[Tinyos-devel] Proposed patch to TinyOS C SDK

[Eric Decker]

Along those lines.  Namely keeping the message structure structure opaque.

I was wondering if we could add something like the following:

/**
 *   move the tmsg data pointer to an arbitrary place with arbitrary length.
 *  Useful for moving over encapsulations.
 **/
void reset_tmsg(tmsg_t *msg, void *packet, size_t len);

An example of its use is:

    if (len < 1 + SPACKET_SIZE ||
        packet[0] != SERIAL_TOS_SERIAL_ACTIVE_MESSAGE_ID) {
      fprintf(stderr, "*** non-AM packet (type %d, len %d (%0x)): ",
              packet[0], len, len);
      hexprint(packet, len);
      continue;
    }
    msg = new_tmsg(packet + 1, len - 1);
    if (!msg) {
      fprintf(stderr, "*** new_tmsg failed (null)\n");
      exit(2);
    }
    dest = spacket_header_dest_get(msg);
    src  = spacket_header_src_get(msg);
    len  = spacket_header_length_get(msg);
    group= spacket_header_group_get(msg);
    stype= spacket_header_type_get(msg);
    if (debug) {
      fprintf(stderr, "*** dest %04x, src %04x, len %02x, group %02x, type
%02x\n",
             dest, src, len, group, stype);
    }

***

   reset_tmsg(msg, ((uint8_t *)tmsg_data(msg)) + SPACKET_SIZE,
tmsg_length(msg) - spacket_data_offset(0));

***

    switch(stype) {
      case MM3_DATA_MSG_AM_TYPE:
        process_mm3_data(msg);
        break;

      default:
        break;
    }
    free_tmsg(msg);
    free((void *)packet);


Would it be possible to get this interface added to the message library?

eric


diff attached below:

Index: support/sdk/c/sf/message.c
===================================================================
RCS file: /cvsroot/tinyos/tinyos-2.x/support/sdk/c/sf/message.c,v
retrieving revision 1.1
diff -u -r1.1 message.c
--- support/sdk/c/sf/message.c  5 Dec 2007 22:49:46 -0000       1.1
+++ support/sdk/c/sf/message.c  24 Jun 2008 07:30:00 -0000
@@ -18,6 +18,14 @@
   size_t len;
 };

+void reset_tmsg(tmsg_t *msg, void *packet, size_t len)
+{
+  if (!msg)
+    return;
+  msg->data = packet;
+  msg->len  = len;
+}
+
 tmsg_t *new_tmsg(void *packet, size_t len)
 {
   tmsg_t *x = malloc(sizeof(tmsg_t));
Index: support/sdk/c/sf/message.h
===================================================================
RCS file: /cvsroot/tinyos/tinyos-2.x/support/sdk/c/sf/message.h,v
retrieving revision 1.1
diff -u -r1.1 message.h
--- support/sdk/c/sf/message.h  5 Dec 2007 22:49:46 -0000       1.1
+++ support/sdk/c/sf/message.h  24 Jun 2008 07:30:00 -0000
@@ -33,6 +33,11 @@
 */
 void (*tmsg_set_fail(void (*fn)(void)))(void);

+/** reset the data pointer and length of the tmsg struct
+ *  usefull when moving over encapsulations.
+ */
+void reset_tmsg(tmsg_t *msg, void *packet, size_t len) ;
+
 /**
  * Create a message buffer from array 'packet' of 'len' bytes
  */


On Tue, Jun 17, 2008 at 8:54 AM, David Gay <dgay42 at gmail.com> wrote:

> On Wed, May 28, 2008 at 4:57 AM, Dima Kogan <dkogan at cds.caltech.edu>
> wrote:
> > I found an error in message.[ch] in the TinyOS C SDK.
> >
> > Currently the definition of the tmsg structure is in message.c:
> >
> > struct tmsg {
> >  uint8_t *data;
> >  size_t len;
> > };
> >
> > It really should be in message.h instead, in order to make this
> > structure available to external programs that want to use messages. In
> > particular, mig-generated C code needs to do this. Objections?
>
> Yes - it was placed in message.c as it's supposed to be an abstract
> data type. The methods in message.h should be giving you all the
> access you need.
>
> David, answering slowly.
> _______________________________________________
> Tinyos-devel mailing list
> Tinyos-devel at millennium.berkeley.edu
> https://www.millennium.berkeley.edu/cgi-bin/mailman/listinfo/tinyos-devel
>



-- 
Eric B. Decker
Senior (over 50 :-) Researcher
Autonomous Systems Lab
Jack Baskin School of Engineering
UCSC
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