diff --git a/lib/libc/stdlib/qsort.c b/lib/libc/stdlib/qsort.c index 425edd562420..0d65cd119ea6 100644 --- a/lib/libc/stdlib/qsort.c +++ b/lib/libc/stdlib/qsort.c @@ -1,266 +1,267 @@ /*- * SPDX-License-Identifier: BSD-3-Clause * * Copyright (c) 1992, 1993 * The Regents of the University of California. All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * 3. Neither the name of the University nor the names of its contributors * may be used to endorse or promote products derived from this software * without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. */ #if defined(LIBC_SCCS) && !defined(lint) static char sccsid[] = "@(#)qsort.c 8.1 (Berkeley) 6/4/93"; #endif /* LIBC_SCCS and not lint */ #include __FBSDID("$FreeBSD$"); #include #include #include #include #include "libc_private.h" #if defined(I_AM_QSORT_R) typedef int cmp_t(const void *, const void *, void *); #elif defined(I_AM_QSORT_R_COMPAT) typedef int cmp_t(void *, const void *, const void *); #elif defined(I_AM_QSORT_S) typedef int cmp_t(const void *, const void *, void *); #else typedef int cmp_t(const void *, const void *); #endif static inline char *med3(char *, char *, char *, cmp_t *, void *); #define MIN(a, b) ((a) < (b) ? a : b) /* * Qsort routine from Bentley & McIlroy's "Engineering a Sort Function". */ static inline void swapfunc(char *a, char *b, size_t es) { char t; do { t = *a; *a++ = *b; *b++ = t; } while (--es > 0); } #define vecswap(a, b, n) \ if ((n) > 0) swapfunc(a, b, n) #if defined(I_AM_QSORT_R) #define CMP(t, x, y) (cmp((x), (y), (t))) #elif defined(I_AM_QSORT_R_COMPAT) #define CMP(t, x, y) (cmp((t), (x), (y))) #elif defined(I_AM_QSORT_S) #define CMP(t, x, y) (cmp((x), (y), (t))) #else #define CMP(t, x, y) (cmp((x), (y))) #endif static inline char * med3(char *a, char *b, char *c, cmp_t *cmp, void *thunk #if !defined(I_AM_QSORT_R) && !defined(I_AM_QSORT_R_COMPAT) && !defined(I_AM_QSORT_S) __unused #endif ) { return CMP(thunk, a, b) < 0 ? (CMP(thunk, b, c) < 0 ? b : (CMP(thunk, a, c) < 0 ? c : a )) :(CMP(thunk, b, c) > 0 ? b : (CMP(thunk, a, c) < 0 ? a : c )); } /* * The actual qsort() implementation is static to avoid preemptible calls when * recursing. Also give them different names for improved debugging. */ #if defined(I_AM_QSORT_R) #define local_qsort local_qsort_r #elif defined(I_AM_QSORT_R_COMPAT) #define local_qsort local_qsort_r_compat #elif defined(I_AM_QSORT_S) #define local_qsort local_qsort_s #endif static void local_qsort(void *a, size_t n, size_t es, cmp_t *cmp, void *thunk) { char *pa, *pb, *pc, *pd, *pl, *pm, *pn; size_t d1, d2; int cmp_result; int swap_cnt; - if (__predict_false(n == 0)) + /* if there are less than 2 elements, then sorting is not needed */ + if (__predict_false(n < 2)) return; loop: swap_cnt = 0; if (n < 7) { for (pm = (char *)a + es; pm < (char *)a + n * es; pm += es) for (pl = pm; pl > (char *)a && CMP(thunk, pl - es, pl) > 0; pl -= es) swapfunc(pl, pl - es, es); return; } pm = (char *)a + (n / 2) * es; if (n > 7) { pl = a; pn = (char *)a + (n - 1) * es; if (n > 40) { size_t d = (n / 8) * es; pl = med3(pl, pl + d, pl + 2 * d, cmp, thunk); pm = med3(pm - d, pm, pm + d, cmp, thunk); pn = med3(pn - 2 * d, pn - d, pn, cmp, thunk); } pm = med3(pl, pm, pn, cmp, thunk); } swapfunc(a, pm, es); pa = pb = (char *)a + es; pc = pd = (char *)a + (n - 1) * es; for (;;) { while (pb <= pc && (cmp_result = CMP(thunk, pb, a)) <= 0) { if (cmp_result == 0) { swap_cnt = 1; swapfunc(pa, pb, es); pa += es; } pb += es; } while (pb <= pc && (cmp_result = CMP(thunk, pc, a)) >= 0) { if (cmp_result == 0) { swap_cnt = 1; swapfunc(pc, pd, es); pd -= es; } pc -= es; } if (pb > pc) break; swapfunc(pb, pc, es); swap_cnt = 1; pb += es; pc -= es; } if (swap_cnt == 0) { /* Switch to insertion sort */ for (pm = (char *)a + es; pm < (char *)a + n * es; pm += es) for (pl = pm; pl > (char *)a && CMP(thunk, pl - es, pl) > 0; pl -= es) swapfunc(pl, pl - es, es); return; } pn = (char *)a + n * es; d1 = MIN(pa - (char *)a, pb - pa); vecswap(a, pb - d1, d1); /* * Cast es to preserve signedness of right-hand side of MIN() * expression, to avoid sign ambiguity in the implied comparison. es * is safely within [0, SSIZE_MAX]. */ d1 = MIN(pd - pc, pn - pd - (ssize_t)es); vecswap(pb, pn - d1, d1); d1 = pb - pa; d2 = pd - pc; if (d1 <= d2) { /* Recurse on left partition, then iterate on right partition */ if (d1 > es) { local_qsort(a, d1 / es, es, cmp, thunk); } if (d2 > es) { /* Iterate rather than recurse to save stack space */ /* qsort(pn - d2, d2 / es, es, cmp); */ a = pn - d2; n = d2 / es; goto loop; } } else { /* Recurse on right partition, then iterate on left partition */ if (d2 > es) { local_qsort(pn - d2, d2 / es, es, cmp, thunk); } if (d1 > es) { /* Iterate rather than recurse to save stack space */ /* qsort(a, d1 / es, es, cmp); */ n = d1 / es; goto loop; } } } #if defined(I_AM_QSORT_R) void (qsort_r)(void *a, size_t n, size_t es, cmp_t *cmp, void *thunk) { local_qsort_r(a, n, es, cmp, thunk); } #elif defined(I_AM_QSORT_R_COMPAT) void __qsort_r_compat(void *a, size_t n, size_t es, void *thunk, cmp_t *cmp) { local_qsort_r_compat(a, n, es, cmp, thunk); } #elif defined(I_AM_QSORT_S) errno_t qsort_s(void *a, rsize_t n, rsize_t es, cmp_t *cmp, void *thunk) { if (n > RSIZE_MAX) { __throw_constraint_handler_s("qsort_s : n > RSIZE_MAX", EINVAL); return (EINVAL); } else if (es > RSIZE_MAX) { __throw_constraint_handler_s("qsort_s : es > RSIZE_MAX", EINVAL); return (EINVAL); } else if (n != 0) { if (a == NULL) { __throw_constraint_handler_s("qsort_s : a == NULL", EINVAL); return (EINVAL); } else if (cmp == NULL) { __throw_constraint_handler_s("qsort_s : cmp == NULL", EINVAL); return (EINVAL); } else if (es <= 0) { __throw_constraint_handler_s("qsort_s : es <= 0", EINVAL); return (EINVAL); } } local_qsort_s(a, n, es, cmp, thunk); return (0); } #else void qsort(void *a, size_t n, size_t es, cmp_t *cmp) { local_qsort(a, n, es, cmp, NULL); } #endif