From 462515b5667d2c2c78fe2d8068309cdc28d09b7f Mon Sep 17 00:00:00 2001
From: Martin Preuss <martin@aquamaniac.de>
Date: Sat, 22 Apr 2023 12:12:19 +0200
Subject: [PATCH] avr: reduce register use in com2WaitForDataState1ms

---
 avr/modules/com2/lowlevel.asm | 17 ++++++++---------
 1 file changed, 8 insertions(+), 9 deletions(-)

diff --git a/avr/modules/com2/lowlevel.asm b/avr/modules/com2/lowlevel.asm
index f08cc32..406d006 100644
--- a/avr/modules/com2/lowlevel.asm
+++ b/avr/modules/com2/lowlevel.asm
@@ -189,23 +189,22 @@ com2WaitForAttnHigh_done:
 ; ---------------------------------------------------------------------------
 ; com2WaitForDataState1ms
 ;
-; Waits up to COM2_MAXWAIT_US loops for high ATTN line
+; Waits up to 100ms for high DATA line
 ; IN:
+; - R16: state to wait for (00 for low, 0xff for high)
 ; OUT:
 ; - CFLAG: set if state reached, cleared otherwise
-; REGS: R24 (R22)
+; REGS: R17, R22
 
 com2WaitForDataState1ms:
-  ldi r24, 100
+  ldi r17, 100
 com2WaitForDataState1ms_loop:
-    push r17
-      in r17, COM_PIN_DATA
-      eor r17, r16
-      andi r17, (1<<COM_PINNUM_DATA)
-    pop r17
+    in r22, COM_PIN_DATA
+    eor r22, r16
+    andi r22, (1<<COM_PINNUM_DATA)
     breq com2WaitForDataState1ms_stateReached
     Utils_WaitNanoSecs 10000, 0, r22              ; wait for 10us
-    dec r24
+    dec r17
   brne com2WaitForDataState1ms_loop
   clc
   ret