Remove redundant constant

res/config.ini

@@ -35,6 +35,14 @@
 # matrix -> CMatrix
 animation = none
 
+# The minimum time between animation frames
+# 32 -> ~30fps
+# 16 -> ~60fps
+# 8  -> ~120fps
+# 6  -> ~144fps
+# 4  -> ~240fps
+animation_refresh_ms = 16
+
 # Stop the animation after some time
 # 0 -> Run forever
 # 1..2e12 -> Stop the animation after this many seconds

src/animations/Doom.zig

@@ -50,35 +50,57 @@ pub fn realloc(self: *Doom) !void {
     self.buffer = buffer;
 }
 
-pub fn draw(self: Doom) void {
+pub fn drawWithUpdate(self: Doom) void {
     for (0..self.terminal_buffer.width) |x| {
         for (1..self.terminal_buffer.height) |y| {
+            // get source index
             const source = y * self.terminal_buffer.width + x;
+
+            // random number between 0 and 3 inclusive
             const random = (self.terminal_buffer.random.int(u16) % 7) & 3;
 
+            // adjust destination index based on random value
             var dest = (source - @min(source, random)) + 1;
             if (self.terminal_buffer.width > dest) dest = 0 else dest -= self.terminal_buffer.width;
 
+            // get source intensity and destination offset
             const buffer_source = self.buffer[source];
             const buffer_dest_offset = random & 1;
 
             if (buffer_source < buffer_dest_offset) continue;
 
+            // calculate  the destination intensity
             var buffer_dest = buffer_source - buffer_dest_offset;
             if (buffer_dest > 12) buffer_dest = 0;
             self.buffer[dest] = @intCast(buffer_dest);
 
+            // update terminal
             self.terminal_buffer.buffer[dest] = toTermboxCell(FIRE[buffer_dest]);
             self.terminal_buffer.buffer[source] = toTermboxCell(FIRE[buffer_source]);
         }
     }
 }
 
-fn initBuffer(buffer: []u8, width: usize) void {
-    const length = buffer.len - width;
-    const slice_start = buffer[0..length];
-    const slice_end = buffer[length..];
+pub fn draw(self: Doom) void {
+    for (0..self.terminal_buffer.width) |x| {
+        for (1..self.terminal_buffer.height) |y| {
+            // get source index
+            const source = y * self.terminal_buffer.width + x;
 
+            // get intensity from buffer
+            const buffer_source = self.buffer[source];
+
+            // set cell to correct fire char
+            self.terminal_buffer.buffer[source] = toTermboxCell(FIRE[buffer_source]);
+        }
+    }
+}
+
+fn initBuffer(buffer: []u8, width: usize) void {
+    const slice_start = buffer[0..buffer.len];
+    const slice_end = buffer[buffer.len - width .. buffer.len];
+
+    // set cell initial values to 0, set bottom row to be fire sources
     @memset(slice_start, 0);
     @memset(slice_end, STEPS - 1);
 }

src/animations/Matrix.zig

@@ -68,14 +68,12 @@ pub fn realloc(self: *Matrix) !void {
     self.lines = lines;
 }
 
-pub fn draw(self: *Matrix) void {
+pub fn drawWithUpdate(self: *Matrix) void {
     const buf_height = self.terminal_buffer.height;
     const buf_width = self.terminal_buffer.width;
-    self.count += 1;
-    if (self.count > FRAME_DELAY) {
+
     self.frame += 1;
     if (self.frame > 4) self.frame = 1;
-        self.count = 0;
 
     var x: usize = 0;
     while (x < self.terminal_buffer.width) : (x += 2) {
@@ -140,7 +138,12 @@ pub fn draw(self: *Matrix) void {
             first_col = false;
         }
     }
-    }
+
+    self.draw();
+}
+
+pub fn draw(self: *Matrix) void {
+    const buf_width = self.terminal_buffer.width;
 
     var x: usize = 0;
     while (x < buf_width) : (x += 2) {

src/config/Config.zig

@@ -8,6 +8,7 @@ const Bigclock = enums.Bigclock;
 
 animation: Animation = .none,
 animation_timeout_sec: u12 = 0,
+animation_refresh_ms: u16 = 16,
 asterisk: ?u8 = '*',
 auth_fails: u64 = 10,
 bg: u16 = 0,

src/main.zig

@@ -317,6 +317,11 @@ pub fn main() !void {
         }
     }
 
+    var animation_timer = switch (config.animation) {
+        .none => undefined,
+        else => try std.time.Timer.start(),
+    };
+
     const animate = config.animation != .none;
     const shutdown_key = try std.fmt.parseInt(u8, config.shutdown_key[1..], 10);
     const shutdown_len = try utils.strWidth(lang.shutdown);
@@ -380,8 +385,22 @@ pub fn main() !void {
                 if (!animation_timed_out) {
                     switch (config.animation) {
                         .none => {},
-                        .doom => doom.draw(),
-                        .matrix => matrix.draw(),
+                        .doom => {
+                            if (animation_timer.read() / std.time.ns_per_ms > config.animation_refresh_ms) {
+                                animation_timer.reset();
+                                doom.drawWithUpdate();
+                            } else {
+                                doom.draw();
+                            }
+                        },
+                        .matrix => {
+                            if (animation_timer.read() / std.time.ns_per_ms > config.animation_refresh_ms) {
+                                animation_timer.reset();
+                                matrix.drawWithUpdate();
+                            } else {
+                                matrix.draw();
+                            }
+                        },
                     }
                 }
 
@@ -685,7 +704,7 @@ pub fn main() !void {
                     const password_text = try allocator.dupeZ(u8, password.text.items);
                     defer allocator.free(password_text);
 
-                    // Give up control on the TTY
+                    // Give up TTY
                     _ = termbox.tb_shutdown();
 
                     session_pid = try std.posix.fork();
@@ -702,10 +721,13 @@ pub fn main() !void {
                     session_pid = -1;
                 }
 
-                // Take back control of the TTY
+                // Take back TTY
                 _ = termbox.tb_init();
                 _ = termbox.tb_set_output_mode(termbox.TB_OUTPUT_NORMAL);
 
+                // Reinitialise buffer to avoid use after free
+                buffer = TerminalBuffer.init(config, labels_max_length, random);
+
                 const auth_err = shared_err.readError();
                 if (auth_err) |err| {
                     auth_fails += 1;