415 lines
12 KiB
C
415 lines
12 KiB
C
/*
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* Copyright (c) 2004-2005, Swedish Institute of Computer Science.
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. Neither the name of the Institute nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* This file is part of the protothreads library.
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*
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* Author: Adam Dunkels <adam@sics.se>
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*
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* $Id: example-codelock.c,v 1.5 2005/10/06 07:57:08 adam Exp $
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*/
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/*
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*
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* This example shows how to implement a simple code lock. The code
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* lock waits for key presses from a numeric keyboard and if the
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* correct code is entered, the lock is unlocked. There is a maximum
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* time of one second between each key press, and after the correct
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* code has been entered, no more keys must be pressed for 0.5 seconds
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* before the lock is opened.
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*
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* This is an example that shows two things:
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* - how to implement a code lock key input mechanism, and
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* - how to implement a sequential timed routine.
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*
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* The program consists of two protothreads, one that implements the
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* code lock reader and one that implements simulated keyboard input.
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*
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*
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*/
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#ifdef _WIN32
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#include <windows.h>
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#else
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#include <unistd.h>
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#include <sys/time.h>
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#endif
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#include <stdio.h>
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#include "pt.h"
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/*---------------------------------------------------------------------------*/
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/*
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* The following definitions are just for the simple timer library
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* used in this example. The actual implementation of the functions
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* can be found at the end of this file.
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*/
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struct timer { int start, interval; };
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static int timer_expired(struct timer *t);
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static void timer_set(struct timer *t, int usecs);
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/*---------------------------------------------------------------------------*/
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/*
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* This example uses two timers: one for the code lock protothread and
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* one for the simulated key input protothread.
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*/
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static struct timer codelock_timer, input_timer;
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/*---------------------------------------------------------------------------*/
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/*
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* This is the code that has to be entered.
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*/
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static const char code[4] = {'1', '4', '2', '3'};
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/*---------------------------------------------------------------------------*/
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/*
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* This example has two protothread and therefor has two protothread
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* control structures of type struct pt. These are initialized with
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* PT_INIT() in the main() function below.
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*/
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static struct pt codelock_pt, input_pt;
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/*---------------------------------------------------------------------------*/
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/*
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* The following code implements a simple key input. Input is made
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* with the press_key() function, and the function key_pressed()
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* checks if a key has been pressed. The variable "key" holds the
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* latest key that was pressed. The variable "key_pressed_flag" is set
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* when a key is pressed and cleared when a key press is checked.
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*/
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static char key, key_pressed_flag;
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static void
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press_key(char k)
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{
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printf("--- Key '%c' pressed\n", k);
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key = k;
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key_pressed_flag = 1;
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}
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static int
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key_pressed(void)
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{
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if(key_pressed_flag != 0) {
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key_pressed_flag = 0;
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return 1;
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}
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return 0;
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}
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/*---------------------------------------------------------------------------*/
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/*
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* Declaration of the protothread function implementing the code lock
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* logic. The protothread function is declared using the PT_THREAD()
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* macro. The function is declared with the "static" keyword since it
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* is local to this file. The name of the function is codelock_thread
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* and it takes one argument, pt, of the type struct pt.
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*
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*/
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static
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PT_THREAD(codelock_thread(struct pt *pt))
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{
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/* This is a local variable that holds the number of keys that have
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* been pressed. Note that it is declared with the "static" keyword
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* to make sure that the variable is *not* allocated on the stack.
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*/
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static int keys;
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/*
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* Declare the beginning of the protothread.
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*/
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PT_BEGIN(pt);
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/*
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* We'll let the protothread loop until the protothread is
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* expliticly exited with PT_EXIT().
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*/
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while(1) {
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/*
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* We'll be reading key presses until we get the right amount of
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* correct keys.
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*/
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for(keys = 0; keys < sizeof(code); ++keys) {
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/*
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* If we haven't gotten any keypresses, we'll simply wait for one.
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*/
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if(keys == 0) {
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/*
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* The PT_WAIT_UNTIL() function will block until the condition
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* key_pressed() is true.
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*/
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PT_WAIT_UNTIL(pt, key_pressed());
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} else {
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/*
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* If the "key" variable was larger than zero, we have already
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* gotten at least one correct key press. If so, we'll not
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* only wait for the next key, but we'll also set a timer that
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* expires in one second. This gives the person pressing the
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* keys one second to press the next key in the code.
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*/
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timer_set(&codelock_timer, 1000);
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/*
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* The following statement shows how complex blocking
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* conditions can be easily expressed with protothreads and
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* the PT_WAIT_UNTIL() function.
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*/
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PT_WAIT_UNTIL(pt, key_pressed() || timer_expired(&codelock_timer));
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/*
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* If the timer expired, we should break out of the for() loop
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* and start reading keys from the beginning of the while(1)
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* loop instead.
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*/
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if(timer_expired(&codelock_timer)) {
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printf("Code lock timer expired.\n");
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/*
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* Break out from the for() loop and start from the
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* beginning of the while(1) loop.
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*/
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break;
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}
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}
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/*
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* Check if the pressed key was correct.
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*/
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if(key != code[keys]) {
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printf("Incorrect key '%c' found\n", key);
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/*
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* Break out of the for() loop since the key was incorrect.
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*/
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break;
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} else {
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printf("Correct key '%c' found\n", key);
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}
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}
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/*
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* Check if we have gotten all keys.
