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274 lines
8.5 KiB
C
274 lines
8.5 KiB
C
/*-*- mode:c;indent-tabs-mode:t;c-basic-offset:8;tab-width:8;coding:utf-8 -*-│
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│vi: set et ft=c ts=8 tw=8 fenc=utf-8 :vi│
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╞══════════════════════════════════════════════════════════════════════════════╡
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│ Copyright (c) 1991, 1993 │
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│ The Regents of the University of California. All rights reserved. │
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│ │
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│ Redistribution and use in source and binary forms, with or without │
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│ modification, are permitted provided that the following conditions │
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│ are met: │
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│ 1. Redistributions of source code must retain the above copyright │
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│ notice, this list of conditions and the following disclaimer. │
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│ 2. Redistributions in binary form must reproduce the above copyright │
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│ notice, this list of conditions and the following disclaimer in the │
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│ documentation and/or other materials provided with the distribution. │
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│ 3. Neither the name of the University nor the names of its contributors │
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│ may be used to endorse or promote products derived from this software │
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│ without specific prior written permission. │
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│ │
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│ THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND │
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│ ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE │
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│ IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE │
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│ ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE │
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│ FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL │
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│ DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS │
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│ OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) │
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│ HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT │
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│ LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY │
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│ OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF │
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│ SUCH DAMAGE. │
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╚─────────────────────────────────────────────────────────────────────────────*/
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#include "libc/macros.internal.h"
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#include "libc/mem/alg.h"
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#include "libc/str/str.h"
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// clang-format off
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asm(".ident\t\"\\n\\n\
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OpenBSD Sorting (BSD-3)\\n\
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Copyright 1993 The Regents of the University of California\"");
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asm(".include \"libc/disclaimer.inc\"");
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#define SWAPTYPE_BYTEV 1
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#define SWAPTYPE_INTV 2
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#define SWAPTYPE_LONGV 3
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#define SWAPTYPE_INT 4
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#define SWAPTYPE_LONG 5
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#define CMPPAR int (*cmp)(const void *, const void *, void *),void *arg
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#define CMPARG cmp, arg
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#define CMP(a, b) cmp(a, b, arg)
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#define min(a, b) (a) < (b) ? a : b
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static inline char *med3(char *, char *, char *, CMPPAR);
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static inline void swapfunc(char *, char *, size_t, int);
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#define TYPE_ALIGNED(TYPE, a, es) \
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(((char *)a - (char *)0) % sizeof(TYPE) == 0 && es % sizeof(TYPE) == 0)
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#define swapcode(TYPE, parmi, parmj, n) { \
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size_t i = (n) / sizeof (TYPE); \
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TYPE *pi = (TYPE *) (parmi); \
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TYPE *pj = (TYPE *) (parmj); \
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do { \
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TYPE t = *pi; \
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*pi++ = *pj; \
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*pj++ = t; \
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} while (--i > 0); \
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}
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static inline void
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swapfunc(char *a, char *b, size_t n, int swaptype)
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{
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switch (swaptype) {
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case SWAPTYPE_INT:
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case SWAPTYPE_INTV:
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swapcode(int, a, b, n);
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break;
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case SWAPTYPE_LONG:
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case SWAPTYPE_LONGV:
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swapcode(long, a, b, n);
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break;
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default:
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swapcode(char, a, b, n);
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break;
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}
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}
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#define swap(a, b) do { \
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switch (swaptype) { \
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case SWAPTYPE_INT: { \
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int t = *(int *)(a); \
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*(int *)(a) = *(int *)(b); \
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*(int *)(b) = t; \
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break; \
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} \
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case SWAPTYPE_LONG: { \
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long t = *(long *)(a); \
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*(long *)(a) = *(long *)(b); \
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*(long *)(b) = t; \
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break; \
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} \
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default: \
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swapfunc(a, b, es, swaptype); \
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} \
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} while (0)
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#define vecswap(a, b, n) if ((n) > 0) swapfunc(a, b, n, swaptype)
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static inline char *
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med3(char *a, char *b, char *c, CMPPAR)
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{
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return CMP(a, b) < 0 ?
