avr: add code to prepare a RESULT message.

avr/modules/comproto/msg_result.asm

@@ -0,0 +1,47 @@
+; ***************************************************************************
+; copyright   : (C) 2024 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.   *
+; ***************************************************************************
+
+
+
+
+; ***************************************************************************
+; code
+
+.cseg
+
+
+; ---------------------------------------------------------------------------
+; @routine CPRO_WriteResult @global
+; Write a RESULT message.
+;
+; @return nothing
+; @param  R16     destination address
+; @param  R17     result
+; @param  R19:R18 ref msg id
+; @param  X       buffer to write to
+; @clobbers       R16 (R17, R18, R19, R20, R21)
+
+CPRO_WriteResult:
+  st X+, r16     ; dest address
+  ldi r16, 5     ; msg code+src address+3 payload bytes
+  st X+, r16     ; msg len
+  ldi r16, CPRO_CMD_RESULT
+  st X+, r16     ; msg code
+  lds r16, com2Address
+  st X+, r16     ; src address
+  st X+, r18     ; ref msg id (low)
+  st X+, r19     ; ref msg id (high)
+  st X+, r17     ; result
+  sbiw xh:xl, 7  ; go back to beginning of message
+
+  ; calc and add checksum
+  rcall com2CalcAndAddChecksumByte           ; (R16, R17, R18, R19, X)
+  sbiw xh:xl, 8                              ; go back to beginning of message
+  ret
+; @end