@@ -256,6 +256,20 @@ uint32_t odp_packet_seg_len(odp_packet_t pkt);
uint32_t odp_packet_len(odp_packet_t pkt);
/**
+ * Packet unshared data len
+ *
+ * Returns the sum of data lengths over all unshared packet segments. These
+ * are the only bytes that should be modified by the caller. The rest of the
+ * packet should be treated as read only. odp_packet_unshared_len() will be
+ * equal to odp_packet_len() if odp_packet_is_ref() is 0.
+ *
+ * @param pkt Packet handle
+ *
+ * @return Packet unshared data length
+ */
+uint32_t odp_packet_unshared_len(odp_packet_t pkt);
+
+/**
* Packet headroom length
*
* Returns the current packet level headroom length.
@@ -795,7 +809,7 @@ uint32_t odp_packet_seg_data_len(odp_packet_t pkt, odp_packet_seg_t seg);
* data pointers. Otherwise, all old pointers remain valid.
*
* The resulting packet is always allocated from the same pool as
- * the destination packet. The source packet may have been allocate from
+ * the destination packet. The source packet may have been allocated from
* any pool.
*
* On failure, both handles remain valid and packets are not modified.
@@ -848,6 +862,164 @@ int odp_packet_split(odp_packet_t *pkt, uint32_t len, odp_packet_t *tail);
/*
*
+ * References
+ * ********************************************************
+ *
+ */
+
+/**
+ * Create a static reference to a packet
+ *
+ * A static reference is used to obtain an additional handle for referring to
+ * a packet so that the storage behind it is not freed until all references to
+ * the packet are freed. This can be used, for example, to support efficient
+ * retransmission processing.
+ *
+ * The intent of a static reference is that both the packet and the returned
+ * reference to it will be treated as read only after this call. Results are
+ * undefined if this restriction is not observed.
+ *
+ * Static references have restrictions but may have performance advantages on
+ * some platforms if the caller does not intend to modify the reference
+ * packet. If modification is needed (e.g., to prefix a unique header onto the
+ * packet) then odp_packet_ref() or odp_packet_ref_pkt() should be used.
+ *
+ * @param pkt Handle of the packet for which a static reference is
+ * to be created.
+ *
+ * @return Handle of the static reference packet
+ * @retval ODP_PACKET_INVALID Operation failed. pkt remains unchanged.
+ */
+odp_packet_t odp_packet_ref_static(odp_packet_t pkt);
+
+/**
+ * Create a reference to a packet
+ *
+ * Create a dynamic reference to a packet starting at a specified byte
+ * offset. This reference may be used as an argument to header manipulation
+ * APIs to prefix a unique header onto the shared payload. The storage
+ * associated with the referenced packet is not freed until all references to
+ * it are freed, which permits easy multicasting or retransmission processing
+ * to be performed. Following a successful call, the shared portions of the
+ * referenced packet packet should be treated as read only. Results are
+ * undefined if this restriction is not observed.
+ *
+ * This operation logically prepends a zero-length header onto the referenced
+ * packet beginning at the specified offset. This header is always drawn from
+ * the same pool as the referenced packet.
+ *
+ * Because references are unique packets, any bytes pushed onto the head of a
+ * reference via odp_packet_push_head() or odp_packet_extend_head() are unique
+ * to this reference and are not seen by the referenced packet or by any other
+ * reference to the same packet. Similarly, any bytes pushed onto the
+ * head of the referenced packet are not visible to any reference created
+ * prior to the push operation.
+ *
+ * Note that the existence of references does not in any way change the
+ * requirement that a single packet handle may only be manipulated by one
+ * thread at a time. The odp_packet_unshared_len() API may be used to
+ * determine the number of bytes starting at offset zero that are unique to
+ * this packet handle. Only these bytes should be considered modifiable. All
+ * other bytes accessible from this handle should be treated as read only.
+ *
+ * The packet used as input to this routine may itself by a reference to
+ * some other packet. Implementations that are unable to support such
+ * compound references without copies MAY perform a packet copy operation
+ * to return a valid reference in response to this call.
+ *
+ * If the caller does not indend to push a header onto either the returned
+ * reference or the packet being referenced, or otherwise modify either
+ * packet, the odp_packet_ref_static() API may be used. This may be a more
+ * efficient means of obtaining another reference to a packet if both will be
+ * treated as read only.
