From: Kenneth H. Fairfield [Kenneth.H.Fairfield@intel.com]
Sent: Thursday, November 15, 2001 1:44 PM
To: Info-VAX@Mvb.Saic.Com
Subject: CJL's NOTLIB_PAGINATE.C (Was: Re: LIB$xxx)

   By request (well _one_ request :-) here's a copy of Carl Lydick's
original comp.os.vms post showing how to make LIB$PUT_OUTPUT "page"
its output.  Enjoy!

    -Ken
-----------------------------------------------------------------------


Someone recently complained about the fact that applications using
LBR$OUTPUT_HELP to display help don't paginate the results.  Well, I've written
a small set of routines that allow one to do such pagination.  They won't, of
course, help at all with utilities already out there, but if you're planning to
write an application that uses LBR$OUTPUT_HELP (or any other application that
writes to SYS$OUTPUT and for which you'd like to have the results paginated,
you might find them useful.

NOTLIB_PAGINATE_OUTPUT has the same semantics as LIB$PUT_OUTPUT, but, if the
output device is a terminal, paginates the output.  NOTLIB_PAGINATE_INPUT has
the same semantics as LIB$GET_INPUT, but resets the line counter used by
NOTLIB_PAGINATE_OUTPUT.  NOTLIB_PAGINATE_RESET resets the static variables used
by NOTLIB_PAGINATE_OUTPUT to their initial state.

#include dvidef
#include descrip
long stat;
#define ckstat(x) if (((stat = x) & 7) != 1) return stat
notlib_paginate_output(struct dsc$descriptor *string)
{       return notlib_paginate(0, string);
}

notlib_paginate_input(struct dsc$descriptor *result, struct dsc$descriptor
        *prompt, unsigned short *reslen)
{       notlib_paginate(1, 0);
        return LIB$GET_INPUT(result, prompt, reslen);
}

notlib_paginate_reset()
{       return notlib_paginate(2, 0);
}

notlib_paginate(int action, struct dsc$descriptor *string)
{       static int paglen = 0, initialized = 0, curline = 0, istty = 0;
        static $DESCRIPTOR(devnam, "SYS$OUTPUT");
        static char buffer[80];
        static $DESCRIPTOR(result, buffer);
        static $DESCRIPTOR(prompt, "Hit return to continue");

        if(action == 2)
        {       initialized = 0;
                return 1;
        }
        else if (action == 1)
                curline = 0;
        else if (action == 0)
        {       if (initialized == 0)
                {       initialized = 1;
                        ckstat(LIB$GETDVI(&DVI$_TRM, 0, &devnam, &istty));
                        ckstat(LIB$GETDVI(&DVI$_TT_PAGE, 0, &devnam, &paglen));
                        curline = 0;
                }
                if (istty && (curline >= paglen - 1))
                {       ckstat(LIB$GET_INPUT(&result, &prompt));
                        curline = 0;
                }
                curline++;
                return LIB$PUT_OUTPUT(string);
        }
}
--------------------------------------------------------------------------------
Carl J Lydick | INTERnet: CARL@SOL1.GPS.CALTECH.EDU | NSI/HEPnet: SOL1::CARL

Disclaimer:  Hey, I understand VAXen and VMS.  That's what I get paid for.  My
understanding of astronomy is purely at the amateur level (or below).  So
unless what I'm saying is directly related to VAX/VMS, don't hold me or my
organization responsible for it.  If it IS related to VAX/VMS, you can try to
hold me responsible for it, but my organization had nothing to do with it.