archived-lcd4linux/plugin_sample.c

/* $Id: plugin_sample.c,v 1.6 2004/06/01 06:04:25 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 1.6  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
}