168 lines
3.9 KiB
C++
168 lines
3.9 KiB
C++
/*
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* https://github.com/mrshu/GPIOlib
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* Copyright (c) 2011, Copyright (c) 2011 mr.Shu
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* All rights reserved.
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*
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* Modified on 24 June 2012, 11:06 AM
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* File: gpio.cpp
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* Author: purinda (purinda@gmail.com)
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*
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* Patched for filedescriptor catching and error control by L Diaz 2018
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*/
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#include "gpio.h"
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#include <stdlib.h>
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#include <unistd.h>
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#include <fcntl.h>
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#include <sys/types.h>
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#include <sys/stat.h>
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std::map<int, GPIOfdCache_t> GPIO::cache;
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GPIO::GPIO()
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{
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}
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GPIO::~GPIO()
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{
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}
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void GPIO::open(int port, int DDR)
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{
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FILE* f;
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f = fopen("/sys/class/gpio/export", "w");
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if (f == NULL) {
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throw GPIOException("can't export GPIO pin .check access rights");
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}
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fprintf(f, "%d\n", port);
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fclose(f);
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int counter = 0;
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char file[128];
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sprintf(file, "/sys/class/gpio/gpio%d/direction", port);
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while ((f = fopen(file, "w")) == NULL) { //Wait 10 seconds for the file to be accessible if not open on first attempt
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sleep(1);
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counter++;
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if (counter > 10) {
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throw GPIOException("can't access /sys/class/gpio/gpio%d/direction GPIO pin. check access rights");
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/*perror("Could not open /sys/class/gpio/gpio%d/direction");
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exit(0); */
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}
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}
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int l = (DDR == 0) ? fprintf(f, "in\n") : fprintf(f, "out\n");
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if (!(l == 3 || l == 4)) {
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fclose(f);
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throw GPIOException("can't set direction on GPIO pin. check access rights");
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}
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/*
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if (DDR == 0)
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fprintf(f, "in\n");
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else printf(f, "out\n");
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*/
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fclose(f);
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// Caches the GPIO descriptor;
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sprintf(file, "/sys/class/gpio/gpio%d/value", port);
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int flags = (DDR == 0) ? O_RDONLY : O_WRONLY;
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int fd = ::open(file, flags);
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if (fd < 0) {
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throw GPIOException("Can't open the GPIO");
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} else {
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cache[port] = fd; // cache the fd;
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lseek(fd, SEEK_SET, 0);
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}
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}
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void GPIO::close(int port)
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{
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std::map<int, GPIOfdCache_t>::iterator i;
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i = cache.find(port);
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if (i != cache.end()) {
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close(i->second); // close the cached fd
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cache.erase(i); // Delete cache entry
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}
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// Do unexport
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FILE* f;
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f = fopen("/sys/class/gpio/unexport", "w");
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if (f != NULL) {
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fprintf(f, "%d\n", port);
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fclose(f);
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}
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}
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int GPIO::read(int port)
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{
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std::map<int, GPIOfdCache_t>::iterator i;
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int fd;
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i = cache.find(port);
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if (i == cache.end()) { // Fallback to open the gpio
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GPIO::open(port, GPIO::DIRECTION_IN);
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i = cache.find(port);
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if (i == cache.end()) {
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throw GPIOException("can't access to GPIO");
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} else {
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fd = i->second;
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}
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} else {
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fd = i->second;
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}
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char c;
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if (lseek(fd, 0, SEEK_SET) == 0 && ::read(fd, &c, 1) == 1) {
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return (c == '0') ? 0 : 1;
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} else {
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throw GPIOException("can't access to GPIO");
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}
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/*FILE *f;
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char file[128];
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sprintf(file, "/sys/class/gpio/gpio%d/value", port);
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f = fopen(file, "r");
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int i;
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fscanf(f, "%d", &i);
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fclose(f);
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return i;
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*/
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}
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void GPIO::write(int port, int value)
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{
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std::map<int, GPIOfdCache_t>::iterator i;
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int fd;
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i = cache.find(port);
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if (i == cache.end()) { // Fallback to open the gpio
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GPIO::open(port, GPIO::DIRECTION_OUT);
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i = cache.find(port);
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if (i == cache.end()) {
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throw GPIOException("can't access to GPIO");
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} else {
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fd = i->second;
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}
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} else {
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fd = i->second;
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}
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if (lseek(fd, 0, SEEK_SET) != 0) {
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throw GPIOException("can't access to GPIO");
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}
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int l = (value == 0) ? ::write(fd, "0\n", 2) : ::write(fd, "1\n", 2);
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if (l != 2) {
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throw GPIOException("can't access to GPIO");
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}
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/*FILE *f;
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char file[128];
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sprintf(file, "/sys/class/gpio/gpio%d/value", port);
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f = fopen(file, "w");
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if (value == 0) fprintf(f, "0\n");
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else fprintf(f, "1\n");
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fclose(f);*/
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}
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