WIP:Reduce amount of RAM statically allocated by CommandHandler

CommandHandler.cpp

@@ -183,6 +183,13 @@ void CommandHandler::processChar(char inChar) {
 
           // Execute the stored handler function for the command
           (*commandList[i].function)();
+
+          #ifdef COMMANDHANDLER_DEBUG
+            int free_mem = (int) AVR_STACK_POINTER_REG - (int) __brkval;
+            Serial.print("Free SRAM: ");
+            Serial.println(free_mem);
+          #endif
+
           matched = true;
           break;
         }
@@ -204,8 +211,25 @@ void CommandHandler::processChar(char inChar) {
             Serial.println(command);
           #endif
 
+          // Get remaining part of the command buffer
+          // Max length minus command (at least 1 byte)
+          // And delimiter (at least 1 byte)
+          char remaining[COMMANDHANDLER_BUFFER-2];
+          strcpy(remaining, last);
+          // Terminate it with terminator and null byte
+          char eol[2] = {term, STRING_NULL_TERM};
+          strcat(remaining, eol);
+          // Clear buffer so that relay command can use it if needed
+          clearBuffer();
           // Execute the stored handler function for the command
-          (*relayList[i].function)(remaining(), relayList[i].pt2Object);
+          (*relayList[i].function)(remaining, relayList[i].pt2Object);
+
+          #ifdef COMMANDHANDLER_DEBUG
+            int free_mem = (int) AVR_STACK_POINTER_REG - (int) __brkval;
+            Serial.print("Free SRAM: ");
+            Serial.print(free_mem);
+            Serial.println(term);
+
           matched = true;
           break;
         }
@@ -225,6 +249,10 @@ void CommandHandler::processChar(char inChar) {
       buffer[bufPos] = inChar;  // Put character into buffer
       buffer[bufPos+1] = STRING_NULL_TERM;      // Null terminate
       bufPos++;
+      #ifdef COMMANDHANDLER_DEBUG
+      Serial.print("Current buffer: ");
+      Serial.println(buffer);
+      #endif
     } else {
       #ifdef COMMANDHANDLER_DEBUG
         Serial.println("Line buffer is full - increase COMMANDHANDLER_BUFFER");
@@ -249,37 +277,6 @@ char *CommandHandler::next() {
   return strtok_r(NULL, delim, &last);
 }
 
-/**
- * Returns char* of the remaining of the command buffer (for getting arguments to commands).
- * Returns NULL if no more tokens exist.
- */
-char *CommandHandler::remaining() {
-
-  //reinit the remains char
-  remains[0] = STRING_NULL_TERM;
-
-  char str_term[2];
-  str_term[0] = term;
-  str_term[1] = STRING_NULL_TERM;
-
-   // Search for the remaining up to next term
-  char *command = strtok_r(NULL, str_term, &last);
-
-  // forge term in string format
-  strcpy(remains, command);
-  strcat(remains, str_term);
-
-  // clear the buffer now, we emptied the current command
-  // the remaining is might be given to another handler
-  // or it might used by the same commandHandler instance
-  // hence the buffer should be emptied now
-  clearBuffer();
-
-  return remains;
-}
-
-
-
 /*****************************************
  * Helpers to read args and cast them into specific type, strongly inspired by CmdMessenger
  *****************************************/
@@ -502,8 +499,8 @@ void CommandHandler::addCmdString(const char *value) {
 
 char* CommandHandler::getOutCmd() {
 
+  char command[COMMANDHANDLER_BUFFER + 1];
   commandString.toCharArray(command, COMMANDHANDLER_BUFFER + 1);
-
   return command;
 }
 
@@ -517,4 +514,6 @@ void CommandHandler::sendCmdSerial() {
 
 void CommandHandler::sendCmdSerial(Stream &outStream) {
   outStream.print(commandString);
+  // FIXME string not set to null, potential memory leak here
+  // if string construction is not started from initCmd()
 }

CommandHandler.h

@@ -46,7 +46,11 @@
 #define STRING_NULL_TERM '\0'
 
 // Uncomment the next line to run the library in debug mode (verbose messages)
-// #define COMMANDHANDLER_DEBUG
+//#define COMMANDHANDLER_DEBUG
+
+#ifdef COMMANDHANDLER_DEBUG
+extern void *__brkval;
+#endif
 
 
 class CommandHandler {
@@ -133,9 +137,6 @@ class CommandHandler {
     byte bufPos;                        // Current position in the buffer
     char *last;                         // State variable used by strtok_r during processing
 
-    char remains[COMMANDHANDLER_BUFFER + 1]; // Buffer of stored characters to pass to a relay function
-
-    char command[COMMANDHANDLER_BUFFER + 1];
     String commandString; // Out Command
     String commandHeader; // header for out command
     byte commandDecimal;

examples/Demo/Demo.ino

@@ -18,8 +18,8 @@ void setup() {
 
   // Setup callbacks for SerialCommand commands
   cmdHdl.addCommand("HELLO", sayHello);        // Echos the string argument back
-  cmdHdl.addCommand("FWD",   forwardRemaining);// Fwd the remaining of the command to the cmdHdl
-  cmdHdl.addCommand("P",     processCommand);  // Converts two arguments, first to double and echos them back
+  cmdHdl.addCommand("P", processCommand);      // Converts two arguments, first to double and echos them back
+  cmdHdl.addRelay("FWD", fwdRelay);            // An example of relay function that gets the whole substring as an arguments
   cmdHdl.addCommand("GUESS", guessMyName);     // A game for guessing my name, used to test compareStringArg
   cmdHdl.addCommand("PING", pongMesssage);     // A function that use the packet forging tool to send a random ping time
   cmdHdl.setDefaultHandler(unrecognized);      // Handler for command that isn't matched  (says "What?")
@@ -86,12 +86,7 @@ void loop() {
   // Imagine your main program receiving "M1,P,2000;" command throught Serial
   // The main program could redirect the "P,2000;" string command to the a device called "M1"
   // The M1 device can then use its own commandHandler to handle the sub command "P,2000;"
-  // To extract the remaining of a command, you can use the function remaining()
-  // This is illustrated in the forwardRemaining() function
-  // that is associated to the FWD command in this example
-  // Send "FWD,P,2000;" to the board, it should forward the "P,2000;" to itself
-  // (thanks to the processString() function)
-  // As "P" is assocviated with the processCommand() function, it will run it
+  // This is achieved by the use of relay functions (see example below)
 
   // Below are a bunch of serial command you can try sending
   // Try predicting what it will do
@@ -114,16 +109,12 @@ void sayHello() {
   }
 }
 
-void forwardRemaining() {
-  char *remaining;
-  remaining = cmdHdl.remaining();    // Get the next argument from the SerialCommand object buffer
-  if (remaining != NULL) {    // As long as it existed, take it
-    Serial.print("Forwarding ");
-    Serial.println(remaining);
-    cmdHdl.processString(remaining);
-  } else {
-    Serial.print("Nothing to forward");
-  }
+void fwdRelay(char* remaining){
+  Serial.print("Relay function, got substring - ");
+  Serial.println(remaining);
+  // Here we can do whatever we want with the remaining substring.
+  // For example, we can extract another command and process it:
+  cmdHdl.processString(remaining);
 }
 
 void processCommand() {