improve both ecx_statecheck and ecx_readstate

- in ecx_statecheck only one iteration is done through the slave list if needed
- in ecx_readstate only one datagram is used if possible

soem/ethercatmain.c

@@ -756,12 +756,62 @@ int ecx_FPRD_multi(ecx_contextt *context, int n, uint16 *configlst, ec_alstatust
  */
 int ecx_readstate(ecx_contextt *context)
 {
-   uint16 slave, fslave, lslave, configadr, lowest, rval;
+   uint16 slave, fslave, lslave, configadr, lowest, rval, bitwisestate;
    ec_alstatust sl[MAX_FPRD_MULTI];
    uint16 slca[MAX_FPRD_MULTI];
+   boolean noerrorflag, allslavessamestate;
 
-   lowest = 0xff;
+   /* Try to establish the state of all slaves sending only one broadcast datargam.
+    * This way a number of datagrams equal to the number of slaves will be sent only if needed.*/
+   rval = 0;
+   ecx_BRD(context->port, 0, ECT_REG_ALSTAT, sizeof(rval), &rval, EC_TIMEOUTRET);
+   rval = etohs(rval);
+   bitwisestate = (rval & 0x0f);
+
+   if ((rval & EC_STATE_ERROR) == 0)
+   {
+      noerrorflag = TRUE;
       context->slavelist[0].ALstatuscode = 0;
+   }   
+   else
+   {
+      noerrorflag = FALSE;
+   }
+
+   switch (bitwisestate)
+   {
+      case EC_STATE_INIT:
+      case EC_STATE_PRE_OP:
+      case EC_STATE_BOOT:
+      case EC_STATE_SAFE_OP:
+      case EC_STATE_OPERATIONAL:
+         allslavessamestate = TRUE;
+         context->slavelist[0].state = bitwisestate;
+         break;
+      default:
+         allslavessamestate = FALSE;
+         break;
+   }
+    
+   if (noerrorflag && allslavessamestate)
+   {
+      /* No slave has toggled the error flag so the alstatuscode
+       * (even if different from 0) should be ignored and
+       * the slaves have reached the same state so the internal state
+       * can be updated without sending any datagram. */
+      for (slave = 1; slave <= *(context->slavecount); slave++)
+      {
+         context->slavelist[slave].ALstatuscode = 0x0000;
+         context->slavelist[slave].state = bitwisestate;
+      }
+      lowest = bitwisestate;
+   }
+   else
+   {
+      /* Not all slaves have the same state or at least one is in error so one datagram per slave
+       * is needed. */
+      context->slavelist[0].ALstatuscode = 0;
+      lowest = 0xff;
       fslave = 1;
       do
       {
@@ -772,7 +822,7 @@ int ecx_readstate(ecx_contextt *context)
          }
          for (slave = fslave; slave <= lslave; slave++)
          {
-         const ec_alstatust zero = {0, 0, 0};
+            const ec_alstatust zero = { 0, 0, 0 };
 
             configadr = context->slavelist[slave].configadr;
             slca[slave - fslave] = configadr;
@@ -792,8 +842,9 @@ int ecx_readstate(ecx_contextt *context)
             context->slavelist[0].ALstatuscode |= context->slavelist[slave].ALstatuscode;
          }
          fslave = lslave + 1;
-   } while(lslave < *(context->slavecount));
+      } while (lslave < *(context->slavecount));
       context->slavelist[0].state = lowest;
+   }
   
    return lowest;
 }
@@ -851,36 +902,70 @@ uint16 ecx_statecheck(ecx_contextt *context, uint16 slave, uint16 reqstate, int
       {
          uint16 bitwisestate;
          uint16 slaveindex;
+         boolean allslavessamestate;
+         boolean noerrorflag;
     
          rval = 0;
          ecx_BRD(context->port, 0, ECT_REG_ALSTAT, sizeof(rval), &rval , EC_TIMEOUTRET);
          rval = etohs(rval);
          bitwisestate = (rval & 0x0f);
 
-         if((rval & 0xf0) == 0)
+         if ((rval & EC_STATE_ERROR) == 0)
          {
-            /* No slave has toggled the error flag so the alstatuscode (even if different from 0) should be ignored */
+            noerrorflag = TRUE;
-            for(slaveindex = 1; slaveindex <= *(context->slavecount); slaveindex++)
+            context->slavelist[0].ALstatuscode = 0;
-            {
-               context->slavelist[slaveindex].ALstatuscode = 0x0000;
          }   
+         else
+         {
+            noerrorflag = FALSE;
          }
 
-         switch(bitwisestate)
+         switch (bitwisestate)
          {
             case EC_STATE_INIT:
             case EC_STATE_PRE_OP:
             case EC_STATE_BOOT:
             case EC_STATE_SAFE_OP:
             case EC_STATE_OPERATIONAL:
-               /* All the slaves have reached the same state so we can update the state of every slave */
+               allslavessamestate = TRUE;
-               for(slaveindex = 1; slaveindex <= *(context->slavecount); slaveindex++)
+               break;
+            default:
+               allslavessamestate = FALSE;
+               break;
+         }
+
+         if (noerrorflag || allslavessamestate)
+         {
+             if (noerrorflag && allslavessamestate)
+             {
+                /* No slave has toggled the error flag so the alstatuscode
+                 * (even if different from 0) should be ignored and 
+                 * the slaves have reached the same state so the internal state
+                 * can be updated without sending any datagram. */
+                for (slaveindex = 1; slaveindex <= *(context->slavecount); slaveindex++)
+                {
+                   context->slavelist[slaveindex].ALstatuscode = 0x0000;
+                   context->slavelist[slaveindex].state = bitwisestate;
+                 }
+             }
+             else if (noerrorflag)
+             {
+                /* No slave has toggled the error flag so the alstatuscode
+                 * (even if different from 0) should be ignored. */
+                for (slaveindex = 1; slaveindex <= *(context->slavecount); slaveindex++)
+                {
+                   context->slavelist[slaveindex].ALstatuscode = 0x0000;
+                }
+             }
+             else
+             {
+                /* All the slaves have reached the same state therefore
+                 * the internal state can be updated without sending any datagram. */  
+                for (slaveindex = 1; slaveindex <= *(context->slavecount); slaveindex++)
                 {
                    context->slavelist[slaveindex].state = bitwisestate;
                 }
-               break;
+             }
-            default:
-               break;
          }   
       }
       else