archived-lcd4linux/plugin_sample.c

/* $Id: plugin_sample.c,v 1.8 2004/06/26 12:05:00 reinelt Exp $
 *
 * plugin template
 *
 * Copyright 2003 Michael Reinelt <reinelt@eunet.at>
 * Copyright 2004 The LCD4Linux Team <lcd4linux-devel@users.sourceforge.net>
 *
 * This file is part of LCD4Linux.
 *
 * LCD4Linux is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2, or (at your option)
 * any later version.
 *
 * LCD4Linux is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 *
 *
 * $Log: plugin_sample.c,v $
 * Revision 1.8  2004/06/26 12:05:00  reinelt
 *
 * uh-oh... the last CVS log message messed up things a lot...
 *
 * Revision 1.7  2004/06/26 09:27:21  reinelt
 *
 * added '-W' to CFLAGS
 * changed all C++ comments to C ones
 * cleaned up a lot of signed/unsigned mistakes
 *
 * Revision 1.6  2004/06/01 06:04:25  reinelt
 *
 * made README.Plugins and plugin_sample up to date.
 *
 * Revision 1.5  2004/03/03 03:47:04  reinelt
 * big patch from Martin Hejl:
 * - use qprintf() where appropriate
 * - save CPU cycles on gettimeofday()
 * - add quit() functions to free allocated memory
 * - fixed lots of memory leaks
 *
 * Revision 1.4  2004/01/30 20:57:56  reinelt
 * HD44780 patch from Martin Hejl
 * dmalloc integrated
 *
 * Revision 1.3  2004/01/29 04:40:02  reinelt
 * every .c file includes "config.h" now
 *
 * Revision 1.2  2004/01/13 10:03:01  reinelt
 * new util 'hash' for associative arrays
 * new plugin 'cpuinfo'
 *
 * Revision 1.1  2004/01/06 17:33:45  reinelt
 *
 * Evaluator: functions with variable argument lists
 * Evaluator: plugin_sample.c and README.Plugins added
 *
 */

/* 
 * exported functions:
 *
 * int plugin_init_sample (void)
 *  adds various functions
 *
 */


/* define the include files you need */
#include "config.h"

#include <stdlib.h>
#include <string.h>
#include <ctype.h>

/* these should always be included */
#include "debug.h"
#include "plugin.h"

#ifdef WITH_DMALLOC
#include <dmalloc.h>
#endif



/* sample function 'mul2' */
/* takes one argument, a number */
/* multiplies the number by 2.0 */
/* Note: all local functions should be declared 'static' */

static void my_mul2 (RESULT *result, RESULT *arg1)
{
  double param;
  double value;

  /* Get Parameter */
  /* R2N stands for 'Result to Number' */
  param = R2N(arg1);
  
  /* calculate value */
  value = param*2.0;
  
  /* store result */
  /* when called with R_NUMBER, it assumes the */
  /* next parameter to be a pointer to double */
  SetResult(&result, R_NUMBER, &value); 
}


/* sample function 'mul3' */
/* takes one argument, a number */
/* multiplies the number by 3.0 */
/* same as 'mul2', but shorter */

static void my_mul3 (RESULT *result, RESULT *arg1)
{
  /* do it all in one line */
  double value = R2N(arg1) * 3.0;

  /* store result */
  SetResult(&result, R_NUMBER, &value); 
}


/* sample function 'diff' */
/* takes two arguments, both numbers */
/* returns |a-b| */

static void my_diff (RESULT *result, RESULT *arg1, RESULT *arg2)
{
  /* do it all in one line */
  double value = R2N(arg1) - R2N(arg2);
  
  /* some more calculations... */
  if (value < 0) value = -value;
  
  /* store result */
  SetResult(&result, R_NUMBER, &value); 
}


/* sample function 'answer' */
/* takes no argument! */
/* returns the answer to all questions */

static void my_answer (RESULT *result)
{
  /* we have to declare a variable because */
  /* SetResult needs a pointer  */
  double value = 42;
  
  /* store result */
  SetResult(&result, R_NUMBER, &value); 
}


/* sample function 'length' */
/* takes one argument, a string */
/* returns the string length */

static void my_length (RESULT *result, RESULT *arg1)
{
  /* Note #1: value *must* be double!  */
  /* Note #2: R2S stands for 'Result to String' */
  double value = strlen(R2S(arg1));
  
  /* store result */
  SetResult(&result, R_NUMBER, &value); 
}



/* sample function 'upcase' */
/* takes one argument, a string */
/* returns the string in upper case letters */

static void my_upcase (RESULT *result, RESULT *arg1)
{
  char *value, *p;
  
  /* create a local copy of the argument */
  /* Do *NOT* try to modify the original string! */
  value = strdup(R2S(arg1));
  
  /* process the string */
  for (p = value; *p != '\0'; p++)
    *p = toupper(*p);

  /* store result */
  /* when called with R_STRING, it assumes the */
  /* next parameter to be a pointer to a string */
  /* 'value' is already a char*, so use 'value', not '&value' */
  SetResult(&result, R_STRING, value); 

  /* free local copy again */
  /* Note that SetResult() makes its own string copy  */
  free (value);
}


/* sample function 'cat' */
/* takes variable number of arguments, all strings */
/* returns all prameters concatenated */

static void my_concat (RESULT *result, int argc, RESULT *argv[])
{
  int i, len;
  char *value, *part;
  
  /* start with a empty string */
  value = strdup("");
  
  /* process all arguments */
  for (i = 0; i < argc; i++) {
    part = R2S(argv[i]);
    len = strlen(value)+strlen(part);
    value = realloc(value, len+1);
    strcat(value, part);
  }

  /* store result */
  SetResult(&result, R_STRING, value); 

  /* free local string */
  free (value);
}


/* plugin initialization */
/* MUST NOT be declared 'static'! */
int plugin_init_sample (void)
{

  /* register all our cool functions */
  /* the second parameter is the number of arguments */
  /* -1 stands for variable argument list */
  AddFunction ("mul2",    1, my_mul2);
  AddFunction ("mul3",    1, my_mul3);
  AddFunction ("answer",  0, my_answer);
  AddFunction ("diff",    2, my_diff);
  AddFunction ("length",  1, my_length);
  AddFunction ("upcase",  1, my_upcase);
  AddFunction ("concat", -1, my_concat);

  return 0;
}

void plugin_exit_sample(void) 
{
  /* free any allocated memory */
  /* close filedescriptors */
}