Added a new module called "framer" that creates MAC level frames to

the packetbuf from packet attributes. Two framer modules are included,
one that creates 802.15.4 frame headers, and one that creates a
minimal "nullmac"-style header that only contains the link-local
addresses.

core/net/mac/Makefile.mac

@@ -1 +1,2 @@
 CONTIKI_SOURCEFILES += xmac.c nullmac.c lpp.c frame802154.c sicslowmac.c
+CONTIKI_SOURCEFILES += framer.c framer-nullmac.c framer-802154.c

core/net/mac/framer-802154.c

@@ -0,0 +1,179 @@
+/*
+ * Copyright (c) 2009, Swedish Institute of Computer Science.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. Neither the name of the Institute nor the names of its contributors
+ *    may be used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ *
+ * $Id: framer-802154.c,v 1.1 2009/10/19 18:30:03 adamdunkels Exp $
+ */
+
+/**
+ * \file
+ *         MAC framer for IEEE 802.15.4
+ * \author
+ *         Niclas Finne <nfi@sics.se>
+ *         Joakim Eriksson <joakime@sics.se>
+ */
+
+#include "net/mac/framer-802154.h"
+#include "net/mac/frame802154.h"
+#include "net/rime/packetbuf.h"
+
+#define DEBUG 0
+
+#if DEBUG
+#include <stdio.h>
+#define PRINTF(...) printf(__VA_ARGS__)
+#define PRINTADDR(addr) PRINTF(" %02x%02x:%02x%02x:%02x%02x:%02x%02x ", ((uint8_t *)addr)[0], ((uint8_t *)addr)[1], ((uint8_t *)addr)[2], ((uint8_t *)addr)[3], ((uint8_t *)addr)[4], ((uint8_t *)addr)[5], ((uint8_t *)addr)[6], ((uint8_t *)addr)[7])
+#else
+#define PRINTF(...)
+#define PRINTADDR(addr)
+#endif
+
+static uint8_t mac_dsn;
+static uint16_t mac_dst_pan_id = IEEE802154_PANID;
+static uint16_t mac_src_pan_id = IEEE802154_PANID;
+
+/*---------------------------------------------------------------------------*/
+static int
+is_broadcast_addr(uint8_t mode, uint8_t *addr)
+{
+  int i = mode == FRAME802154_SHORTADDRMODE ? 2 : 8;
+  while(i-- > 0) {
+    if(addr[i] != 0xff) {
+      return 0;
+    }
+  }
+  return 1;
+}
+/*---------------------------------------------------------------------------*/
+static int
+create(void)
+{
+  frame802154_t params;
+  uint8_t len;
+
+  /* init to zeros */
+  memset(&params, 0, sizeof(params));
+
+  /* Build the FCF. */
+  params.fcf.frame_type = FRAME802154_DATAFRAME;
+  params.fcf.security_enabled = 0;
+  params.fcf.frame_pending = 0;
+  params.fcf.ack_required = packetbuf_attr(PACKETBUF_ATTR_RELIABLE);
+  params.fcf.panid_compression = 0;
+
+  /* Insert IEEE 802.15.4 (2003) version bit. */
+  params.fcf.frame_version = FRAME802154_IEEE802154_2003;
+
+  /* Increment and set the data sequence number. */
+  params.seq = mac_dsn++;
+/*   params.seq = packetbuf_attr(PACKETBUF_ATTR_PACKET_ID); */
+
+  /* Complete the addressing fields. */
+  /**
+     \todo For phase 1 the addresses are all long. We'll need a mechanism
