PURPOSE

Fproj, Fproj32 - projection on buffer

SYNOPSIS


#include <stdio.h>
#include "fml.h"
int
Fproj(FBFR *fbfr, FLDID *fieldid)
#include "fml32.h"
int
Fproj32(FBFR32 *fbfr, FLDID32 *fieldid)

DESCRIPTION

Fproj() is used to update a buffer so as to keep only the desired fields. fbfr is a pointer to a fielded buffer. The desired fields are specified in an array of field identifiers pointed to by fieldid. The last entry in the array must be BADFLDID. The update is done in-place; fields that are not in the result of the projection are deleted from the fielded buffer. The array of field identifiers may be re-arranged (if they are not already in numeric order, they are sorted).

Fproj32 is used with 32-bit FML.

RETURN VALUES

This function returns -1 on error and sets Ferror to indicate the error condition.

ERRORS

Under the following conditions, Fproj() fails and sets Ferror to:

[FALIGNERR]
"fielded buffer not aligned" The buffer does not begin on the proper boundary.
[FNOTFLD]
"buffer not fielded" The buffer is not a fielded buffer or has not been initialized by Finit().

EXAMPLE

#include "fld.tbl.h"
FBFR *fbfr;
FLDID fieldid[20];
fieldid[0] = A;	/* field id for field A */
fieldid[1] = D;	/* field id for field D */
fieldid[2] = BADFLDID;   /* sentinel value */
if(Fproj(fbfr, fieldid)  0)
    F_error("pgm_name");