NAME
pvm_precv - Receive a message directly into a buffer.
SYNOPSIS
C int info = pvm_precv( int tid, int msgtag, char *buf, int len, int datatype, int *atid, int *atag, int *alen )
Fortran call pvmfprecv( tid, msgtag, buf, len, datatype, atid, atag, alen, info )
tid Integer task identifier of sending process (to match).
msgtag Integer message tag (to match). msgtag should be >= 0.
buf Pointer to a buffer to receive into.
len Length of buffer (in multiple of data type size).
datatype
Type of data to which buf points (see below).
atid Returns actual TID of sender.
atag Returns actual message tag.
alen Returns actual message length.
info Returns PvmOk on success. Values less than zero indicate an error.
DISCUSSION
The routine pvm_precv blocks the process until a message with label msgtag has arrived from tid. pvm_precv then places the contents of the message in the supplied buffer, buf, up to a maximum length of len * (size of data type).
pvm_precv can receive messages sent by pvm_psend, pvm_send, pvm_mcast, or pvm_bcast.
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_precv will accept a message from any process which has a matching msgtag. If msgtag = -1 and tid is defined by the user, then pvm_precv will accept any message that is sent from process tid. If tid = -1 and msgtag = -1, then pvm_precv will accept any message from any process.
In C the datatype parameter must be one of the following, depending on the type of data to be unpacked: [Version 3.3.0 - This parameter only determines message length, not data conversion. It only unpacks raw bytes]
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_precv is successful, info will be = 0. If some error occurs then info will be < 0.
pvm_precv is blocking which means the routine waits until a message matching the user specified tid and msgtag arrives at the local pvmd. If the message has already arrived then pvm_precv returns immediately with the message.
pvm_precv does not affect the state of the current receive message buffer (created by the other receive functions).
info = pvm_precv( tid, msgtag, array, cnt, PVM_FLOAT, &src, &rtag, &rlen );
Fortran:
CALL PVMFPRECV( -1, 4, BUF, CNT, REAL4,