#include<stdlib.h>

#include<stdio.h>

#include<string.h>

#include<unistd.h>

#include<fcntl.h>

#include<poll.h>

#define MSG(args...) printf(args) 

//函数声明

static int gpio_export(int pin);

static int gpio_unexport(int pin);

static int gpio_direction(int pin, int dir);

static int gpio_write(int pin, int value);

static int gpio_read(int pin);

static int gpio_edge(int pin, int edge);

static int gpio_export(int pin)

{

    char buffer[64];

    int len;

    int fd;  

    fd = open("/sys/class/gpio/export", O_WRONLY);

    if (fd < 0)

    {

        MSG("Failed to open export for writing!\n");

        return(-1);

    }  

    len = snprintf(buffer, sizeof(buffer), "%d", pin);

    printf("%s,%d,%d\n",buffer,sizeof(buffer),len);

    if (write(fd, buffer, len) < 0)

    {

        MSG("Failed to export gpio!");

        return -1;

    }  

    close(fd);

    return 0;

}

static int gpio_unexport(int pin)

{

    char buffer[64];

    int len;

    int fd;  

    fd = open("/sys/class/gpio/unexport", O_WRONLY);

    if (fd < 0)

    {

        MSG("Failed to open unexport for writing!\n");

        return -1;

    }  

    len = snprintf(buffer, sizeof(buffer), "%d", pin);

    if (write(fd, buffer, len) < 0)

    {

        MSG("Failed to unexport gpio!");

        return -1;

    }  

    close(fd);

    return 0;

}

//dir: 0-->IN, 1-->OUT

static int gpio_direction(int pin, int dir)

{

    static const char dir_str[] = "in\0out";

    char path[64];

    int fd;  

    snprintf(path, sizeof(path), "/sys/class/gpio/gpio%d/direction", pin);

    fd = open(path, O_WRONLY);

    if (fd < 0)

    {

        MSG("Failed to open gpio direction for writing!\n");

        return -1;

    }  

    if (write(fd, &dir_str[dir == 0 ? 0 : 3], dir == 0 ? 2 : 3) < 0)

    {

        MSG("Failed to set direction!\n");

        return -1;

    }  

    close(fd);

    return 0;

}

//value: 0-->LOW, 1-->HIGH

static int gpio_write(int pin, int value)

{

    static const char values_str[] = "01";

    char path[64];

    int fd;  

    snprintf(path, sizeof(path), "/sys/class/gpio/gpio%d/value", pin);

    fd = open(path, O_WRONLY);

    if (fd < 0)

    {

        MSG("Failed to open gpio value for writing!\n");

        return -1;

    }  

    if (write(fd, &values_str[value == 0 ? 0 : 1], 1) < 0)

    {

        MSG("Failed to write value!\n");

        return -1;

    }  

    close(fd);

    return 0;

}

static int gpio_read(int pin)

{

    char path[64];

    char value_str[3];

    int fd;  

    snprintf(path, sizeof(path), "/sys/class/gpio/gpio%d/value", pin);

    fd = open(path, O_RDONLY);

    if (fd < 0)

    {

        MSG("Failed to open gpio value for reading!\n");

        return -1;

    }  

    if (read(fd, value_str, 3) < 0)

    {

        MSG("Failed to read value!\n");

        return -1;

    }  

    close(fd);

    return (atoi(value_str));

}

// none表示引脚为输入，不是中断引脚

// rising表示引脚为中断输入，上升沿触发

// falling表示引脚为中断输入，下降沿触发

// both表示引脚为中断输入，边沿触发

// 0-->none, 1-->rising, 2-->falling, 3-->both

static int gpio_edge(int pin, int edge)

{

const char dir_str[] = "none\0rising\0falling\0both";

char ptr;

char path[64];

    int fd;

switch(edge)

{

    case 0:

        ptr = 0;

        break;

    case 1:

        ptr = 5;

        break;

    case 2:

        ptr = 12;

        break;

    case 3:

        ptr = 20;

        break;

    default:

        ptr = 0;

} 

    snprintf(path, sizeof(path), "/sys/class/gpio/gpio%d/edge", pin);

    fd = open(path, O_WRONLY);

    if (fd < 0)

    {

        MSG("Failed to open gpio edge for writing!\n");

        return -1;

    }  

    if (write(fd, &dir_str[ptr], strlen(&dir_str[ptr])) < 0)

    {

        MSG("Failed to set edge!\n");

        return -1;

    }  

    close(fd);

    return 0;

}

//GPIO1_17

int main()

{

    int gpio_fd, ret;

    struct pollfd fds[1];

    char buff[10];

    unsigned char cnt = 0;

    gpio_unexport(44);

    gpio_unexport(45);

    //p8_12 init

    gpio_export(44);

    gpio_direction(44, 1);//output out

    gpio_write(44, 1);

    //p8_11 init

    gpio_export(45);

    gpio_direction(45, 0);//input in

    gpio_edge(45,2);

    gpio_fd = open("/sys/class/gpio/gpio45/value",O_RDONLY);

    if(gpio_fd < 0)

    {

        MSG("Failed to open value!\n");

        return -1;

    }

    fds[0].fd = gpio_fd;

    fds[0].events  = POLLPRI;

    while(1)

    {

        ret = read(gpio_fd,buff,10);

        if( ret == -1 )

        MSG("read\n");

        ret = poll(fds,1,0);

        if( ret == -1 )

        MSG("poll\n");

        if( fds[0].revents & POLLPRI)

        {

            ret = lseek(gpio_fd,0,SEEK_SET);

            if( ret == -1 )

            MSG("lseek\n");

            //gpio_write(44, cnt++%2);

            printf("**********************************\n");

        }

        usleep(5);

    }

    return 0;

}