NAME

       pvm_recv - Receive a message.

SYNOPSIS

       C    int bufid = pvm_recv( int tid, int msgtag )

       Fortran   call pvmfrecv( tid, msgtag, bufid )

PARAMETERS

       tid     Integer task identifier of sending process supplied by the user.

       msgtag  Integer message tag supplied by the user.  msgtag should be >= 0.

       bufid   Integer  returns  the  value  of the new active receive buffer identifier.  Values
               less than zero indicate an error.

DESCRIPTION

       The routine pvm_recv blocks the process until a message with label msgtag has arrived from
       tid.   pvm_recv  then places the message in a new active receive buffer, which also clears
       the current receive buffer.

       A -1 in msgtag or tid matches anything.  This allows the user the following  options.   If
       tid  =  -1 and msgtag is defined by the user, then pvm_recv will accept a message from any
       process which has a matching msgtag.  If msgtag = -1 and tid is defined by the user,  then
       pvm_recv  will accept any message that is sent from process tid.  If tid = -1 and msgtag =
       -1, then pvm_recv will accept any message from any process.

       The PVM model guarantees the following about message order.  If task 1 sends message A  to
       task  2,  then  task  1  sends message B to task 2, message A will arrive at task 2 before
       message B.  Moreover, if both messages arrive  before  task  2  does  a  receive,  then  a
       wildcard receive will always return message A.

       If  pvm_recv  is  successful,  bufid  will  be  the value of the new active receive buffer
       identifier.  If some error occurs then bufid will be < 0.

       pvm_recv is blocking which means the routine waits  until  a  message  matching  the  user
       specified  tid  and  msgtag  values  arrives at the local pvmd. If the message has already
       arrived then pvm_recv returns immediately with the message.

       Once pvm_recv returns, the data in the message can be  unpacked  into  the  user's  memory
       using the unpack routines.

EXAMPLES

       C:
            tid = pvm_parent();
            msgtag = 4 ;
            bufid = pvm_recv( tid, msgtag );
            info = pvm_upkint( tid_array, 10, 1 );
            info = pvm_upkint( problem_size, 1, 1 );
            info = pvm_upkfloat( input_array, 100, 1 );

       Fortran:
            CALL PVMFRECV( -1, 4, BUFID )
            CALL PVMFUNPACK( INTEGER4, TIDS, 25, 1, INFO )
            CALL PVMFUNPACK( REAL8, MATRIX, 100, 100, INFO )

ERRORS

       These error conditions can be returned by pvm_recv

       PvmBadParam
              giving an invalid tid value, or msgtag < -1.

       PvmSysErr
              pvmd not responding.

SEE ALSO

       pvm_bufinfo(3PVM), pvm_getminfo(3PVM), pvm_nrecv(3PVM), pvm_unpack(3PVM), pvm_probe(3PVM),
       pvm_send(3PVM), pvm_mcast(3PVM)

                                         30 August, 1993                               RECV(3PVM)