//
// ring.gpiolib.c
//
// gpiolib ring oscillator test
//    gcc ring.gpiolib.c -o ring.gpiolib
//
// Neil Gershenfeld 12/19/20
//
// This work may be reproduced, modified, distributed,
// performed, and displayed for any purpose, but must
// acknowledge this project. Copyright is retained and
// must be preserved. The work is provided as is; no
// warranty is provided, and users accept all liability.
//
//
#include <stdio.h>
#include <fcntl.h>
#include <string.h>
#include <linux/gpio.h>
#include <sys/ioctl.h>
int main(int argc,char *argv[]) {
   int gpio;
   struct gpiochip_info chip_info;
   struct gpiohandle_request request_in,request_out;
   struct gpiohandle_data data_in,data_out;
   gpio = open("/dev/gpiochip0",0);
   ioctl(gpio,GPIO_GET_CHIPINFO_IOCTL,&chip_info);
   printf("name: %s, label: %s, lines: %u\n",
      chip_info.name,chip_info.label,chip_info.lines);
   request_out.lineoffsets[0] = 23;
   request_out.lines = 1;
   request_out.flags = GPIOHANDLE_REQUEST_OUTPUT;
   strcpy(request_out.consumer_label,"ring.gpiolib out");
   ioctl(gpio,GPIO_GET_LINEHANDLE_IOCTL,&request_out);
   request_in.lineoffsets[0] = 24;
   request_in.lines = 1;
   request_in.flags = GPIOHANDLE_REQUEST_INPUT;
   strcpy(request_in.consumer_label,"ring.gpiolib in");
   ioctl(gpio,GPIO_GET_LINEHANDLE_IOCTL,&request_in);
   while (1) {
      ioctl(request_in.fd,GPIOHANDLE_GET_LINE_VALUES_IOCTL,&data_in);
      if (data_in.values[0] == 0) {
         data_out.values[0] = 1;
         ioctl(request_out.fd,GPIOHANDLE_SET_LINE_VALUES_IOCTL,&data_out);
         }
      else {
         data_out.values[0] = 0;
         ioctl(request_out.fd,GPIOHANDLE_SET_LINE_VALUES_IOCTL,&data_out);
         }
      }
   }