avr: reorganized common code.

avr/common/inccounter16.asm

@@ -0,0 +1,47 @@
+; ***************************************************************************
+; copyright   : (C) 2026 by Martin Preuss
+; email       : martin@libchipcard.de
+;
+; ***************************************************************************
+; * This file is part of the project "AqHome".                              *
+; * Please see toplevel file COPYING of that project for license details.   *
+; ***************************************************************************
+
+#ifndef AQH_AVR_COMMON_INCCOUNTER16_ASM
+#define AQH_AVR_COMMON_INCCOUNTER16_ASM
+
+
+
+; ***************************************************************************
+; code
+
+
+.cseg
+
+
+
+; ---------------------------------------------------------------------------
+; @routine Utils_IncrementCounter16 @global
+;
+; Increment a 16 bit counter at the address given by X.
+;
+; @param X Address of the 2 byte counter (1. byte is LSB)
+; @clobbers r18, r19, r22
+
+Utils_IncrementCounter16:
+  ld r18, x+
+  ld r19, x
+  ldi r22, 1
+  add r18, r22
+  clr r22       ; doesn't affect carry flag
+  adc r19, r22
+  st x, r19
+  st -x, r18
+  ret
+; @end
+
+
+
+
+#endif
+