avr: added routine CPRO_ReadValue

avr/modules/comproto/msg_value.asm

@@ -16,6 +16,35 @@
 .cseg
 
 
+
+; ---------------------------------------------------------------------------
+; @routine CPRO_ReadValue @global
+; Read a REPORT_VALUE/SET_VALUE message.
+;
+; @param  X       buffer to read from
+; @return R17     value id
+; @return R19:R18 value
+; @return R21:R20 denom (e.g. 100, meaning value must be divided by 100)
+; @return R22     source address
+; @return R23     command
+
+CPRO_ReadValue:
+  adiw xh:xl, 2
+  ld r23, X+    ; command
+  ld r22, X+    ; src address
+  adiw xh:xl, 6 ; skip uid, msg id
+  ld r17, X
+  adiw xh:xl, 2 ; skip value id, value type
+  ld r18, X+
+  ld r19, X+
+  ld r20, X+
+  ld r21, X+
+  sbiw xh:xl, 16                                        ; back to msg begin
+  ret
+; @end
+
+
+
 ; ---------------------------------------------------------------------------
 ; @routine CPRO_WriteReportValue @global
 ; Write a REPORT_VALUE packet.