doubly linked list

#include <stdio.h>
#include <stdlib.h>
#include <math.h>

struct nodeD{
    int data;
    struct nodeD* next;
    struct nodeD* prev;
};

struct nodeD* makeEmpty(struct nodeD* L);
void insertAtFirst(int data_, struct nodeD* L);
void insertAfterPosition(int x,struct nodeD* P, struct nodeD* L);
struct nodeD* findPrevious(int x,struct nodeD* L);
int isLast(struct nodeD* P , struct nodeD* L);
void delete(int x, struct nodeD* L);
struct nodeD* find(int x, struct nodeD* L);
void printList(struct nodeD* L);
void reverse(struct nodeD* L);


int main(){

    struct nodeD* head1 = NULL;
    head1 = makeEmpty(head1);
    insertAtFirst(1,head1);
    insertAtFirst(2,head1);
    insertAtFirst(3,head1);
    insertAtFirst(4,head1);
    insertAtFirst(5,head1);
    insertAtFirst(6,head1);
    printList(head1);
    reverse(head1);
    printList(head1);


    return 0;
}


struct nodeD* makeEmpty(struct nodeD* L){
    L = malloc(sizeof(struct nodeD));
    L->next = NULL;
    L->prev = NULL;

    return L;
}


void insertAtFirst(int data_, struct nodeD* L){
    struct nodeD* newNode = malloc(sizeof(struct nodeD));
    newNode->data = data_;
    newNode->next = L->next;
    newNode->prev = L;
     L->next = newNode;
    L->next->prev = newNode;


}

void insertAfterPosition(int x,struct nodeD* P, struct nodeD* L){
    struct nodeD* newNode = malloc(sizeof(struct nodeD));

    newNode->data = x;
    newNode->next = P->next;
    newNode->prev = P;
    P->next->prev = newNode;
    P->next = newNode;

}

struct nodeD* findPrevious(int x,struct nodeD* L){

    struct nodeD* p = L;

    while(p->next->data!=x && p->next!=NULL){
        p = p->next;
    }

    return p;

}

int isLast(struct nodeD* P , struct nodeD* L){
    return P->next == NULL ;
}


void delete(int x, struct nodeD* L){
    struct nodeD* p = findPrevious(x,L);

    if(!isLast(p,L)){
        struct nodeD* temp= p->next;
        temp->next->prev = p;
        p->next = temp->next;
        temp->prev = NULL;
        temp->next = NULL;
        free(temp);
    }
}


struct nodeD* find(int x, struct nodeD* L){
    struct nodeD* p = L;
    p = p->next;

    while(p->data!=x && p!=NULL){
            p = p->next;
    }

    return p;
}


void printList(struct nodeD* L){
    struct nodeD* p = L->next;

    while(p!=NULL){
        printf("%d   ",p->data);
        p = p->next;
    }

    printf(" \n");
}



void reverse(struct nodeD* L){
    struct nodeD* curr  = L->next;
    struct nodeD* prev = NULL;
    struct nodeD* nxt  = curr->next;


    while(curr!=NULL){
        curr->next = prev;
        curr->prev = nxt;
        prev = curr;
        curr = nxt;

        if(nxt!=NULL)
            nxt = nxt->next;
    }

    L->next = prev;
    prev->prev = L;

    printList(L);
}