1 files changed, 96 insertions, 0 deletions
diff --git a/fsm/pcint.c b/fsm/pcint.c
new file mode 100644
index 0000000..131d0c3
--- /dev/null
+++ b/fsm/pcint.c
@@ -0,0 +1,96 @@
+// fsm-pcint.c: PCINT (Pin Change Interrupt) functions for SpaghettiMonster.
+// Copyright (C) 2017-2023 Selene ToyKeeper
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+#pragma once
+
+#include <avr/interrupt.h>
+#include <util/delay_basic.h>
+
+uint8_t button_is_pressed() {
+    uint8_t value = ((SWITCH_PORT & (1<<SWITCH_PIN)) == 0);
+    button_last_state = value;
+    return value;
+}
+
+inline void PCINT_on() {
+    #if (ATTINY == 25) || (ATTINY == 45) || (ATTINY == 85)
+        // enable pin change interrupt
+        GIMSK |= (1 << PCIE);
+        // only pay attention to the e-switch pin
+        #if 0  // this is redundant; was already done in main()
+        PCMSK = (1 << SWITCH_PCINT);
+        #endif
+        // set bits 1:0 to 0b01 (interrupt on rising *and* falling edge) (default)
+        // MCUCR &= 0b11111101;  MCUCR |= 0b00000001;
+    #elif (ATTINY == 1634)
+        // enable pin change interrupt
+        #ifdef SWITCH2_PCIE
+        GIMSK |= ((1 << SWITCH_PCIE) | (1 << SWITCH2_PCIE));
+        #else
+        GIMSK |= (1 << SWITCH_PCIE);
+        #endif
+    #elif defined(AVRXMEGA3)  // ATTINY816, 817, etc)
+        SWITCH_ISC_REG |= PORT_ISC_BOTHEDGES_gc;
+    #else
+        #error Unrecognized MCU type
+    #endif
+}
+
+inline void PCINT_off() {
+    #if (ATTINY == 25) || (ATTINY == 45) || (ATTINY == 85)
+        // disable all pin-change interrupts
+        GIMSK &= ~(1 << PCIE);
+    #elif (ATTINY == 1634)
+        // disable all pin-change interrupts
+        GIMSK &= ~(1 << SWITCH_PCIE);
+    #elif defined(AVRXMEGA3)  // ATTINY816, 817, etc)
+        SWITCH_ISC_REG &= ~(PORT_ISC_gm);
+    #else
+        #error Unrecognized MCU type
+    #endif
+}
+
+//void button_change_interrupt() {
+#if (ATTINY == 25) || (ATTINY == 45) || (ATTINY == 85) || (ATTINY == 1634)
+    #ifdef PCINT_vect
+    ISR(PCINT_vect) {
+    #else
+    ISR(PCINT0_vect) {
+    #endif
+#elif defined(AVRXMEGA3)  // ATTINY816, 817, etc)
+    ISR(SWITCH_VECT) {
+        // Write a '1' to clear the interrupt flag
+        SWITCH_INTFLG |= (1 << SWITCH_PIN);
+#else
+    #error Unrecognized MCU type
+#endif
+
+    irq_pcint = 1;  // let deferred code know an interrupt happened
+
+    //DEBUG_FLASH;
+
+    // as it turns out, it's more reliable to detect pin changes from WDT
+    // because PCINT itself tends to double-tap when connected to a
+    // noisy / bouncy switch (so the content of this function has been
+    // moved to a separate function, called from WDT only)
+    // PCINT_inner(button_is_pressed());
+}
+
+// should only be called from PCINT and/or WDT
+// (is a separate function to reduce code duplication)
+void PCINT_inner(uint8_t pressed) {
+    button_last_state = pressed;
+
+    // register the change, and send event to the current state callback
+    if (pressed) {  // user pressed button
+        push_event(B_PRESS);
+        emit_current_event(0);
+    } else {  // user released button
+        // how long was the button held?
+        push_event(B_RELEASE);
+        emit_current_event(ticks_since_last_event);
+    }
+    ticks_since_last_event = 0;
+}
+