Diff: linkLayerEncoder/linkLayer.cpp

Revision:

2:bf699e054b34

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/linkLayerEncoder/linkLayer.cpp	Sun Feb 25 16:40:28 2018 +0000
@@ -0,0 +1,96 @@
+#include "linkLayer.h"
+#include "global.h"
+
+void LinkLayerEncoder::setPacket(linkPacket* p)
+{
+    encoderIndex = 0;
+    lp = p;
+    oneCntr = 0;
+    hasPacket = 1;
+    preambleBits=8;
+    frameTypeBits=8;
+}
+bool LinkLayerEncoder::getNext()
+{
+    if(!hasPacket)//no active packet to send, get next
+        setPacket(txQueue.getNext());//rtos semaphore; wait until new data available
+    if(preambleBits-->0)//send preamble
+    {
+        return preambleBits<7;//send 1111 1110
+    }
+    if(frameTypeBits-->0)//send frametype
+    {
+        unsigned bitIndex = 7-frameTypeBits;
+        
+        bool real = (bool)(lp->frameType&(1<<bitIndex));
+        bool returnVal;
+        if(real)
+        {
+            if((oneCntr ++)<6)
+                        returnVal=1;
+            else
+            {   
+                returnVal=0; // insert stuffing zero
+                frameTypeBits++;//need to transmit one bit next 
+                oneCntr=0;
+            }
+        }
+        else
+        {
+            if(oneCntr==6)
+            {
+                returnVal=0; // insert stuffing zero
+                frameTypeBits++;//need to transmit one bit next 
+                oneCntr=0;
+            }
+            else
+            {
+                oneCntr=0;
+                returnVal=0;
+            }
+        }
+        return returnVal;
+    }
+    unsigned byteIndex = encoderIndex / 8;
+    unsigned bitIndex = encoderIndex % 8;
+    encoderIndex++;
+    
+    bool real = (bool)(lp->payload[byteIndex]&(1<<bitIndex));
+    bool returnVal;
+    if(real)
+    {
+        if((oneCntr ++)<6)
+                    returnVal=1;
+        else
+        {   
+            returnVal=0; // insert stuffing zero
+            encoderIndex--;//need to transmit one bit next 
+            oneCntr=0;
+        }
+    }
+    else
+    {
+        if(oneCntr==6)
+        {
+            returnVal=0; // insert stuffing zero
+            encoderIndex--;//need to transmit one bit next 
+            oneCntr=0;
+        }
+        else
+        {
+            oneCntr=0;
+            returnVal=0;
+        }
+    }
+    
+    
+    byteIndex = encoderIndex / 8;
+    if(byteIndex >= lp->payloadSz)
+    {
+        hasPacket=0;
+        delete lp->payload;
+        delete lp;
+    }
+
+    return returnVal;
+}
\ No newline at end of file