From ab72a75d8fe4ac3859655ede97de2f25973a8864 Mon Sep 17 00:00:00 2001
From: Asbelos <asbelos@btinternet.com>
Date: Fri, 19 Jul 2024 08:33:50 +0100
Subject: [PATCH] EXRAIL MOMENTUM

---
 DCC.cpp             | 16 ++++++++++------
 DCCEXParser.cpp     |  3 ++-
 EXRAIL2.cpp         |  4 ++++
 EXRAIL2.h           |  1 +
 EXRAIL2MacroReset.h |  2 ++
 EXRAILMacros.h      |  1 +
 6 files changed, 20 insertions(+), 7 deletions(-)

diff --git a/DCC.cpp b/DCC.cpp
index 5b387b2..71f36de 100644
--- a/DCC.cpp
+++ b/DCC.cpp
@@ -914,13 +914,17 @@ int DCC::lookupSpeedTable(int locoId, bool autoCreate) {
 }
 
 bool DCC::setMomentum(int locoId,int16_t millis_per_notch) {
-  if (locoId<0 || millis_per_notch<0) return false;
-  if (locoId==0) defaultMomentum=millis_per_notch;
-  else {
-    auto reg=lookupSpeedTable(locoId);
-    if (reg<0) return false;
-    speedTable[reg].millis_per_notch=millis_per_notch;
+  if (locoId==0 && millis_per_notch>=0) {
+    defaultMomentum=millis_per_notch;
+    return true;
   }
+  // millis=-1 is ok and means this loco should use the default.
+  // We dont copy the default here because it can be changed 
+  // while running and have immediate effect on all locos using -1.
+  if (locoId<=0 || millis_per_notch<-1) return false;
+  auto reg=lookupSpeedTable(locoId);
+  if (reg<0) return false; // table full
+  speedTable[reg].millis_per_notch=millis_per_notch;
   return true; 
 }
  
diff --git a/DCCEXParser.cpp b/DCCEXParser.cpp
index 471ad05..0e45072 100644
--- a/DCCEXParser.cpp
+++ b/DCCEXParser.cpp
@@ -68,7 +68,8 @@ Once a new OPCODE is decided upon, update this list.
   K, Reserved for future use - Potentially Railcom
   l, Loco speedbyte/function map broadcast
   L, Reserved for LCC interface (implemented in EXRAIL)
-  m, message to throttles broadcast 
+  m, message to throttles (broadcast output) 
+  m, set momentum  
   M, Write DCC packet
   n, Reserved for SensorCam
   N, Reserved for Sensorcam 
diff --git a/EXRAIL2.cpp b/EXRAIL2.cpp
index 1a7f888..d65aca4 100644
--- a/EXRAIL2.cpp
+++ b/EXRAIL2.cpp
@@ -566,6 +566,10 @@ void RMFT2::loop2() {
     forward=DCC::getThrottleDirection(loco)^invert;
     driveLoco(operand);
     break;
+  
+  case OPCODE_MOMENTUM:
+    DCC::setMomentum(loco,operand);
+    break;
     
   case OPCODE_FORGET:
     if (loco!=0) {
diff --git a/EXRAIL2.h b/EXRAIL2.h
index 9271bba..b0ed324 100644
--- a/EXRAIL2.h
+++ b/EXRAIL2.h
@@ -35,6 +35,7 @@
 // 
 enum OPCODE : byte {OPCODE_THROW,OPCODE_CLOSE,OPCODE_TOGGLE_TURNOUT,
              OPCODE_FWD,OPCODE_REV,OPCODE_SPEED,OPCODE_INVERT_DIRECTION,
+             OPCODE_MOMENTUM,
              OPCODE_RESERVE,OPCODE_FREE,
              OPCODE_AT,OPCODE_AFTER,
              OPCODE_AFTEROVERLOAD,OPCODE_AUTOSTART,
diff --git a/EXRAIL2MacroReset.h b/EXRAIL2MacroReset.h
index 8f2845c..8773787 100644
--- a/EXRAIL2MacroReset.h
+++ b/EXRAIL2MacroReset.h
@@ -98,6 +98,7 @@
 #undef LCC 
 #undef LCCX 
 #undef LCN 
+#undef MOMENTUM
 #undef MOVETT
 #undef ACON
 #undef ACOF
@@ -265,6 +266,7 @@
 #define LCC(eventid) 
 #define LCCX(senderid,eventid) 
 #define LCD(row,msg)
+#define MOMENTUM(mspertick)
 #define SCREEN(display,row,msg)
 #define LCN(msg) 
 #define MESSAGE(msg)
diff --git a/EXRAILMacros.h b/EXRAILMacros.h
index edc1088..4f7d41a 100644
--- a/EXRAILMacros.h
+++ b/EXRAILMacros.h
@@ -551,6 +551,7 @@ int RMFT2::onLCCLookup[RMFT2::countLCCLookup];
 #define STEALTH_GLOBAL(code...) 
 #define LCN(msg) PRINT(msg)
 #define MESSAGE(msg) PRINT(msg)
+#define MOMENTUM(mspertick) OPCODE_MOMENTUM,V(mspertick),
 #define MOVETT(id,steps,activity) OPCODE_SERVO,V(id),OPCODE_PAD,V(steps),OPCODE_PAD,V(EXTurntable::activity),OPCODE_PAD,V(0),
 #define ONACTIVATE(addr,subaddr) OPCODE_ONACTIVATE,V(addr<<2|subaddr),
 #define ONACTIVATEL(linear) OPCODE_ONACTIVATE,V(linear+3),