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#include <stdio.h>
#include <stdlib.h>
#include <stddef.h>
#include <unistd.h>
#include <stdint.h>
#include <stdbool.h>
#include <string.h>
// circular doubly linked list demo
struct waster {
int gg;
struct waster *prev;
struct waster *next;
};
struct waster *newnode (void) {
struct waster *new = malloc(sizeof(struct waster));
return new;
}
struct waster *llist (uint64_t count) {
struct waster *wr1 = malloc(sizeof(struct waster));
struct waster *head = wr1;
wr1->gg = 0; // Data for first node
wr1->prev = NULL; // There is no previous node *yet*
wr1->next = newnode(); // Make new node, next points to it
struct waster *prv = wr1; // Make prv point to current node
wr1 = wr1->next; // Make wr1 point to next node
for (uint64_t i = 1 ; i < count ; i++) { // Actual loop starts
wr1->gg = i; // Data for 2nd node
wr1->prev = prv; // make prev point to prv = wr1 = last node
if (i == count-1) {
wr1->next = head;
head->prev = wr1;
} else {
wr1->next = newnode(); // Make next node, next points to it
}
prv = wr1; // prv points to current node
wr1 = wr1->next; // Make wr1 point to the next node
}
return head;
}
void freellist(struct waster *wr1) {
struct waster *head = wr1;
struct waster *save;
while (wr1->next != head) {
save = wr1;
wr1 = wr1->next;
free(save);
}
}
int main (void) {
uint64_t passes = 4;
uint64_t passstep = 1;
uint64_t steps = 20;
struct waster *wr1 = llist(steps);
struct waster *p;
while(passstep < passes+1) {
uint64_t steps_count = 0;
for (p = wr1 ; steps_count < steps ; p = p->next, steps_count++) {
void *prev = (void*)p->prev;
void *next = (void*)p->next;
printf("\n------%p----------",(void *)p);
printf("\ndata: %d\nprev: %p\nnext: %p\n", p->gg, prev, next);
printf("-----------------------------\n");
}
printf("\npass %lld done\n", passstep);
passstep = passstep+1;
}
printf("\nHEAD: %p\n", (void*)wr1);
freellist(wr1);
return 0;
}
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