FRAMEBUFFER_HEIGHT as u32,
+        );
+    }
+}
+
+pub fn fb_clear_area(tc: &mut TrafficControl, x: usize, y: usize, w: usize, h: usize) {
+    const BYTES: [u8; 3] = FB_BG_COLOR.to_bytes();
+    let fbaddr = FRAMEBUFFER_ADDR.load(Ordering::Relaxed);
+    if fbaddr == 0 {
+        return;
+    }
+    let fbstride = FRAMEBUFFER_BPP.load(Ordering::Relaxed) * FRAMEBUFFER_WIDTH;
+    for row in 0..h {
+        for col in 0..w {
+            unsafe {
+                unsafe {
+                    let fb = (fbaddr as *mut u8).add(((y+row) * fbstride) + ((x+col) * 4)) as *mut u32;
+                    fb.write_volatile(u32::from_ne_bytes([0, BYTES[0], BYTES[1], BYTES[2]]));
+                }
+            }
+        }
+    }
     framebuffer_update(
         tc,
         0,

src/trafficcontrol.rs

@@ -251,6 +251,8 @@ pub fn handle_syscall(
                             uart.putstr("using framebuffer console\n");
                         }
                     }
+                    let mut fbcons = crate::dev::framebuffer::console::FBCONSOLE.lock();
+                    fbcons.clear_terminal(&mut tc);
                 }
                 0
             }