Diff: swtp_codec.cpp

Revision:

1:c189b357fc3c

Parent:

0:b61d45ff9b8e

Child:

2:4dd0a9382f0d

--- a/swtp_codec.cpp	Tue Aug 30 10:30:50 2011 +0000
+++ b/swtp_codec.cpp	Tue Aug 30 17:45:12 2011 +0000
@@ -1,8 +1,80 @@
 #include "mbed.h"
+#include <string.h>
+#include <stdlib.h>
 #include "swtp_codec.h"
 
+////////////////////////////////////
+// First byte for INFO packets...
+
+//  Hdr Ctl  |--- Version --|
+//   X   X   X  X  X  X  X  X
+
+#define CONTROL_PKT_IND_BIT (1<<6)
+#define HEADER_PKT_IND_BIT  (1<<7)
+
+#define VERSION_MASK         (0x3F) // 00111111
+#define CONTROL_PKT_IND_MASK (0xBF) // 10111111
+#define HEADER_PKT_IND_MASK  (0x7F) // 01111111
+////////////////////////////////////
+
 extern Serial pc;
 
-void encodeHeaderPacket(char* packetToFill, int mimeType, int payloadLengthBytes, int startPayloadSequenceNumber) {
-    pc.puts("Encoding header\n\r");
+/**
+ * Encodes a given HeaderPacket data structure into byte buffer suitable for transmission.
+ * @param packetToFill Byte array to be encoded into.
+ * @param packetSize Size of byte buffer
+ * @param headerData Structure giving the data that is to be packed.
+ */
+void encodeHeaderPacket(unsigned char* packetToFill, int packetSize, PacketData* headerData) {
+
+    for (int i = 0; i < packetSize; i++) packetToFill[i] = 0;
+
+    // Control Byte
+    packetToFill[0] =  (SWTP_VERSION & VERSION_MASK); // bits 0:5
+    packetToFill[0] |= (CONTROL_PKT_IND_MASK);        // bit 6 = 0
+    packetToFill[0] &= (HEADER_PKT_IND_BIT);          // bit 7 = 1
+
+    // Mime Type
+    packetToFill[1] = (headerData->messageHeader.mimeType & 0x00FF);
+    packetToFill[2] = (headerData->messageHeader.mimeType & 0xFF00) >> 8;
+
+    // Content length
+    packetToFill[3] = (headerData->messageHeader.payloadLengthBytes >>  0) & 0xFF;
+    packetToFill[4] = (headerData->messageHeader.payloadLengthBytes >>  8) & 0xFF;
+    packetToFill[5] = (headerData->messageHeader.payloadLengthBytes >> 16) & 0xFF;
+    packetToFill[6] = (headerData->messageHeader.payloadLengthBytes >> 24) & 0xFF;
+
+    // First payload sequence number
+    packetToFill[7] = (headerData->messageHeader.startPayloadSequenceNumber & 0x00FF);
+    packetToFill[8] = (headerData->messageHeader.startPayloadSequenceNumber & 0xFF00) >> 8;
+
 }
+
+/**
+ * Decodes a byte array of data into a HeaderPacket.
+ * @param packet Byte array to decode from.
+ * @param packetSize Number of bytes in array
+ * @param headerDataToFill Structure of PacketData to populate
+ */
+void decodeHeaderPacket(uint8* packet, int packetSize, PacketData* headerDataToFill) {
+
+    headerDataToFill->version         = (packet[0] & VERSION_MASK);
+    headerDataToFill->isMessageHeader = (packet[0] & HEADER_PKT_IND_BIT);
+    headerDataToFill->isControlPacket = (packet[0] & CONTROL_PKT_IND_BIT);
+
+    if (headerDataToFill->isMessageHeader) {
+        headerDataToFill->messageHeader.mimeType = (packet[2] << 8) | packet[1];
+        headerDataToFill->messageHeader.payloadLengthBytes =
+            (packet[3] <<  0) |
+            (packet[4] <<  8) |
+            (packet[5] << 16) |
+            (packet[6] << 24)
+        ;
+        headerDataToFill->messageHeader.startPayloadSequenceNumber = (packet[8] << 8) | packet[7];
+    } else if (headerDataToFill->isControlPacket) {
+    } else { // A message payload packet
+
+    }
+
+}
+