could I got some help to edit this code please
Hey guys, my name is JUSTIN and this is my first thread here :)
I want to edit Fibonacci program which do this equation
Fib(n) = 1 if n is 0 or 1
=Fib(n-1) + Fib(n-2) otherwise
and make it work for this one:
f(n) = 1 if n=1,2,3
= f(n-1)*f(n-2)+f(n-3), when n>3
the code is attached and its here also:
Code:
/* fibonacci program written by ian a. mason @ u.n.e easter '97 */
/* touched up easter '98 */
/* and again march '99 */
/* and again august '01 */
/* and again august '02 */
/* and again august '04 */
#include <stdio.h> /* for fprintf */
#include <stdlib.h> /* for exit */
#include <unistd.h> /* for fork */
#include <string.h> /* for strtok */
#define BUFFSIZE 50
int parse_args(int argc, char *argv[ ], int *np){
if ( (argc != 2) || ((*np = atoi (argv[1])) <= 0) ) {
fprintf (stderr, "Usage: %s nprocs\n", argv[0]);
return(-1); };
return(0);
}
int make_trivial_ring(){
int fd[2];
if (pipe (fd) == -1)
return(-1);
if ((dup2(fd[0], STDIN_FILENO) == -1) ||
(dup2(fd[1], STDOUT_FILENO) == -1))
return(-2);
if ((close(fd[0]) == -1) || (close(fd[1]) == -1))
return(-3);
return(0);
}
int add_new_node(int *pid){
int fd[2];
if (pipe(fd) == -1)
return(-1);
if ((*pid = fork()) == -1)
return(-2);
if(*pid > 0 && dup2(fd[1], STDOUT_FILENO) < 0)
return(-3);
if (*pid == 0 && dup2(fd[0], STDIN_FILENO) < 0)
return(-4);
if ((close(fd[0]) == -1) || (close(fd[1]) == -1))
return(-5);
return(0);
}
void get_integers(char buff[], long *first, long *second){
char* token = NULL;
if((first == NULL) || (second == NULL)) return;
if(read(STDIN_FILENO, buff, BUFFSIZE) > 0){
*first = atol((((token = strtok(buff," ")) == NULL) ? "0" : token));
*second = atol((((token = strtok(NULL," ")) == NULL) ? "0" : token));
} else {
*first = 0;
*second = 0;
}
}
void safe_sum(long first, long *second, long *third){
if((second == NULL) || third == NULL) return;
*third = first + *second;
if(*third < 0){
fprintf(stderr,
"Overflow detected: %ld + %ld != %ld\n",
first, *second, *third);
*third = 0;
*second = 0; };
}
int send_numbers(char buff[], long num1, long num2){
int bytes, len;
sprintf(buff, "%ld %ld", num1, num2);
len = strlen(buff) + 1;
if((bytes = write(STDOUT_FILENO, buff, len)) != len){
fprintf(stderr,
"Write of %d bytes failed, only sent %d bytes\n",
len, bytes);
return -1;
} else {
return bytes;
}
}
void report_sum(int i, long first, long old_second, long second, long third){
fprintf(stderr,
"\nProcess %d with PID %d and parent PID %d recieved %ld %ld and sent %ld %ld.\n",
i, (int)getpid(), (int)getppid(), first, old_second, second, third);
}
int main(int argc, char *argv[]){
int i; /* number of this process (starting with 1) */
int childpid; /* indicates process should spawn another */
int nprocs; /* total number of processes in ring */
char buff[BUFFSIZE]; /* string for integers */
long first; /* first integer in fibonacci computation */
long second; /* second integer in fibonacci computation */
long third ; /* sum of first and second */
if(parse_args(argc,argv,&nprocs) < 0) exit(EXIT_FAILURE);
if(make_trivial_ring() < 0){
perror("Could not make trivial ring");
exit(EXIT_FAILURE); };
for (i = 1; i < nprocs; i++) {
if(add_new_node(&childpid) < 0){
perror("Could not add new node to ring");
exit(EXIT_FAILURE); };
if (childpid) break; };
{
/* ring process code */
long old_second;
if(i == 1){
/* mother of all processes */
send_numbers(buff, 1,1); }
/* all processes */
get_integers(buff, &first, &second);
old_second = second;
safe_sum(first,&second,&third);
if(i > 1){
send_numbers(buff, second, third);
report_sum( i, first, old_second, second, third); }
else {
fprintf(stderr,"\n\nfibonacci(%d) = %ld\n\n", nprocs, second); }
exit(EXIT_SUCCESS);
}
} /* end of main program here */
cheeers :)
