Changes between Version 1 and Version 2 of MessagePassing

Timestamp:

07/11/13 15:31:56 (13 years ago)

Author:

siegel

Comment:

--

MessagePassing

@@ -10 +10 @@
 $proc procs[NPROCS];
 
+/* There will be one message queue for each pair of prods (i,j).
+ * Each queue is a doubly-linked list of Message objects.
+ */
 typedef struct Message {
   struct Message *<top> next;
@@ -18 +21 @@
 } Message;
 
-typedef struct Comm {
+typedef struct Comm_struct {
   Message *<top> buf_front[NPROCS][NPROCS];
   Message *<top> buf_back[NPROCS][NPROCS];
-} Comm;
+} Comm_struct;
+
+typedef Comm_struct *Comm;
+
+/* As in MPI, when a receive returns, this structure
+ * tells you the source and tag of received message,
+ * which you need if you used wildcards,  Also size.
+ */
+typedef struct Status {
+  int source;
+  int tag;
+  int size;
+} Status;
 
 Comm _Comm_world;
 
+/* The user will use COMM_WORLD */
 Comm *<top> COMM_WORLD = &_Comm_world;
+
+
 
 void init() {
@@ -35 +53 @@
       COMM_WORLD->buf_back[i][j] = NULL;
     }
+}    
+
+void send(int source, void *buf, int size, int tag, int dest, Comm comm) {
+  // create a message
+  Message message;
+
+  message.tag = tag;
+  message.size = size;
+  message.data = $malloc<top>(&mp_heap, size);
+  memcpy(message.data, buf, size);
+  // enqueue on comm->buf_front[i][j] …
+  // update  message.next, message.prev, buf_back[i][j]
+}
+
+// can I use a function as a guard?  not now
+// can always use busy-wait loop?
+boolean probe(…) {
+
+}
+
+void recv(int dest, void *buf, int size, int tag, int source, Comm comm, Status *status) {
+  Message *message;  
+  int message_source;
+  int message_dest;
+  // search the queue looking for the message
+  // also set message_source, message_dest;
+  // and remove message from the queue
   
-
-
-
-
+  if (message.size > size) error…;
+  memcpy(buf, message.data, message.size);
+  status->size = message.size;
+  status->source = message_source;
+  status->dest = message_dest;
+  $free(message->data);
+}
 
 }}}