//Inculde Header Files-----------------------------------------------
#include<stdlib.h>
#include<stdio.h>
#include<errno.h>
#include<sys/time.h>
#include<unistd.h>
#include<termios.h>
#include<sys/types.h>
#include<sys/stat.h>
#include<fcntl.h>
#include<sys/resource.h>
#include<pthread.h>
#include<signal.h>

//Enumerations-------------------------------------------------------
typedef enum {false, true} bool; 
typedef enum {fuse_read,
		      fuse_write,
		      page_read,
		  	  page_write,
		  	  prog_check} mode;

//Constants----------------------------------------------------------
#define nibble_lo 0x0F
#define nibble_hi 0xF0
#define frame_mask 0x90
#define page_size 64

//Structs------------------------------------------------------------
typedef struct {
	char mode;
	char opt_lo;
	char opt_hi;
} cmd_t;

//Makros-------------------------------------------------------------
#define error_handler(err_no, err_str) 	\
					errno = err_no;		\
					perror(err_str);	\
					exit(EXIT_FAILURE);

//Protoypes----------------------------------------------------------
void * signal_thread(void * arg_ptr);
void set_timer(int sec, int usec);
char * cmd_build(mode cmd_mode, char cmd_option);
char * page_build(char size);
char * page_mask(char * page_build_ptr);
char * page_get(FILE * input_stream);

//Variables----------------------------------------------------------
char cmd_arr[3];
bool timer_state;
char page_buf[64];

//+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
//Signal Thread
void * signal_thread(void * arg_ptr){
	sigset_t * signal_ptr = (sigset_t *)arg_ptr;
	int signal_nr, signal_err;
	signal_err = sigwait(signal_ptr, &signal_nr);
	if(signal_err!=0){
		error_handler(signal_err, "Problem with Signal");
	}
	else if(signal_nr!=SIGALRM){
		fprintf(stderr, "Wrong Signal \n");
	}
	timer_state = false;
	return NULL;
}

//+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
//Set Timer
void set_timer(int sec, int usec){
	struct itimerval timer;
	int timer_err, signal_err;
	timer.it_interval.tv_sec = sec;
	timer.it_interval.tv_usec = usec;
	timer.it_value.tv_sec = sec;
	timer.it_value.tv_usec = usec;
	timer_err = setitimer(ITIMER_REAL, &timer, NULL);
	if(timer_err!=0){
		error_handler(timer_err, "Error setting Timer");
	}
	timer_state = true;
}

//+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
//Build Command
char * cmd_build(mode cmd_mode, char cmd_option){
	cmd_t * cmd_ptr = (cmd_t *)malloc(sizeof(cmd_t));
	(*cmd_ptr).mode = frame_mask|cmd_mode;
	(*cmd_ptr).opt_lo = frame_mask|(cmd_option&nibble_lo);
	(*cmd_ptr).opt_hi = frame_mask|((cmd_option>>4)&nibble_lo);
	char * frame_ptr = &((*cmd_ptr).mode);
	return frame_ptr;
}

//+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
//Build Page
char * page_build(char size){
	char page[size];
	for(int i=0; i<size; i++){
		page[i] = 0xFF;
	}
	char * page_ptr = &page[0];
	return page_ptr;
}

//++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
//Mask Page
char * page_mask(char * page_build_ptr){
	char page[2*page_size];
	char * page_mask_ptr = &page[0];
	for(int i=0; i<page_size; i++){
		*page_mask_ptr = frame_mask|(*page_build_ptr&nibble_lo);
		*(page_mask_ptr+1) = frame_mask|
									((*page_build_ptr&nibble_hi)>>4);
		page_mask_ptr = page_mask_ptr + 2;
	}
	page_mask_ptr = &page[0];
	return page_mask_ptr;
}

//++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
//Get Page
char * page_get(FILE * input_stream){
	int count = 7;
	char * page_buf_ptr = (char*)malloc(page_size*sizeof(char));
	for(int i=0; i<page_size; ){
		*page_buf_ptr = fgetc(input_stream);
		*(page_buf_ptr+1) = fgetc(input_stream);
		if(count>6){
			if(*page_buf_ptr==0x3A){
				count=0;
			}
			else{
				for(int j=0; j<2; j++){
					if(*(page_buf_ptr+j)<0x39){
						*(page_buf_ptr+j)=*(page_buf_ptr+j)-0x30;
					}
					else{
						*(page_buf_ptr+j)=*(page_buf_ptr+j)-0x37;
					}
				}
				*page_buf_ptr = ((*page_buf_ptr<<4)&nibble_hi)|
									((*page_buf_ptr+1)&nibble_lo);
				i++;
				page_buf_ptr++;
			}
		}
		else{
			count++;
		}
	}
	return page_buf_ptr-page_size;
}