From 7bc67b0f725afa15bab8cef1e1bea5f2fb86b543 Mon Sep 17 00:00:00 2001
From: Tom Smeding <tom.smeding@gmail.com>
Date: Sun, 15 Apr 2018 17:16:46 +0200
Subject: Add input reading algorithm

---
 algorithm.txt | 57 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 57 insertions(+)

diff --git a/algorithm.txt b/algorithm.txt
index 82e0d69..109a7b1 100644
--- a/algorithm.txt
+++ b/algorithm.txt
@@ -12,6 +12,63 @@ Tape
 - Each cell: [ 0 | head | tt1 | tt2 | sym ]
 
 
+Read input
+==========
+
+Write 1, move right a rule width
+Go to tr1
+Write 1
+While nonzero:
+	Read into qfrom
+
+	Read into sread
+	Copy to sread+1 (scratch sread+2)
+	Write 1 to sread+2
+	Subtract 32 from sread+1 and go to sread+1
+	While nonzero:
+		Subtract 1 from sread+2
+		Zero sread+1 and go to sread+1
+	Go to sread+2
+	While nonzero:
+		Zero sread
+		Zero sread+2 and go to sread+2
+	Go to sread
+
+	Read into qto
+
+	Read into swrite
+	Copy to swrite+1 (scratch swrite+2)
+	Write 1 to swrite+2
+	Subtract 32 from swrite+1 and go to swrite+1
+	While nonzero:
+		Subtract 1 from swrite+2
+		Zero swrite+1 and go to swrite+1
+	Go to swrite+2
+	While nonzero:
+		Zero swrite
+		Zero swrite+2 and go to swrite+2
+	Go to swrite
+
+	Read into dir
+	Subtract '=' (61) from dir
+	Copy qfrom to tr4 (using tr3 as scratch)
+	Go to tr4
+	While nonzero:
+		Add 1
+		While nonzero:
+			Write 1 to rightrule.tr1
+			Zero tr4
+		Zero tr4
+
+	Go to rightrule.tr1, which is 1 precisely if we didn't have EOF
+
+Now at a zero tr1 that is really the qcurrent of Mmarker
+Write 'S' (83), and go to Mmarker.0
+Write 1
+Set rightcell.head to 1
+Go back to Mmarker.0
+
+
 Execution step
 ==============
 
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