+ *
+ * @param pkt Handle of the packet for which a reference is to be
+ * created.
+ *
+ * @param offset Byte offset in pkt at which the shared reference is to
+ * begin. This must be in the range 0..odp_packet_len(pkt)-1.
+ *
+ * @return Handle of the reference packet
+ * @retval ODP_PACKET_INVALID Operation failed. pkt remains unchanged.
+ *
+
+ */
+odp_packet_t odp_packet_ref(odp_packet_t pkt, uint32_t offset);
+
+/**
+ * Create a reference to another packet from a header packet
+ *
+ * Create a dynamic reference to a packet starting at a specified byte offset
+ * by prepending a supplied header packet. The resulting reference consists of
+ * the unshared header followed by the shared referenced packet starting at
+ * the specified offset. This shared portion should be regarded as read
+ * only. The storage associated with the shared portion of the reference is
+ * not freed until all references to it are freed, which permits easy
+ * multicasting or retransmission processing to be performed.
+ *
+ * Because references are unique packets, any bytes pushed onto the head of a
+ * reference via odp_packet_push_head() or odp_packet_extend_head() are unique
+ * to this reference and are not seen by the referenced packet or by any other
+ * reference to the same packet. Similarly, any bytes pushed onto the
+ * head of the referenced packet are not visible to any reference created
+ * prior to the push operation.
+ *
+ * Note that the existence of references does not in any way change the
+ * requirement that a single packet handle may only be manipulated by one
+ * thread at a time. The odp_packet_unshared_len() API may be used to
+ * determine the number of bytes starting at offset zero that are unique to
+ * this packet handle. Only these bytes should be considered modifiable. All
+ * other bytes accessible from this handle should be treated as read only.
+ *
+ * Either packet used as input to this routine may itself by a reference to
+ * some other packet. Implementations that are unable to support such
+ * compound references without copies MAY perform a packet copy operation
+ * to return a valid reference in response to this call.
+ *
+ * The packets used as input to this routine should be drawn from the same
+ * pool. Results are undefined if this restriction is not observed.
+ *
+ * odp_packet_pool() on the returned reference returns the pool id of the
+ * header packet.
+ *
+ * @param pkt Handle of the packet for which a reference is to be
+ * created.
+ *
+ * @param offset Byte offset in pkt at which the shared reference is to
+ * begin. Must be in the range 0..odp_packet_len(pkt)-1.
+ *
+ * @param hdr Handle of the header packet to be prefixed onto pkt to create
+ * the reference. If this is specified as ODP_PACKET_INVALID,
+ * this call is equivalent to odp_packet_ref(). The supplied hdr
+ * must be distinct from pkt and results are undefined if an
+ * attempt is made to create circular references.
+ *
+ * @return Handle of the reference packet. This may or may not be the
+ * same as the input hdr packet. The caller should only use this
+ * handle since the original hdr packet no longer has any
+ * independent existence.
+ *
+ * @retval ODP_PACKET_INVALID Operation failed. Both pkt and hdr are unchanged.
+ */
+odp_packet_t odp_packet_ref_pkt(odp_packet_t pkt, uint32_t offset,
+ odp_packet_t hdr);
+
+/**
+ * Test if a packet is a reference
+ *
+ * A packet is a reference if any other packet handles exist that share any
+ * data bytes with this packet.
+ *
+ * @param pkt Packet handle
+ *
+ * @retval 0 Packet is not a reference. All bytes in this packet are unshared.
+ * @retval 1 Packet is a reference. One or more other packet handles exist
+ * that share bytes with this packet.
+ */
+int odp_packet_is_ref(odp_packet_t pkt);
+
+/*
+ *
* Copy
* ********************************************************
*
Introduce three new APIs that support efficient sharing of portions of packets. odp_packet_ref_static() creates an alias for a base packet odp_packet_ref() creates a reference to a base packet odp_packet_ref_pkt() creates a reference to a base packet from a supplied header packet In addition, two other APIs simplify working with references odp_packet_is_ref() says whether a packet is a reference odp_packet_unshared_len() gives the sum of data lengths over all unshared packet segments. These are the only bytes of the packet that may be modified safely. Signed-off-by: Bill Fischofer <bill.fischofer@linaro.org> --- include/odp/api/spec/packet.h | 174 +++++++++++++++++++++++++++++++++++++++++- 1 file changed, 173 insertions(+), 1 deletion(-) -- 2.7.4