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/* $Id: plugin_sample.c,v 1.1 2004/01/06 17:33:45 reinelt Exp $
*
* plugin template
*
* Copyright 2003 Michael Reinelt <reinelt@eunet.at>
*
* 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 1.1 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 <stdlib.h>
#include <string.h>
#include <ctype.h>
// these should always be included
#include "debug.h"
#include "plugin.h"
// 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;
}
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