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*/
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if(keys == sizeof(code)) {
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printf("Correct code entered, waiting for 500 ms before unlocking.\n");
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/*
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* Ok, we got the correct code. But to make sure that the code
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* was not just a fluke of luck by an intruder, but the correct
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* code entered by a person that knows the correct code, we'll
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* wait for half a second before opening the lock. If another
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* key is pressed during this time, we'll assume that it was a
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* fluke of luck that the correct code was entered the first
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* time.
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*/
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timer_set(&codelock_timer, 500);
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PT_WAIT_UNTIL(pt, key_pressed() || timer_expired(&codelock_timer));
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/*
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* If we continued from the PT_WAIT_UNTIL() statement without
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* the timer expired, we don't open the lock.
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*/
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if(!timer_expired(&codelock_timer)) {
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printf("Key pressed during final wait, code lock locked again.\n");
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} else {
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/*
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* If the timer expired, we'll open the lock and exit from the
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* protothread.
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*/
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printf("Code lock unlocked.\n");
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PT_EXIT(pt);
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}
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}
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}
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/*
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* Finally, we'll mark the end of the protothread.
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*/
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PT_END(pt);
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}
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/*---------------------------------------------------------------------------*/
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/*
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* This is the second protothread in this example. It implements a
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* simulated user pressing the keys. This illustrates how a linear
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* sequence of timed instructions can be implemented with
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* protothreads.
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*/
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static
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PT_THREAD(input_thread(struct pt *pt))
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{
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PT_BEGIN(pt);
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printf("Waiting 1 second before entering first key.\n");
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timer_set(&input_timer, 1000);
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PT_WAIT_UNTIL(pt, timer_expired(&input_timer));
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press_key('1');
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timer_set(&input_timer, 100);
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PT_WAIT_UNTIL(pt, timer_expired(&input_timer));
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press_key('2');
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timer_set(&input_timer, 100);
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PT_WAIT_UNTIL(pt, timer_expired(&input_timer));
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press_key('3');
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timer_set(&input_timer, 2000);
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PT_WAIT_UNTIL(pt, timer_expired(&input_timer));
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press_key('1');
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timer_set(&input_timer, 200);
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PT_WAIT_UNTIL(pt, timer_expired(&input_timer));
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press_key('4');
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timer_set(&input_timer, 200);
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PT_WAIT_UNTIL(pt, timer_expired(&input_timer));
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press_key('2');
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timer_set(&input_timer, 2000);
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PT_WAIT_UNTIL(pt, timer_expired(&input_timer));
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press_key('3');
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timer_set(&input_timer, 200);
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PT_WAIT_UNTIL(pt, timer_expired(&input_timer));
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press_key('1');
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timer_set(&input_timer, 200);
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PT_WAIT_UNTIL(pt, timer_expired(&input_timer));
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press_key('4');
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timer_set(&input_timer, 200);
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PT_WAIT_UNTIL(pt, timer_expired(&input_timer));
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press_key('2');
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timer_set(&input_timer, 100);
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PT_WAIT_UNTIL(pt, timer_expired(&input_timer));
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press_key('3');
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timer_set(&input_timer, 100);
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PT_WAIT_UNTIL(pt, timer_expired(&input_timer));
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press_key('4');
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timer_set(&input_timer, 1500);
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PT_WAIT_UNTIL(pt, timer_expired(&input_timer));
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press_key('1');
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timer_set(&input_timer, 300);
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PT_WAIT_UNTIL(pt, timer_expired(&input_timer));
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press_key('4');
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timer_set(&input_timer, 400);
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PT_WAIT_UNTIL(pt, timer_expired(&input_timer));
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press_key('2');
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timer_set(&input_timer, 500);
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PT_WAIT_UNTIL(pt, timer_expired(&input_timer));
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press_key('3');
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timer_set(&input_timer, 2000);
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PT_WAIT_UNTIL(pt, timer_expired(&input_timer));
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PT_END(pt);
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}
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/*---------------------------------------------------------------------------*/
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/*
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* This is the main function. It initializes the two protothread
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* control structures and schedules the two protothreads. The main
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* function returns when the protothread the runs the code lock exits.
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*/
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int
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main(void)
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{
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/*
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* Initialize the two protothread control structures.
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*/
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PT_INIT(&input_pt);
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PT_INIT(&codelock_pt);
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/*
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* Schedule the two protothreads until the codelock_thread() exits.
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*/
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while(PT_SCHEDULE(codelock_thread(&codelock_pt))) {
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PT_SCHEDULE(input_thread(&input_pt));
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/*
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* When running this example on a multitasking system, we must
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* give other processes a chance to run too and therefore we call
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* usleep() resp. Sleep() here. On a dedicated embedded system,
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* we usually do not need to do this.
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*/
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#ifdef _WIN32
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Sleep(0);
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#else
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usleep(10);
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#endif
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}
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return 0;
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}
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/*---------------------------------------------------------------------------*/
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/*
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* Finally, the implementation of the simple timer library follows.
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*/
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#ifdef _WIN32
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static int clock_time(void)
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{ return (int)GetTickCount(); }
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#else /* _WIN32 */
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static int clock_time(void)
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{
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struct timeval tv;
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struct timezone tz;
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gettimeofday(&tv, &tz);
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return tv.tv_sec * 1000 + tv.tv_usec / 1000;
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}
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#endif /* _WIN32 */
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static int timer_expired(struct timer *t)
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{ return (int)(clock_time() - t->start) >= (int)t->interval; }
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static void timer_set(struct timer *t, int interval)
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{ t->interval = interval; t->start = clock_time(); }
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/*---------------------------------------------------------------------------*/
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