Feature/state machine

fsm/README.md

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+# Node State Machine
+fsm.c implements the state machine for the Node subsystem as shown here:
+
+![State_Diagram_14-5-22 (1)](https://user-images.githubusercontent.com/67641046/169704065-c144127e-2833-4674-a9cf-f29355fdd1c9.png)
+
+In order to compile: 
+- Ensure that your gcc version is up to date with gcc --version (my version is 11.2.0).
+- cd into the /fsm subdirectory and do gcc fsm.c -o fsm
+- ./fsm

fsm/fsm.c

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+#include <stdio.h>
+#include <stdbool.h>
+#include <stdlib.h>
+#include <assert.h>
+
+typedef enum
+{
+    BOOT,
+    AUTONOMOUS,
+    MANUAL
+} State;
+
+void get_next_state(char input, State **state);
+void test_fsm();
+
+int main()
+{
+    char input;
+    State * state;
+    State tmp;
+
+    State boot = BOOT;
+
+    state = &boot;
+
+    while (1)
+    {
+        printf("\nCurrent state is: %d\n", *state);
+        printf("Please enter character input: ");
+        scanf("%c", &input);
+        if (input == '\n' || input == EOF)
+        {
+            continue;
+        }
+        if (input == 'q' || input == 'Q')
+        {
+            break;
+        }
+        get_next_state(input, &state);
+        tmp = *state;
+        fflush(stdin);
+        state = &tmp;
+    }
+
+    test_fsm();
+    printf("Unit Test Passed");
+}
+
+// Unit test asserting correct state transitions
+// returns true if pass, false otherwise
+void test_fsm()
+{
+    char input;
+
+    // Test setup
+    State * boot;
+    State boot_val = BOOT;
+    State * autonomous;
+    State autonomous_val = AUTONOMOUS;
+    State * manual;
+    State manual_val = MANUAL;
+
+    // Boot -> Boot transition tests
+    boot = &boot_val;
+    input = 'p';
+    get_next_state(input, &boot);
+    assert(*boot == boot_val);
+
+    boot = &boot_val;
+    input = 'P';
+    get_next_state(input, &boot);
+    assert(*boot == boot_val);
+
+    boot = &boot_val;
+    input = 'w';
+    get_next_state(input, &boot);
+    assert(*boot == boot_val);
+
+    boot = &boot_val;
+    input = 'W';
+    get_next_state(input, &boot);
+    assert(*boot == boot_val);
+
+    // Boot -> Autonomous transition tests
+    boot = &boot_val;
+    input = 'a';
+    get_next_state(input, &boot);
+    assert(*boot == autonomous_val);
+
+    boot = &boot_val;
+    input = 'A';
+    get_next_state(input, &boot);
+    assert(*boot == autonomous_val);
+
+    // Boot -> Manual transition tests
+    boot = &boot_val;
+    input = 'm';
+    get_next_state(input, &boot);
+    assert(*boot == manual_val);
+
+    boot = &boot_val;
+    input = 'M';
+    get_next_state(input, &boot);
+    assert(*boot == manual_val);
+
+    // Autonomous -> Boot transition tests
+    autonomous = &autonomous_val;
+    input = 'p';
+    get_next_state(input, &autonomous);
+    assert(*autonomous == boot_val);
+
+    autonomous = &autonomous_val;
+    input = 'P';
+    get_next_state(input, &autonomous);
+    assert(*autonomous == boot_val);
+
+    autonomous = &autonomous_val;
+    input = 'w';
+    get_next_state(input, &autonomous);
+    assert(*autonomous == boot_val);
+
+    autonomous = &autonomous_val;
+    input = 'W';
+    get_next_state(input, &autonomous);
+    assert(*autonomous == boot_val);
+
+    // Manual -> Boot transition tests
+    manual = &manual_val;
+    input = 'p';
+    get_next_state(input, &manual);
+    assert(*manual == boot_val);
+
+    manual = &manual_val;
+    input = 'P';
+    get_next_state(input, &manual);
+    assert(*manual == boot_val);
+
+    manual = &manual_val;
+    input = 'w';
+    get_next_state(input, &manual);
+    assert(*manual == boot_val);
+
+    manual = &manual_val;
+    input = 'W';
+    get_next_state(input, &manual);
+    assert(*manual == boot_val);
+}
+
+// Get the next state based on the current state and input
+void get_next_state(char input, State **state)
+{
+    State boot = BOOT;
+    State autonomous = AUTONOMOUS;
+    State manual = MANUAL;
+
+    int curr_state = (int)**state;
+
+    if (curr_state == (int)boot)
+    {
+        if (input == 'P' || input == 'p' || input == 'W' || input == 'w')
+        {
+            *state = &boot;
+        }
+
+        else if (input == 'A' || input == 'a')
+        {
+            *state = &autonomous;
+        }
+
+        else if (input == 'M' || input == 'm')
+        {
+            *state = &manual;
+        }
+    }
+
+    else if (curr_state == (int)autonomous)
+    {
+        if (input == 'P' || input == 'p' || input == 'W' || input == 'w')
+        {
+            *state = &boot;
+        }
+
+        else
+        {
+            *state = &autonomous;
+        }
+    }
+
+    else if (curr_state == (int)manual)
+    {
+        if (input == 'P' || input == 'p' || input == 'W' || input == 'w')
+        {
+            *state = &boot;
+        }
+
+        else
+        {
+            *state = &manual;
+        }
+    }
+
+    else
+    {
+        printf("Error: Unknown State\n");
+    }
+}