1 files changed, 105 insertions, 0 deletions
diff --git a/fsm/states.c b/fsm/states.c
new file mode 100644
index 0000000..4b94ce9
--- /dev/null
+++ b/fsm/states.c
@@ -0,0 +1,105 @@
+// fsm-states.c: State-handling functions for SpaghettiMonster.
+// Copyright (C) 2017-2023 Selene ToyKeeper
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+#pragma once
+
+#include "fsm-states.h"
+#include "fsm-adc.h"
+
+// TODO: if callback doesn't handle current event,
+//       pass event to next state on stack?
+//       Callback return values:
+//       0: event handled normally
+//       1: event not handled
+//       255: error (not sure what this would even mean though, or what difference it would make)
+// TODO: function to call stacked callbacks until one returns "handled"
+
+void _set_state(StatePtr new_state, uint16_t arg,
+                Event exit_event, Event enter_event) {
+    // call old state-exit hook (don't use stack)
+    if (current_state != NULL) current_state(exit_event, arg);
+    // set new state
+    current_state = new_state;
+    // call new state-enter hook (don't use stack)
+    if (new_state != NULL) current_state(enter_event, arg);
+
+    // since state changed, stop any animation in progress
+    interrupt_nice_delays();
+}
+
+int8_t push_state(StatePtr new_state, uint16_t arg) {
+    if (state_stack_len < STATE_STACK_SIZE) {
+        // TODO: call old state's exit hook?
+        //       new hook for non-exit recursion into child?
+        state_stack[state_stack_len] = new_state;
+        state_stack_len ++;
+        // FIXME: use EV_stacked_state?
+        _set_state(new_state, arg, EV_leave_state, EV_enter_state);
+        return state_stack_len;
+    } else {
+        // TODO: um...  how is a flashlight supposed to handle a recursion depth error?
+        return -1;
+    }
+}
+
+StatePtr pop_state() {
+    // TODO: how to handle pop from empty stack?
+    StatePtr old_state = NULL;
+    StatePtr new_state = NULL;
+    if (state_stack_len > 0) {
+        state_stack_len --;
+        old_state = state_stack[state_stack_len];
+    }
+    if (state_stack_len > 0) {
+        new_state = state_stack[state_stack_len-1];
+    }
+    // FIXME: what should 'arg' be?  (maybe re-entry should be entry with arg+1?)
+    _set_state(new_state, 0, EV_leave_state, EV_reenter_state);
+    return old_state;
+}
+
+uint8_t set_state(StatePtr new_state, uint16_t arg) {
+    // FIXME: this calls exit/enter hooks it shouldn't
+    //        (for the layer underneath the top)
+    pop_state();
+    return push_state(new_state, arg);
+}
+
+void set_state_deferred(StatePtr new_state, uint16_t arg) {
+    deferred_state = new_state;
+    deferred_state_arg = arg;
+}
+
+#ifndef DONT_USE_DEFAULT_STATE
+// bottom state on stack
+// handles default actions for LVP, thermal regulation, etc
+uint8_t default_state(Event event, uint16_t arg) {
+    if (0) {}  // this should get compiled out
+
+    #ifdef USE_LVP
+    else if (event == EV_voltage_low) {
+        low_voltage();
+        return EVENT_HANDLED;
+    }
+    #endif
+
+    #if 0
+    #ifdef USE_THERMAL_REGULATION
+    else if (event == EV_temperature_high) {
+        high_temperature();
+        return 0;
+    }
+
+    else if (event == EV_temperature_low) {
+        low_temperature();
+        return 0;
+    }
+    #endif
+    #endif
+
+    // event not handled
+    return EVENT_NOT_HANDLED;
+}
+#endif
+