From a911d97781b2969fee4948349310950bf2318027 Mon Sep 17 00:00:00 2001
From: Alvie Rahman <alvierahman90@gmail.com>
Date: Thu, 12 Oct 2023 18:43:11 +0100
Subject: [PATCH] add TestEncoderAAR.c

---
 Lab_1/TestEncoderAAR.c | 121 +++++++++++++++++++++++++++++++++++++++++
 1 file changed, 121 insertions(+)
 create mode 100644 Lab_1/TestEncoderAAR.c

diff --git a/Lab_1/TestEncoderAAR.c b/Lab_1/TestEncoderAAR.c
new file mode 100644
index 0000000..21f380a
--- /dev/null
+++ b/Lab_1/TestEncoderAAR.c
@@ -0,0 +1,121 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#define bool int
+#define byte unsigned char
+#define numChars  32
+
+// Here we are using global variables simply to be compatible with the Arduino program structure
+// This is REALLY bad practice so please don't do it otherwise!
+long int count = 0;
+long int error = 0;
+
+enum states {state1=1, state2, state3, state4};
+bool channelAState=0;
+bool channelBState=0;
+
+enum states state;
+char receivedChars[numChars]="00";   // an array to store the received data
+
+void initialiseEncoderStateMachine();
+void updateEncoderStateMachine();
+enum states get_state();
+
+int main()
+{
+    // Replicates the setup in Arduino
+    printf("Enter a pair of characters representing initial states of channels A and B\n");
+    scanf("%s",receivedChars);
+    channelAState = receivedChars[0]!='0';
+    channelBState = receivedChars[1]!='0';
+
+    initialiseEncoderStateMachine();
+    printf("State %d, count %ld, error %ld\n", state, count, error);
+    printf("Enter a pair of characters representing channels A and B, enter 99 to end\n");
+
+    // Replicates the loop in Arduino
+    do
+    {
+        scanf("%s",receivedChars);
+        if (strcmp(receivedChars, "99")==0)
+        {
+            break;
+        }
+        channelAState = receivedChars[0]!='0';
+        channelBState = receivedChars[1]!='0';
+        updateEncoderStateMachine();
+        printf("State %d, count %ld, error %ld\n", state, count, error);
+
+    }
+    while(1);
+    return 0;
+}
+
+
+enum states get_state()
+{
+	/* If A is 0 and B is 0, system is in State 1
+	   If A is 1 and B is 0, system is in State 2
+	   If A is 1 and B is 1, system is in State 3
+	   If A is 0 and B is 1, system is in State 4 */
+
+	if (channelAState    && channelBState)    return state3;
+	if (channelAState    && (!channelBState)) return state2;
+	if ((!channelAState) && channelBState)    return state4;
+	if ((!channelAState) && (!channelBState)) return state1;
+
+	return state1; // silences clang-diagnostic-return-type warning
+}
+
+
+void initialiseEncoderStateMachine()
+{
+	state = get_state();
+}
+
+
+void updateEncoderStateMachine()
+{
+	enum states new_state = get_state(); // get new state, don't update state yet so states can be compared
+
+	switch (state)
+	{
+	case state1:
+		// check new state is valid, coming from state1, increment error count if not
+		// adjust count as appropriate if new state is valid
+		switch (new_state) {
+			case state1: break;
+			case state2: count++; break;
+			case state3: error++; break;
+			case state4: count--; break;
+		}
+
+		break;
+	case state2:
+		switch (new_state) {
+			case state1: count--; break;
+			case state2: break;
+			case state3: count++; break;
+			case state4: error++; break;
+		}
+		break;
+	case state3:
+		switch (new_state) {
+			case state1: error++; break;
+			case state2: count--; break;
+			case state3: break;
+			case state4: count++; break;
+		}
+		break;
+	case state4:
+		switch (new_state) {
+			case state1: count++; break;
+			case state2: error++; break;
+			case state3: count--; break;
+			case state4: break;
+		}
+		break;
+	}
+
+	state = new_state; // set new state
+}