Example of Print Formatter

This example shows how print formatters can interact with the documented printer formatter subroutines. The procedure for writing a print formatter involves four steps:

1. Creating a print formatter source file as shown below.
2. Creating an imports file.
3. Creating an exports file.
4. Compiling and linking the print formatter.

Create the Print Formatter Source File

Use an ASCII editor to create a formatter source file named sample.c . The file should contain the following lines:

#include <stdio.h>
#include <piostruct.h>
 
/* STRING CONSTANTS */
/* Initialize Printer, Restore Printer, Form Feed */
#define INIT_CMD    "ci"
#define REST_CMD    "cr"
#define FF_CMD      "af"

/* INTEGER and STRING VARIABLES */
/* page length, page width, top margin, bottom margin */
#define Pglen          (*(_Pglen + piomode))
#define Pgwidth        (*(_Pgwidth + piomode))
#define Tmarg          (*(_Tmarg + piomode))
#define Bmarg          (*(_Bmarg + piomode))

/* indentation, begin page, form feed?, pass-through? */
#define Indent         (*(_Indent + piomode))
#define Beginpg        (*(_Beginpg + piomode))
#define Do_formfeed    (*(_Do_formfeed + piomode))
#define Passthru       (*(_Passthru + piomode))

/* initialize printer?, restore printer? */
#define Init_printer    (*(_Init_printer + piomode))
#define Restoreprinter  (*(_Restoreprinter + piomode))

/* Command names: form feed, vertical increment and decrement */
#define Ff_cmd         (*(_Ff_cmd + piomode))
#define Vincr_cmd      (*(_Vincr_cmd + piomode))
#define Vdecr_cmd      (*(_Vdecr_cmd + piomode))

/* Work variables for vertical increment and decrement */
#define Vincr          (*(_Vincr + piomode))
#define Vdecr          (*(_Vdecr + piomode))

/* Variables referenced by above #defines */
int *_Pglen, *_Pgwidth, *_Tmarg, *_Bmarg, *_Indent, *_Beginpg, *_Do_
formfeed, *_Passthru, *_Init_printer, *_Restoreprinter, *_Vincr, *_V
decr;
struct str_info *_Ff_cmd, *_Vincr_cmd, *_Vdecr_cmd;

/* TABLE OF ATTRIBUTE VALUES */
struct attrparms attrtable[] = { /*
name  data type  lookup  address of pointer */
"_b",  VAR_INT,   NULL,   (union dtypes *) &_Bmarg,
"_g",  VAR_INT,   NULL,   (union dtypes *) &_Beginpg,
"_i",  VAR_INT,   NULL,   (union dtypes *) &_Indent,
"_j",  VAR_INT,   NULL,   (union dtypes *) &_Init_printer,
"_l",  VAR_INT,   NULL,   (union dtypes *) &_Pglen,
"_t",  VAR_INT,   NULL,   (union dtypes *) &_Tmarg,
"_w",  VAR_INT,   NULL,   (union dtypes *) &_Pgwidth,
"_J",  VAR_INT,   NULL,   (union dtypes *) &_Restoreprinter,
"_Z",  VAR_INT,   NULL,   (union dtypes *) &_Do_formfeed,
"wp",  VAR_INT,   NULL,   (union dtypes *) &_Passthru,
"wf",  VAR_STR,   NULL,   (union dtypes *) &_Ff_cmd,
"wi",  VAR_STR,   NULL,   (union dtypes *) &_Vincr_cmd,
"wy",  VAR_STR,   NULL,   (union dtypes *) &_Vdecr_cmd,
"wV",  VAR_INT,   NULL,   (union dtypes *) &_Vincr,
"wD",  VAR_INT,   NULL,   (union dtypes *) &_Vdecr,
NULL,  0     ,   NULL,    NULL };
int pglen, tmarg, bmarg, vpos, vtab_base;
struct shar_vars sharevars;

struct shar_vars * /*** Setup Processing ***/
setup(argc, argv, passthru)
   unsigned argc;
    char *argv[];
    int passthru:
{

/* Initialize variables and command line values */
(void) piogetvals(attrtable, NULL);
(void) piogetopt(argc, argv, NULL, NULL);
/* (need to verify values entered by user) */

/* Initialize work variables */
pglen = Pglen * Vincr;
tmarg = Tmarg * Vincr;
bmarg = Bmarg * Vincr;
piopgskip = Beginpg - 1;

/* Check for pass-through option */
if (Passthru = passthru)
     return(NULL);

/* Initialize pointers to vertical spacing */
/* variables shared with formatter driver  */
/* (Refer to /usr/include/piostruct.h)     */
sharevars._pl            = &pglen;
sharevars._tmarg         = &tmarg;
sharevars._bmarg         = &bmarg;
sharevars._vpos          = &vpos;
sharevars._vtab_base     = &vtab_base;
sharevars._vincr         = &Vincr;
sharevars._vincr_cmd     = (&Vincr_cmd)->ptr;
sharevars._vdecr         = &Vdecr;
sharevars._vdecr_cmd     = (&Vdecr_cmd)->ptr;
sharevars._ff_cmd        = (&Ff_cmd)->ptr;
sharevars._ff_at_eof     = &Do_formfeed;
return(&sharevars);
}

initialize() /*** Initialize the Printer ***/
{
if (Init_printer)
      (void) piocmdout(INIT_CMD, NULL, 0, NULL);
return(0);
}

lineout(fileptr)  /***  Format a Line  ***/
FILE *fileptr;
{
int ch, charcount = 0;
for (ch = 0; ch < Indent; ch++)
          pioputchar(' ');
while ((ch=piogetc(fileptr)) != '\n' && ch != EOF
             && charcount < Pgwidth) {
           charcount++;
            pioputchar(c);
}
vpos += Vincr;
return(charcount);
}

passthru()  /*** Pass-through Option ***/
{
int ch;
while ((ch = piogetc(stdin)) != EOF)
           pioputchar(ch);
if (piodatasent && Do_formfeed)
          (void) piocmdout(FF_CMD, NULL, 0, NULL);
return(0);
}

restore() /*** Restore the Printer ***/
{
if (Restoreprinter)
       (void) piocmdout(REST_CMD, NULL, 0, NULL);
return(0);
}

Compile and Link the Print Formatter

Use an editor to create an imports file named sample.imp . The file should contain the following:

#!
main
piogetvals
piogetopt
piomsgout
pioexit
piomode
piodatasent
piopgskip
statusfile
piocmdout
piogetstr

Use an editor to create an exports file named sample.exp . The file should contain the following:

#!
setup
initialize
passthru
restore
lineout

Enter the following to compile and link the formatter:

cc -o sample -bI:sample.imp -bE:sample.exp sample.c