#pragma once
// ke_list.h - intrusive doubly-linked list
// Used throughout the kernel for run queues, wait lists, thread lists, etc.
#include <stddef.h>

typedef struct LIST_ENTRY {
    struct LIST_ENTRY* Fwd;
    struct LIST_ENTRY* Bwd;
} LIST_ENTRY;

#define LIST_INIT(head)     ((head)->Fwd = (head)->Bwd = (head))
#define LIST_IS_EMPTY(head) ((head)->Fwd == (head))

// Recover the containing struct pointer from an embedded LIST_ENTRY.
#define CONTAINING_RECORD(ptr, type, member) \
    ((type *)((char *)(ptr) - offsetof(type, member)))

static inline void ListInsertTail(LIST_ENTRY* head, LIST_ENTRY* node) {
    node->Bwd      = head->Bwd;
    node->Fwd      = head;
    head->Bwd->Fwd = node;
    head->Bwd      = node;
}

static inline void ListInsertHead(LIST_ENTRY* head, LIST_ENTRY* node) {
    node->Fwd      = head->Fwd;
    node->Bwd      = head;
    head->Fwd->Bwd = node;
    head->Fwd      = node;
}

static inline void ListRemove(LIST_ENTRY* node) {
    node->Bwd->Fwd = node->Fwd;
    node->Fwd->Bwd = node->Bwd;
    node->Fwd = node->Bwd = node;   /* self-loop: poison against double-remove */
}

// Pop the first entry off the list, or NULL if empty.
static inline LIST_ENTRY* ListPopHead(LIST_ENTRY* head) {
    if (LIST_IS_EMPTY(head)) return (LIST_ENTRY *)0;
    LIST_ENTRY* node = head->Fwd;
    ListRemove(node);
    return node;
}