From 3c64c9b0e9da1b81d6fcf93bceaae305a2709b65 Mon Sep 17 00:00:00 2001
From: Fractal147 <35138372+Fractal147@users.noreply.github.com>
Date: Fri, 8 Jan 2021 03:17:41 +0000
Subject: [PATCH] Fix stepper half half step mode (#1397)

* Fixed half half step mode

Half step mode originally had second and third steps mixed up for output A.
https://github.com/esphome/issues/issues/1655

* Updated half step mode to have no branching

Code based off comments in PR: https://github.com/esphome/esphome/pull/1397#issuecomment-739413973

* removed variable declarations in the switch/case

Oops. No explicit declarations.
Rearranged to be tidier, same output sequence.

* Fixed typo bracket

Minor typo fixed - logic complete to do branchless half stepping.

* Format the brackets to satisfy clang
---
 esphome/components/uln2003/uln2003.cpp | 10 ++--------
 1 file changed, 2 insertions(+), 8 deletions(-)

diff --git a/esphome/components/uln2003/uln2003.cpp b/esphome/components/uln2003/uln2003.cpp
index b1a397ad6c..38eadc9dc8 100644
--- a/esphome/components/uln2003/uln2003.cpp
+++ b/esphome/components/uln2003/uln2003.cpp
@@ -70,14 +70,8 @@ void ULN2003::write_step_(int32_t step) {
     }
     case ULN2003_STEP_MODE_HALF_STEP: {
       // A, AB, B, BC, C, CD, D, DA
-      if (i == 0 || i == 2 || i == 7)
-        res |= 1 << 0;
-      if (i == 1 || i == 2 || i == 3)
-        res |= 1 << 1;
-      if (i == 3 || i == 4 || i == 5)
-        res |= 1 << 2;
-      if (i == 5 || i == 6 || i == 7)
-        res |= 1 << 3;
+      res |= 1 << (i >> 1);
+      res |= 1 << (((i + 1) >> 1) & 0x3);
       break;
     }
     case ULN2003_STEP_MODE_WAVE_DRIVE: {