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(CMP(b, c) < 0 ? b : (CMP(a, c) < 0 ? c : a ))
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:(CMP(b, c) > 0 ? b : (CMP(a, c) < 0 ? a : c ));
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}
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static void
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introsort(char *a, size_t n, size_t es, size_t maxdepth, int swaptype, CMPPAR)
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{
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char *pa, *pb, *pc, *pd, *pl, *pm, *pn;
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int cmp_result;
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size_t r, s;
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loop: if (n < 7) {
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for (pm = a + es; pm < a + n * es; pm += es)
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for (pl = pm; pl > a && CMP(pl - es, pl) > 0;
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pl -= es)
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swap(pl, pl - es);
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return;
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}
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if (maxdepth == 0) {
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if (heapsort_r(a, n, es, CMPARG) == 0)
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return;
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}
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maxdepth--;
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pm = a + (n / 2) * es;
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if (n > 7) {
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pl = a;
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pn = a + (n - 1) * es;
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if (n > 40) {
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s = (n / 8) * es;
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pl = med3(pl, pl + s, pl + 2 * s, CMPARG);
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pm = med3(pm - s, pm, pm + s, CMPARG);
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pn = med3(pn - 2 * s, pn - s, pn, CMPARG);
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}
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pm = med3(pl, pm, pn, CMPARG);
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}
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swap(a, pm);
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pa = pb = a + es;
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pc = pd = a + (n - 1) * es;
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for (;;) {
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while (pb <= pc && (cmp_result = CMP(pb, a)) <= 0) {
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if (cmp_result == 0) {
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swap(pa, pb);
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pa += es;
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}
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pb += es;
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}
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while (pb <= pc && (cmp_result = CMP(pc, a)) >= 0) {
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if (cmp_result == 0) {
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swap(pc, pd);
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pd -= es;
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}
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pc -= es;
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}
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if (pb > pc)
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break;
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swap(pb, pc);
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pb += es;
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pc -= es;
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}
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pn = a + n * es;
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r = min(pa - a, pb - pa);
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vecswap(a, pb - r, r);
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r = min(pd - pc, pn - pd - es);
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vecswap(pb, pn - r, r);
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/*
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* To save stack space we sort the smaller side of the partition first
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* using recursion and eliminate tail recursion for the larger side.
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*/
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r = pb - pa;
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s = pd - pc;
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if (r < s) {
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/* Recurse for 1st side, iterate for 2nd side. */
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if (s > es) {
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if (r > es) {
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introsort(a, r / es, es, maxdepth,
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swaptype, CMPARG);
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}
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a = pn - s;
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n = s / es;
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goto loop;
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}
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} else {
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/* Recurse for 2nd side, iterate for 1st side. */
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if (r > es) {
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if (s > es) {
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introsort(pn - s, s / es, es, maxdepth,
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swaptype, CMPARG);
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}
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n = r / es;
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goto loop;
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}
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}
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}
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/**
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* Sorts array w/ optional callback parameter.
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*
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* @param a is base of array
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* @param n is item count
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* @param es is item width
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* @param cmp is a callback returning <0, 0, or >0
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* @param arg is passed to callback
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* @see qsort()
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*/
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void
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qsort_r(void *a, size_t n, size_t es,
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int (*cmp)(const void *, const void *, void *), void *arg)
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{
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size_t i, maxdepth = 0;
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int swaptype;
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/* Approximate 2*ceil(lg(n + 1)) */
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for (i = n; i > 0; i >>= 1)
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maxdepth++;
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maxdepth *= 2;
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if (TYPE_ALIGNED(long, a, es))
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swaptype = es == sizeof(long) ? SWAPTYPE_LONG : SWAPTYPE_LONGV;
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else if (sizeof(int) != sizeof(long) && TYPE_ALIGNED(int, a, es))
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swaptype = es == sizeof(int) ? SWAPTYPE_INT : SWAPTYPE_INTV;
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else
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swaptype = SWAPTYPE_BYTEV;
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introsort(a, n, es, maxdepth, swaptype, CMPARG);
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}
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/**
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* Sorts array.
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*
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* This implementation uses the Quicksort routine from Bentley &
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* McIlroy's "Engineering a Sort Function", 1992, Bell Labs.
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*
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* This version differs from Bentley & McIlroy in the following ways:
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*
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* 1. The partition value is swapped into a[0] instead of being stored
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* out of line.
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*
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* 2. The swap function can swap 32-bit aligned elements on 64-bit
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* platforms instead of swapping them as byte-aligned.
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*
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* 3. It uses David Musser's introsort algorithm to fall back to
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* heapsort(3) when the recursion depth reaches 2*lg(n + 1). This
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* avoids quicksort's quadratic behavior for pathological input
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* without appreciably changing the average run time.
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*
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* 4. Tail recursion is eliminated when sorting the larger of two
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* subpartitions to save stack space.
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*
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* @param a is base of array
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* @param n is item count
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* @param es is item width
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* @param cmp is a callback returning <0, 0, or >0
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* @see mergesort()
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* @see heapsort()
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* @see qsort_r()
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* @see djbsort()
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*/
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void
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qsort(void *a, size_t n, size_t es, int (*cmp)(const void *, const void *))
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{
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qsort_r(a, n, es, (void *)cmp, 0);
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}
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