From be01760c32a00276e2d7c9f526b97d7e1b249743 Mon Sep 17 00:00:00 2001
From: Verkehrsrot <cyberman@obh.snafu.de>
Date: Tue, 1 Oct 2019 13:35:05 +0200
Subject: [PATCH] pax curve plotter

---
 src/display.cpp | 11 ++++-------
 1 file changed, 4 insertions(+), 7 deletions(-)

diff --git a/src/display.cpp b/src/display.cpp
index 8b7564e1..9662dc3f 100644
--- a/src/display.cpp
+++ b/src/display.cpp
@@ -397,18 +397,15 @@ void oledfillRect(uint16_t x, uint16_t y, uint16_t width, uint16_t height,
 int oledDrawPixel(uint8_t *buf, const uint16_t x, const uint16_t y,
                   const uint8_t dot) {
 
-  uint8_t page, bit;
-
   if (x > DISPLAY_WIDTH || y > DISPLAY_HEIGHT)
     return -1;
 
-  page = y / 8;
-  bit = y % 8;
+  uint8_t bit = y & 7;
+  uint16_t idx = y / 8 * DISPLAY_WIDTH + x;
 
+  buf[idx] &= ~(1 << bit); // clear pixel
   if (dot)
-    buf[page * DISPLAY_WIDTH + x] |= (1 << bit); // mark
-  else
-    buf[page * DISPLAY_WIDTH + x] &= ~(0 << bit); // clear
+    buf[idx] |= (1 << bit); // set pixel
 
   return 0;
 }