From: Tilman Sauerbeck <tilman@code-monkey.de>
Date: Mon, 30 Dec 2019 17:18:08 +0000 (+0100)
Subject: common: Tweak bit order of screen data.
X-Git-Url: http://git.code-monkey.de/?p=gps-watch.git;a=commitdiff_plain;h=9a546fcb6aaae061f51546dd538883a99c419fce

common: Tweak bit order of screen data.

The left-most pixel is now defined by the most significant bit.
This is a more intuitive representation than what we had before.
---

diff --git a/src/common/display.rs b/src/common/display.rs
index 04f6c35..38eeaa9 100644
--- a/src/common/display.rs
+++ b/src/common/display.rs
@@ -157,10 +157,10 @@ impl Display {
     }
 
     pub fn draw(&mut self, screen: &screen::Screen) {
-        let mut mask : u8 = 0x80;
+        let mut mask : u8 = 0x01;
 
         for col in 0..screen::WIDTH_PX {
-            mask = mask.rotate_left(1);
+            mask = mask.rotate_right(1);
 
             // Rotate by 90 degrees.
             //
diff --git a/src/common/screen.rs b/src/common/screen.rs
index 71425c4..3b890a1 100644
--- a/src/common/screen.rs
+++ b/src/common/screen.rs
@@ -29,6 +29,8 @@ pub const WIDTH_BYTES: usize = (WIDTH_PX as usize + 7) / 8;
 pub const SIZE_BYTES: usize = HEIGHT_PX as usize * WIDTH_BYTES;
 
 pub struct Screen {
+    // Each byte corresponds to 8 pixels, with the MSB referring
+    // to the left-most pixel.
     pixels: [u8; SIZE_BYTES],
 }