// Gerardo Marx 24/09/2026
// gpio command tool
// eg. ./gpio 17 out 1
//	   ./gpio 17 in 
//	   ./gpio 17 blink 500(ms)


#include <stdio.h>
#include <fcntl.h>
#include <unistd.h>
#include <string.h>

// prototype functions
int gpio_export(const char *gpio);
int gpio_direction(const char *gpio, const char *direction); // this function
int gpio_write(int gpio, int value);

int main(int argc, char *argv[]){

	int fd;
	const char *pin = argv[1]; // get gpio number from argument
	const char *dir = argv[2]; // get gpio direction from arguments
							   //
	gpio_export(pin); 
	gpio_direction(pin, dir);
	
	
	// pin value to 1
	fd = open("/sys/class/gpio/chip0/gpio17/value", O_WRONLY);
	if(fd<0)
	{
		perror("Error opening the GPIO path");
		return -1;
	}
	write(fd,"1",1);
	close(fd);
	sleep(1);
	// pin valu to 0
	fd = open("/sys/class/gpio/chip0/gpio17/value", O_WRONLY);
	if(fd<0)
	{
		perror("Error opening the GPIO path");
		return -1;
	}
	write(fd,"0",1);
	close(fd);
	sleep(1);
	// unexport
	fd = open("/sys/class/gpio/chip0/unexport", O_WRONLY);
	if(fd<0)
	{
		perror("Error opening the GPIO path");
		return -1;
	}
	write(fd,"17",2);
	close(fd);


	printf("Hello from Raspberry Pi!\n");
	printf("Number of arguments: %d\n", argc);
	printf("Program is reciving: %s\n", argv[0]);

	if(argc > 1 )
		printf("Argument: %s\n", argv[1]);
	return 0;
}

// comple functions
//
// gpio_export
int gpio_export(const char *gpio){
	int fd;
	fd = open("/sys/class/gpio/chip0/export", O_WRONLY);
	if(fd<0){
		perror("Error opening the GPIO path");
		return -1;
	}
	write(fd,gpio,strlen(gpio));
	close(fd);
	return 0;
}

// gpio direction

int gpio_direction(const char *gpio, const char *direction){
	// pin direction - convert into functions
	int fd;
	char path[64];
	snprintf(path, sizeof(path),
			"/sys/class/gpio/chip0/gpio%s/direction", gpio);
	fd = open(path, O_WRONLY); //gpio number
	if(fd<0)
	{
		perror("Error opening the GPIO path");
		return -1;
	}
	write(fd,direction,strlen(direction));
	close(fd);
	return 0;
}