int info = pvm_unpackf( const char *fmt, ... )
int info = pvm_upkbyte( char *xp, int nitem, int stride)
int info = pvm_upkcplx( float *cp, int nitem, int stride)
int info = pvm_upkdcplx( double *zp, int nitem, int stride)
int info = pvm_upkdouble( double *dp, int nitem, int stride)
int info = pvm_upkfloat( float *fp, int nitem, int stride)
int info = pvm_upkint( int *ip, int nitem, int stride)
int info = pvm_upkuint( unsigned int *ip, int nitem, int stride )
int info = pvm_upkushort( unsigned short *ip, int nitem, int stride )
int info = pvm_upkulong( unsigned long *ip, int nitem, int stride )
int info = pvm_upklong( long *ip, int nitem, int stride)
int info = pvm_upkshort( short *jp, int nitem, int stride)
int info = pvm_upkstr( char *sp ) Fortran
call pvmfunpack( what, xp, nitem, stride, info )
STRING 0 REAL4 4 BYTE1 1 COMPLEX8 5 INTEGER2 2 REAL8 6 INTEGER4 3 COMPLEX16 7
An exception is pvm_upkstr() which by definition unpacks a NULL terminated character string and thus does not need nitem or stride arguments. The Fortran routine pvmfunpack( STRING, ... ) expects nitem to be the number of characters in the string and stride to be 1.
If the unpacking is successful, info will be 0. If some error occurs then info will be < 0.
A single variable (not an array) can be unpacked by setting nitem = 1 and stride = 1.
The routine pvm_unpackf() uses a printf-like format expression
to specify what and how to unpack data from the receive buffer.
All variables are passed as addresses.
A BNF-like description of the format syntax is:
format : null | init | format fmt
init : null | '%' '+'
fmt : '%' count stride modifiers fchar
fchar : 'c' | 'd' | 'f' | 'x' | 's'
count : null | [0-9]+ | '*'
stride : null | '.' ( [0-9]+ | '*' )
modifiers : null | modifiers mchar
mchar : 'h' | 'l' | 'u'
+ means initsend - must match an int (how) in the param list. c pack/unpack bytes d integer f float x complex float s string Modifiers: h short (int) l long (int, float, complex float) u unsigned (int)
Future extensions to the what argument in pvmfunpack will include 64 bit types when XDR encoding of these types is available. Meanwhile users should be aware that precision can be lost when passing data from a 64 bit machine like a Cray to a 32 bit machine like a SPARCstation. As a mnemonic the what argument name includes the number of bytes of precision to expect. By setting encoding to PVMRAW (see pvmfinitsend) data can be transferred between two 64 bit machines with full precision even if the PVM configuration is heterogeneous.
Messages should be unpacked exactly like they were packed to insure data integrity. Packing integers and unpacking them as floats will often fail because a type encoding will have occurred transferring the data between heterogeneous hosts. Packing 10 integers and 100 floats then trying to unpack only 3 integers and the 100 floats will also fail.
C: info = pvm_recv( tid, msgtag ); info = pvm_upkstr( string ); info = pvm_upkint( &size, 1, 1 ); info = pvm_upkint( array, size, 1 ); info = pvm_upkdouble( matrix, size*size, 1 ); int count, *iarry; double darry; pvm_unpackf("%d", &count); pvm_unpackf("%*d %4lf", count, iarry, darry); Fortran: CALL PVMFRECV( TID, MSGTAG, INFO ); CALL PVMFUNPACK( INTEGER4, NSIZE, 1, 1, INFO ) CALL PVMFUNPACK( STRING, STEPNAME, 8, 1, INFO ) CALL PVMFUNPACK( REAL4, A(5,1), NSIZE, NSIZE , INFO )