NAME¶

pvm_initsend - Clear default send buffer and specify message encoding.

SYNOPSIS¶

C	int bufid = pvm_initsend( int encoding )


Fortran	call pvmfinitsend( encoding, bufid )

PARAMETERS¶

encoding

Integer specifying the next message's encoding scheme.

Options in C are:
	Encoding value		MEANING
	PvmDataDefault	0	XDR
	PvmDataRaw	1	no encoding
	PvmDataInPlace	2	data left in place
Option names are in Fortran are:
	Encoding value		MEANING
	PVMDEFAULT	0	XDR
	PVMRAW	1	no encoding
	PVMINPLACE	2	data left in place

bufid

Integer returned containing the message buffer identifier. Values less than zero indicate an error.

DESCRIPTION¶

The routine pvm_initsend clears the send buffer and prepares it for packing a new message. The encoding scheme used for the packing is set by encoding. XDR encoding is used by default because PVM can not know if the user is going to add a heterogeneous machine before this message is sent. If the user knows that the next message will only be sent to a machine that understands the native format, then he can use PvmDataRaw encoding and save on encoding costs.

PvmDataInPlace encoding specifies that data be left in place during packing. The message buffer only contains the sizes and pointers to the items to be sent. When pvm_send is called the items are copied directly out of the user's memory. This option decreases the number of times a message is copied at the expense of requiring the user to not modify the items between the time they are packed and the time they are sent.

If pvm_initsend is successful, then bufid will contain the message buffer identifier. If some error occurs then bufid will be < 0.

RESTRICTIONS¶

PvmDataInPlace allows only dense (stride = 1) data in version 3.3. It cannot be used on shared memory (*MP) architectures; a PvmNotImpl error will occur at send time.

EXAMPLES¶

C:
	bufid = pvm_initsend( PvmDataDefault );
	info = pvm_pkint( array, 10, 1 );
	msgtag = 3 ;
	info = pvm_send( tid, msgtag );

Fortran:
	CALL PVMFINITSEND(PVMRAW, BUFID)
	CALL PVMFPACK( REAL4, DATA, 100, 1, INFO )
	CALL PVMFSEND( TID, 3, INFO )

ERRORS¶

These error conditions can be returned by pvm_initsend

PvmBadParam

giving an invalid encoding value

PvmNoMem

Malloc has failed. There is not enough memory to create the buffer

SEE ALSO¶

pvm_mkbuf(3PVM)