+     in the rime attributes to tell the mac to use long or short for phase 2.
+  */
+  params.fcf.src_addr_mode = FRAME802154_LONGADDRMODE;
+  params.dest_pid = mac_dst_pan_id;
+
+  /*
+   *  If the output address is NULL in the Rime buf, then it is broadcast
+   *  on the 802.15.4 network.
+   */
+  if(rimeaddr_cmp(packetbuf_addr(PACKETBUF_ADDR_RECEIVER), &rimeaddr_null)) {
+    /* Broadcast requires short address mode. */
+    params.fcf.dest_addr_mode = FRAME802154_SHORTADDRMODE;
+    params.dest_addr.u8[0] = 0xFF;
+    params.dest_addr.u8[1] = 0xFF;
+
+  } else {
+    rimeaddr_copy(&params.dest_addr, packetbuf_addr(PACKETBUF_ADDR_RECEIVER));
+    params.fcf.dest_addr_mode = FRAME802154_LONGADDRMODE;
+  }
+
+  /* Set the source PAN ID to the global variable. */
+  params.src_pid = mac_src_pan_id;
+
+  /*
+   * Set up the source address using only the long address mode for
+   * phase 1.
+   */
+  rimeaddr_copy(&params.src_addr, &rimeaddr_node_addr);
+
+  params.payload = packetbuf_dataptr();
+  params.payload_len = packetbuf_datalen();
+  len = frame802154_hdrlen(&params);
+  if(packetbuf_hdralloc(len)) {
+    frame802154_create(&params, packetbuf_hdrptr(), len);
+
+    PRINTF("P6MAC-UT: %2X", params.fcf.frame_type);
+    PRINTADDR(params.dest_addr.u8);
+    PRINTF("%u %u (%u)\n", len, packetbuf_datalen(), packetbuf_totlen());
+
+    return len;
+  } else {
+    PRINTF("P6MAC-UT: too large header: %u\n", len);
+    return 0;
+  }
+}
+/*---------------------------------------------------------------------------*/
+static int
+parse(void)
+{
+  frame802154_t frame;
+  int len;
+  len = packetbuf_datalen();
+  if(frame802154_parse(packetbuf_dataptr(), len, &frame) &&
+     packetbuf_hdrreduce(len - frame.payload_len)) {
+    if(frame.fcf.dest_addr_mode) {
+      if(frame.dest_pid != mac_src_pan_id &&
+         frame.dest_pid != FRAME802154_BROADCASTPANDID) {
+        /* Packet to another PAN */
+        PRINTF("P6MAC: for another pan %u\n", frame.dest_pid);
+        return 0;
+      }
+      if(!is_broadcast_addr(frame.fcf.dest_addr_mode, frame.dest_addr.u8)) {
+        packetbuf_set_addr(PACKETBUF_ADDR_RECEIVER, &frame.dest_addr);
+      }
+    }
+    packetbuf_set_addr(PACKETBUF_ADDR_SENDER, &frame.src_addr);
+    packetbuf_set_attr(PACKETBUF_ATTR_RELIABLE, frame.fcf.ack_required);
+    packetbuf_set_attr(PACKETBUF_ATTR_PACKET_ID, frame.seq);
+
+    PRINTF("P6MAC-IN: %2X", frame.fcf.frame_type);
+    PRINTADDR(packetbuf_addr(PACKETBUF_ADDR_SENDER));
+    PRINTADDR(packetbuf_addr(PACKETBUF_ADDR_RECEIVER));
+    PRINTF("%u (%u)\n", packetbuf_datalen(), len);
+
+    return len - frame.payload_len;
+  }
+  return 0;
+}
+/*---------------------------------------------------------------------------*/
+const struct framer framer_802154 = {
+  create, parse
+};

