mirror of
https://github.com/jart/cosmopolitan.git
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0a24b4fc3c
The *NSYNC linked list API is good enough that it deserves to be part of the C libray, so this change writes an improved version of it which uses that offsetof() trick from the Linux Kernel. We vendor all of the *NSYNC tests in third_party which helped confirm the needed refactoring is safe This change also deletes more old code that didn't pan out. My goal here is to work towards a vision where the Cosmopolitan core libraries become less experimental and more focused on curation. This better reflects the current level of quality we've managed to achieve.
93 lines
3.6 KiB
C
93 lines
3.6 KiB
C
/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
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│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi│
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╞══════════════════════════════════════════════════════════════════════════════╡
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│ Copyright 2023 Justine Alexandra Roberts Tunney │
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│ │
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│ Permission to use, copy, modify, and/or distribute this software for │
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│ any purpose with or without fee is hereby granted, provided that the │
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│ above copyright notice and this permission notice appear in all copies. │
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│ │
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│ THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL │
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│ WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED │
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│ WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE │
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│ AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL │
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│ DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR │
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│ PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER │
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│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR │
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│ PERFORMANCE OF THIS SOFTWARE. │
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╚─────────────────────────────────────────────────────────────────────────────*/
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#include "libc/intrin/dll.h"
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/**
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* @fileoverview Doubly Linked List Library
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* Based on designs used by Mike Burrows and Linus Torvalds.
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*/
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/**
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* Makes `succ` and its successors come after `elem`.
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*
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* It's required that `elem` and `succ` aren't part of the same list.
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*/
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void dll_splice_after(struct Dll *elem, struct Dll *succ) {
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struct Dll *tmp1, *tmp2;
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tmp1 = elem->next;
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tmp2 = succ->prev;
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elem->next = succ;
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succ->prev = elem;
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tmp2->next = tmp1;
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tmp1->prev = tmp2;
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}
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/**
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* Removes item from doubly-linked list.
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*
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* @param list is a doubly-linked list, where `!*list` means empty
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*/
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void dll_remove(struct Dll **list, struct Dll *elem) {
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if (*list == elem) {
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if ((*list)->prev == *list) {
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*list = 0;
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} else {
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*list = (*list)->prev;
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}
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}
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elem->next->prev = elem->prev;
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elem->prev->next = elem->next;
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elem->next = elem;
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elem->prev = elem;
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}
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/**
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* Inserts items into list, at the beginning.
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*
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* The resulting list will start with `elem`, followed by other items in
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* `elem`, followed by the items previously in `*list`.
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*
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* @param list is a doubly-linked list, where `!*list` means empty
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* @param elem must not be a member of `list`, or null for no-op
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*/
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void dll_make_first(struct Dll **list, struct Dll *elem) {
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if (elem) {
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if (!*list) {
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*list = elem->prev;
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} else {
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dll_splice_after(*list, elem);
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}
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}
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}
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/**
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* Inserts items into list, at the end.
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*
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* The resulting `*list` will end with `elem`, preceded by the other
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* items in `elem`, preceded by the items previously in `*list`.
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*
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* @param list is a doubly-linked list, where `!*list` means empty
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* @param elem must not be a member of `list`, or null for no-op
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*/
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void dll_make_last(struct Dll **list, struct Dll *elem) {
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if (elem) {
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dll_make_first(list, elem->next);
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*list = elem;
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}
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}
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