From 89ceb12ff923ad3c2c714f8e1a40130cd99b73ff Mon Sep 17 00:00:00 2001
From: olemorud <ole.kristian.morud@cern.ch>
Date: Thu, 22 Jun 2023 17:35:48 +0200
Subject: [PATCH] Add rule110.sed

`rule110.sed` is an executable sed script that calculates the next
iteration of rule 110 cellular automaton. E.g. `./rule110.sed <<<0001`
outputs `0011`.
---
 rule110.sed | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)
 create mode 100755 rule110.sed

diff --git a/rule110.sed b/rule110.sed
new file mode 100755
index 0000000..443e61f
--- /dev/null
+++ b/rule110.sed
@@ -0,0 +1,21 @@
+#!/usr/bin/sed -Ef
+
+# Translate to intermediate step
+# - Lowercase means previous state was 0
+# - Uppercase means previous state was 1
+# - [Aa] means new state is 1
+# - [Bb] means new state is 0
+# - Assume edges are 0
+:a
+s/([B1])1([B1$])/\1B\2/g # 111 -> 0
+t a
+:b
+s/([B1])0([B1$])/\1a\2/g # 101 -> 1
+t b
+:c
+s/([a0^])0([B1$])/\1a\2/g # 001 -> 1
+t c
+
+# Translate to final results
+s/a/1/g
+s/B/0/g