core/net/mac/framer-802154.h

@@ -0,0 +1,47 @@
+/*
+ * Copyright (c) 2009, Swedish Institute of Computer Science.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. Neither the name of the Institute nor the names of its contributors
+ *    may be used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ *
+ * $Id: framer-802154.h,v 1.1 2009/10/19 18:30:03 adamdunkels Exp $
+ */
+
+/**
+ * \file
+ *         A MAC framer for IEEE 802.15.4
+ * \author
+ *         Niclas Finne <nfi@sics.se>
+ *         Joakim Eriksson <joakime@sics.se>
+ */
+
+#ifndef __FRAMER_802154_H__
+#define __FRAMER_802154_H__
+
+#include "net/mac/framer.h"
+
+extern const struct framer framer_802154;
+
+#endif /* __FRAMER_802154_H__ */

core/net/mac/framer-nullmac.c

@@ -0,0 +1,96 @@
+/*
+ * Copyright (c) 2009, Swedish Institute of Computer Science.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. Neither the name of the Institute nor the names of its contributors
+ *    may be used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ *
+ * $Id: framer-nullmac.c,v 1.1 2009/10/19 18:30:03 adamdunkels Exp $
+ */
+
+/**
+ * \file
+ *         MAC framer for nullmac
+ * \author
+ *         Niclas Finne <nfi@sics.se>
+ *         Joakim Eriksson <joakime@sics.se>
+ */
+
+#include "net/mac/framer-nullmac.h"
+#include "net/rime/packetbuf.h"
+
+#define DEBUG 0
+
+#if DEBUG
+#include <stdio.h>
+#define PRINTF(...) printf(__VA_ARGS__)
+#define PRINTADDR(addr) PRINTF(" %02x%02x:%02x%02x:%02x%02x:%02x%02x ", ((uint8_t *)addr)[0], ((uint8_t *)addr)[1], ((uint8_t *)addr)[2], ((uint8_t *)addr)[3], ((uint8_t *)addr)[4], ((uint8_t *)addr)[5], ((uint8_t *)addr)[6], ((uint8_t *)addr)[7])
+#else
+#define PRINTF(...)
+#define PRINTADDR(addr)
+#endif
+
+struct nullmac_hdr {
+  rimeaddr_t receiver;
+  rimeaddr_t sender;
+};
+
+/*---------------------------------------------------------------------------*/
+static int
+create(void)
+{
+  struct nullmac_hdr *hdr;
+
+  if(packetbuf_hdralloc(sizeof(struct nullmac_hdr))) {
+    hdr = packetbuf_hdrptr();
+    rimeaddr_copy(&(hdr->sender), &rimeaddr_node_addr);
+    rimeaddr_copy(&(hdr->receiver), packetbuf_addr(PACKETBUF_ADDR_RECEIVER));
+    return sizeof(struct nullmac_hdr);
+  }
+  PRINTF("PNULLMAC-UT: too large header: %u\n", len);
+  return 0;
+}
+/*---------------------------------------------------------------------------*/
+static int
+parse(void)
+{
+  struct nullmac_hdr *hdr;
+  hdr = packetbuf_dataptr();
+  if(packetbuf_hdrreduce(sizeof(struct nullmac_hdr))) {
+    packetbuf_set_addr(PACKETBUF_ADDR_SENDER, &(hdr->sender));
+    packetbuf_set_addr(PACKETBUF_ADDR_RECEIVER, &(hdr->receiver));
+
+    PRINTF("PNULLMAC-IN: ");
+    PRINTADDR(packetbuf_addr(PACKETBUF_ADDR_SENDER));
+    PRINTADDR(packetbuf_addr(PACKETBUF_ADDR_RECEIVER));
+    PRINTF("%u (%u)\n", packetbuf_datalen(), len);
+
+    return sizeof(struct nullmac_hdr);
+  }
+  return 0;
+}
+/*---------------------------------------------------------------------------*/
+const struct framer framer_nullmac = {
+  create, parse
+};

core/net/mac/framer-nullmac.h

@@ -0,0 +1,47 @@
+/*
+ * Copyright (c) 2009, Swedish Institute of Computer Science.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. Neither the name of the Institute nor the names of its contributors
+ *    may be used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ *
+ * $Id: framer-nullmac.h,v 1.1 2009/10/19 18:30:03 adamdunkels Exp $
+ */
+
+/**
+ * \file
+ *         MAC framer for nullmac
+ * \author
+ *         Niclas Finne <nfi@sics.se>
+ *         Joakim Eriksson <joakime@sics.se>
+ */
+
+#ifndef __FRAMER_NULLMAC_H__
+#define __FRAMER_NULLMAC_H__
+
+#include "net/mac/framer.h"
+
+extern const struct framer framer_nullmac;
+
+#endif /* __FRAMER_NULLMAC_H__ */

core/net/mac/framer.c

@@ -0,0 +1,60 @@
+/*
+ * Copyright (c) 2009, Swedish Institute of Computer Science.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. Neither the name of the Institute nor the names of its contributors
+ *    may be used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ *
+ * $Id: framer.c,v 1.1 2009/10/19 18:30:03 adamdunkels Exp $
+ */
+
+/**
+ * \file
+ *         A MAC framer is responsible for constructing and parsing
+ *         the header in MAC frames. At least the sender and receiver
+ *         are required to be encoded in the MAC frame headers.
+ * \author
+ *         Niclas Finne <nfi@sics.se>
+ *         Joakim Eriksson <joakime@sics.se>
+ */
+
+#include "contiki.h"
+#include "net/mac/framer.h"
+#include "net/mac/framer-nullmac.h"
+
+const struct framer *framer_current;
+
+/*---------------------------------------------------------------------------*/
+const struct framer *
+framer_get(void)
+{
+  return framer_current != NULL ? framer_current : &framer_nullmac;
+}
+/*---------------------------------------------------------------------------*/
+void
+framer_set(const struct framer *f)
+{
+  framer_current = f;
+}
+/*---------------------------------------------------------------------------*/

core/net/mac/framer.h

@@ -0,0 +1,58 @@
+/*
+ * Copyright (c) 2009, Swedish Institute of Computer Science.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. Neither the name of the Institute nor the names of its contributors
+ *    may be used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ *
+ * $Id: framer.h,v 1.1 2009/10/19 18:30:03 adamdunkels Exp $
+ */
+
+/**
+ * \file
+ *         A MAC framer is responsible for constructing and parsing
+ *         the header in MAC frames. At least the sender and receiver
+ *         are required to be encoded in the MAC frame headers.
+ * \author
+ *         Niclas Finne <nfi@sics.se>
+ *         Joakim Eriksson <joakime@sics.se>
+ */
+
+#ifndef __FRAMER_H__
+#define __FRAMER_H__
+
+struct framer {
+
+  int (* create)(void);
+  int (* parse)(void);
+
+};
+
+extern const struct framer *framer_current;
+
+const struct framer *framer_get(void);
+
+void framer_set(const struct framer *f);
+
+#endif /* __FRAMER_H__ */