1 files changed, 25 insertions, 3 deletions
diff --git a/src/peripherals/avrdx-slpctrl.ts b/src/peripherals/avrdx-slpctrl.ts
index 1e75c12..307810e 100644
--- a/src/peripherals/avrdx-slpctrl.ts
+++ b/src/peripherals/avrdx-slpctrl.ts
@@ -1,14 +1,23 @@
 // AVR-Dx SLPCTRL - Sleep Controller
-// Handles the SLEEP instruction by fast-forwarding to the next clock event.
 
 import type { CPU } from 'avr8js/cpu/cpu';
 
 const CTRLA = 0;
 const SEN_bm    = 0x01;
-// const SMODE_gm  = 0x06;
+const SMODE_gm  = 0x06;
+
+export const SMODE_IDLE_gc = 0x00;
+export const SMODE_STDBY_gc = 0x02;
+export const SMODE_PDOWN_gc = 0x04;
+
+
+export type SMODE = typeof SMODE_IDLE_gc | typeof SMODE_STDBY_gc | typeof SMODE_PDOWN_gc;
+export type SleepCallback = (mode: SMODE) => void;
 
 export class AVRDxSLPCTRL {
   sleepUntil: number = 0;
+  sleeping: null | SMODE = null;
+  callbacks: SleepCallback[];
   
   constructor(private cpu: CPU, private base: number) {
     // CTRLA - sleep mode + sleep enable
@@ -21,15 +30,28 @@ export class AVRDxSLPCTRL {
     cpu.onSleep = () => {
       this.handleSleep();
     };
+
+    this.callbacks = [];
   }
 
   private handleSleep() {
     const ctrla = this.cpu.data[this.base + CTRLA];
-    if (!(ctrla & SEN_bm)) return; // sleep not enabled
+    if (!(ctrla & SEN_bm)) return;
+
+    const mode = ctrla & SMODE_gm;
+    this.sleeping = mode as SMODE;
 
     const nextEvent = (this.cpu as any).nextClockEvent;
     if (nextEvent) {
       this.sleepUntil = nextEvent.cycles;
     }
+
+    for (const cb of this.callbacks) {
+      cb(mode as SMODE);
+    }
+  }
+
+  onSleep(cb: SleepCallback) {
+    this.callbacks.push(cb);
   }
 }