cosmopolitan/libc/intrin/dll.c
Jōshin e16a7d8f3b
flip et / noet in modelines
`et` means `expandtab`.

```sh
rg 'vi: .* :vi' -l -0 | \
  xargs -0 sed -i '' 's/vi: \(.*\) et\(.*\)  :vi/vi: \1 xoet\2:vi/'
rg 'vi: .*  :vi' -l -0 | \
  xargs -0 sed -i '' 's/vi: \(.*\)noet\(.*\):vi/vi: \1et\2  :vi/'
rg 'vi: .*  :vi' -l -0 | \
  xargs -0 sed -i '' 's/vi: \(.*\)xoet\(.*\):vi/vi: \1noet\2:vi/'
```
2023-12-07 22:17:11 -05:00

93 lines
3.6 KiB
C

/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
│ vi: set et ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi │
╞══════════════════════════════════════════════════════════════════════════════╡
│ Copyright 2023 Justine Alexandra Roberts Tunney │
│ │
│ Permission to use, copy, modify, and/or distribute this software for │
│ any purpose with or without fee is hereby granted, provided that the │
│ above copyright notice and this permission notice appear in all copies. │
│ │
│ THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL │
│ WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED │
│ WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE │
│ AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL │
│ DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR │
│ PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER │
│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR │
│ PERFORMANCE OF THIS SOFTWARE. │
╚─────────────────────────────────────────────────────────────────────────────*/
#include "libc/intrin/dll.h"
/**
* @fileoverview Doubly Linked List Library
* Based on designs used by Mike Burrows and Linus Torvalds.
*/
/**
* Makes `succ` and its successors come after `elem`.
*
* It's required that `elem` and `succ` aren't part of the same list.
*/
void dll_splice_after(struct Dll *elem, struct Dll *succ) {
struct Dll *tmp1, *tmp2;
tmp1 = elem->next;
tmp2 = succ->prev;
elem->next = succ;
succ->prev = elem;
tmp2->next = tmp1;
tmp1->prev = tmp2;
}
/**
* Removes item from doubly-linked list.
*
* @param list is a doubly-linked list, where `!*list` means empty
*/
void dll_remove(struct Dll **list, struct Dll *elem) {
if (*list == elem) {
if ((*list)->prev == *list) {
*list = 0;
} else {
*list = (*list)->prev;
}
}
elem->next->prev = elem->prev;
elem->prev->next = elem->next;
elem->next = elem;
elem->prev = elem;
}
/**
* Inserts items into list, at the beginning.
*
* The resulting list will start with `elem`, followed by other items in
* `elem`, followed by the items previously in `*list`.
*
* @param list is a doubly-linked list, where `!*list` means empty
* @param elem must not be a member of `list`, or null for no-op
*/
void dll_make_first(struct Dll **list, struct Dll *elem) {
if (elem) {
if (!*list) {
*list = elem->prev;
} else {
dll_splice_after(*list, elem);
}
}
}
/**
* Inserts items into list, at the end.
*
* The resulting `*list` will end with `elem`, preceded by the other
* items in `elem`, preceded by the items previously in `*list`.
*
* @param list is a doubly-linked list, where `!*list` means empty
* @param elem must not be a member of `list`, or null for no-op
*/
void dll_make_last(struct Dll **list, struct Dll *elem) {
if (elem) {
dll_make_first(list, elem->next);
*list = elem;
}
}