From ae4058add3c2002b90f171a1ace40bf21118103e Mon Sep 17 00:00:00 2001
From: "Kartik K. Agaram" <vc@akkartik.com>
Date: Thu, 7 Dec 2023 21:48:47 -0800
Subject: halt until exception when waiting for keyboard

This reduces CPU consumption from 180% to 2% when running Qemu.

Many thanks to Fabian of https://copy.sh for this suggestion.
---
 102keyboard.subx | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/102keyboard.subx b/102keyboard.subx
index 39788075..f963baa2 100644
--- a/102keyboard.subx
+++ b/102keyboard.subx
@@ -24,6 +24,8 @@ read-key:  # kbd: (addr keyboard) -> result/eax: byte
     89/<- %ebp 4/r32/esp
     # . save registers
     51/push-ecx
+    # wait for an interrupt to save power on Qemu
+    f4/hlt
     # result = 0
     b8/copy-to-eax 0/imm32
     # ecx = keyboard
-- 
cgit 1.4.1-2-gfad0