From 0ac1fc7ee84dcd323a47e90a1b9b4ee89d3aaf5f Mon Sep 17 00:00:00 2001
From: Brad Grantham <grantham@plunk.org>
Date: Thu, 31 Dec 2020 11:01:56 -0800
Subject: [PATCH] Add floppy stepper motor state generator

---
 generate_floppy_motor_state.cpp | 125 ++++++++++++++++++++++++++++++++
 1 file changed, 125 insertions(+)
 create mode 100644 generate_floppy_motor_state.cpp

diff --git a/generate_floppy_motor_state.cpp b/generate_floppy_motor_state.cpp
new file mode 100644
index 0000000..059b806
--- /dev/null
+++ b/generate_floppy_motor_state.cpp
@@ -0,0 +1,125 @@
+#include <string>
+#include <array>
+#include <tuple>
+#include <cstdint>
+#include <cstdio>
+
+std::string expandTransitionToString(uint8_t transition)
+{
+    static char reason[512];
+    sprintf(reason, "0x%02X, %d,%d,%d,%d to %d,%d,%d,%d",
+        transition,
+        (transition >> 7) & 1, (transition >> 6) & 1, (transition >> 5) & 1, (transition >> 4) & 1,
+        (transition >> 3) & 1, (transition >> 2) & 1, (transition >> 1) & 1, (transition >> 0) & 1);
+    return reason;
+}
+
+uint8_t motorOnToState(int which)
+{
+    return 1 << (3 - which);
+}
+
+uint8_t makeTransition(uint8_t oldState, uint8_t newState)
+{
+    return (oldState << 4) | newState;
+}
+
+int main()
+{
+    std::array<std::tuple<std::string, std::string>, 256> transitions;
+
+    // initialize to invalid states
+    for(int transition = 0; transition < 256; transition++) {
+        transitions[transition] = {"MOTOR_STATE_NEVER", expandTransitionToString(transition)};
+    }
+
+    for(int turnOn = 0; turnOn < 4; turnOn++) {
+        //step right from aligned to between
+        {
+            int wasOn = (turnOn - 1 + 4) % 4;
+            uint8_t oldState = motorOnToState(wasOn);
+            uint8_t newState = oldState | motorOnToState(turnOn);
+            uint8_t transition = makeTransition(oldState, newState);
+            transitions[transition] = {"MOTOR_RIGHT_ONE", expandTransitionToString(transition)};
+        }
+        //step left from aligned to between
+        {
+            int wasOn = (turnOn + 1) % 4;
+            uint8_t oldState = motorOnToState(wasOn);
+            uint8_t newState = oldState | motorOnToState(turnOn);
+            uint8_t transition = makeTransition(oldState, newState);
+            transitions[transition] = {"MOTOR_LEFT_ONE", expandTransitionToString(transition)};
+        }
+        //step right from aligned to aligned
+        {
+            int wasOn = (turnOn - 1 + 4) % 4;
+            uint8_t oldState = motorOnToState(wasOn);
+            uint8_t newState = motorOnToState(turnOn);
+            uint8_t transition = makeTransition(oldState, newState);
+            transitions[transition] = {"MOTOR_RIGHT_TWO", expandTransitionToString(transition)};
+        }
+        //step left from aligned to aligned
+        {
+            int wasOn = (turnOn + 1) % 4;
+            uint8_t oldState = motorOnToState(wasOn);
+            uint8_t newState = motorOnToState(turnOn);
+            uint8_t transition = makeTransition(oldState, newState);
+            transitions[transition] = {"MOTOR_LEFT_TWO", expandTransitionToString(transition)};
+        }
+        // no magnets energized, energize one
+        {
+            uint8_t oldState = 0;
+            uint8_t newState = motorOnToState(turnOn);
+            uint8_t transition = makeTransition(oldState, newState);
+            transitions[transition] = {"MOTOR_SNAP", expandTransitionToString(transition)};
+        }
+    }
+    for(int turnOff = 0; turnOff < 4; turnOff++) {
+        { //step right from between to aligned
+            int remainsOn = (turnOff + 1) % 4;
+            uint8_t oldState = motorOnToState(remainsOn) | motorOnToState(turnOff);
+            uint8_t newState = motorOnToState(remainsOn);
+            uint8_t transition = makeTransition(oldState, newState);
+            transitions[transition] = {"MOTOR_RIGHT_ONE", expandTransitionToString(transition)};
+        }
+
+        { //step left from between to aligned
+            int remainsOn = (turnOff - 1 + 4) % 4;
+            uint8_t oldState = motorOnToState(remainsOn) | motorOnToState(turnOff);
+            uint8_t newState = motorOnToState(remainsOn);
+            uint8_t transition = makeTransition(oldState, newState);
+            transitions[transition] = {"MOTOR_LEFT_ONE", expandTransitionToString(transition)};
+        }
+
+        { //turn off remaining magnet
+            int wasOn = (turnOff + 1) % 4;
+            uint8_t oldState = motorOnToState(wasOn);
+            uint8_t newState = 0;
+            uint8_t transition = makeTransition(oldState, newState);
+            transitions[transition] = {"MOTOR_NONE", expandTransitionToString(transition)};
+        }
+    }
+
+
+    puts(R"(enum MotorAction
+{
+    MOTOR_RIGHT_ONE,    /* headPosition += 1; */
+    MOTOR_RIGHT_TWO,    /* headPosition += 2; */
+    MOTOR_LEFT_ONE,     /* headPosition -= 1; */
+    MOTOR_LEFT_TWO,     /* headPosition -= 2; */
+    MOTOR_NONE,         /* nothing */
+    MOTOR_SNAP,         /* calculate which way head moves from magnet and head position */
+    MOTOR_STATE_NEVER,  /* should never get this transition */
+};
+
+enum motorActions[256] =
+{)");
+
+
+    for(const auto& [action, reason] : transitions) {
+        printf("    %-18s, // %s\n", action.c_str(), reason.c_str());
+    }
+
+    puts("};");
+}
+