X-Git-Url: https://oss.titaniummirror.com/gitweb/?a=blobdiff_plain;f=tos%2Finterfaces%2FPacket.nc;h=47b0c6268bfa81b43f73b2d55599475fe9b08c75;hb=e5533d4cc5eb80845d8e58456a03d2188abda869;hp=2e61a5fb1b7cca08d1cbc04bd289c86805a79888;hpb=ac2bebb860e590c31c6cce5e8c8d3902f2c9ce7e;p=tinyos-2.x.git
diff --git a/tos/interfaces/Packet.nc b/tos/interfaces/Packet.nc
index 2e61a5fb..47b0c626 100644
--- a/tos/interfaces/Packet.nc
+++ b/tos/interfaces/Packet.nc
@@ -94,14 +94,23 @@ interface Packet {
*/
command uint8_t maxPayloadLength();
+
/**
- * Return a pointer to a protocol's payload region in a packet which
- * at least a certain length. If the payload region is smaller than
- * the len parameter, then getPayload returns NULL.
+ * Return a pointer to a protocol's payload region in a packet.
+ * If the caller intends to write to the payload region then
+ * the len parameter must reflect the maximum required
+ * length. If the caller (only) wants to read from the payload
+ * region, then len may be set to the value of
+ * payloadLength(). If the payload region is smaller than
+ * len this command returns NULL. The offset where
+ * the payload region starts within a packet is fixed, i.e. for
+ * a given msg this command will always return the same
+ * pointer or NULL.
*
- * @param msg the packet
+ * @param msg the packet
* @param len the length of payload required
* @return a pointer to the packet's data payload for this layer
+ * or NULL if len is too big
*/
command void* getPayload(message_t* msg, uint8_t len);