From ca6f9bb91893cf50c8e09bf7396085a7d69e80ab Mon Sep 17 00:00:00 2001
From: gbc dev <gbc@localhost>
Date: Thu, 16 Jul 2026 12:49:02 +0200
Subject: headless: $ED opcode = clean power-off (exit + battery save)

The unused SM83 opcode $ED now sets gb->poweroff, which breaks the headless
loop so the normal cart_free()->cart_save() path runs. Lets a guest OS shut the
emulator down cleanly (and flush its .sav) instead of relying on an external
timeout/SIGTERM, which could SIGKILL before the save. run_frame() also stops on
poweroff so exit is immediate.
---
 src/cpu.c | 2 ++
 1 file changed, 2 insertions(+)

(limited to 'src/cpu.c')

diff --git a/src/cpu.c b/src/cpu.c
index 9e7f685..5b73724 100644
--- a/src/cpu.c
+++ b/src/cpu.c
@@ -407,6 +407,8 @@ int cpu_step(GB *gb) {
 
     case 0xCB: do_cb(gb); break;
 
+    case 0xED: gb->poweroff = true; break;  // (illegal on HW) clean-exit signal
+
     default:
         // 0x40-0xBF block: LD r,r' and ALU A,r
         if (op >= 0x40 && op < 0x80) {
-- 
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