2 * SPDX-License-Identifier: BSD-3-Clause
4 * Copyright (c) 1992, 1993
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36 #include "libc_private.h"
38 #if defined(I_AM_QSORT_R)
39 typedef int cmp_t(const void *, const void *, void *);
40 #elif defined(I_AM_QSORT_R_COMPAT)
41 typedef int cmp_t(void *, const void *, const void *);
42 #elif defined(I_AM_QSORT_S)
43 typedef int cmp_t(const void *, const void *, void *);
45 typedef int cmp_t(const void *, const void *);
47 static inline char *med3(char *, char *, char *, cmp_t *, void *);
49 #define MIN(a, b) ((a) < (b) ? a : b)
52 * Qsort routine from Bentley & McIlroy's "Engineering a Sort Function".
56 swapfunc(char *a, char *b, size_t es)
67 #define vecswap(a, b, n) \
68 if ((n) > 0) swapfunc(a, b, n)
70 #if defined(I_AM_QSORT_R)
71 #define CMP(t, x, y) (cmp((x), (y), (t)))
72 #elif defined(I_AM_QSORT_R_COMPAT)
73 #define CMP(t, x, y) (cmp((t), (x), (y)))
74 #elif defined(I_AM_QSORT_S)
75 #define CMP(t, x, y) (cmp((x), (y), (t)))
77 #define CMP(t, x, y) (cmp((x), (y)))
81 med3(char *a, char *b, char *c, cmp_t *cmp, void *thunk
82 #if !defined(I_AM_QSORT_R) && !defined(I_AM_QSORT_R_COMPAT) && !defined(I_AM_QSORT_S)
87 return CMP(thunk, a, b) < 0 ?
88 (CMP(thunk, b, c) < 0 ? b : (CMP(thunk, a, c) < 0 ? c : a ))
89 :(CMP(thunk, b, c) > 0 ? b : (CMP(thunk, a, c) < 0 ? a : c ));
93 * The actual qsort() implementation is static to avoid preemptible calls when
94 * recursing. Also give them different names for improved debugging.
96 #if defined(I_AM_QSORT_R)
97 #define local_qsort local_qsort_r
98 #elif defined(I_AM_QSORT_R_COMPAT)
99 #define local_qsort local_qsort_r_compat
100 #elif defined(I_AM_QSORT_S)
101 #define local_qsort local_qsort_s
104 local_qsort(void *a, size_t n, size_t es, cmp_t *cmp, void *thunk)
106 char *pa, *pb, *pc, *pd, *pl, *pm, *pn;
111 /* if there are less than 2 elements, then sorting is not needed */
112 if (__predict_false(n < 2))
117 for (pm = (char *)a + es; pm < (char *)a + n * es; pm += es)
119 pl > (char *)a && CMP(thunk, pl - es, pl) > 0;
121 swapfunc(pl, pl - es, es);
124 pm = (char *)a + (n / 2) * es;
127 pn = (char *)a + (n - 1) * es;
129 size_t d = (n / 8) * es;
131 pl = med3(pl, pl + d, pl + 2 * d, cmp, thunk);
132 pm = med3(pm - d, pm, pm + d, cmp, thunk);
133 pn = med3(pn - 2 * d, pn - d, pn, cmp, thunk);
135 pm = med3(pl, pm, pn, cmp, thunk);
138 pa = pb = (char *)a + es;
140 pc = pd = (char *)a + (n - 1) * es;
142 while (pb <= pc && (cmp_result = CMP(thunk, pb, a)) <= 0) {
143 if (cmp_result == 0) {
145 swapfunc(pa, pb, es);
150 while (pb <= pc && (cmp_result = CMP(thunk, pc, a)) >= 0) {
151 if (cmp_result == 0) {
153 swapfunc(pc, pd, es);
160 swapfunc(pb, pc, es);
165 if (swap_cnt == 0) { /* Switch to insertion sort */
166 for (pm = (char *)a + es; pm < (char *)a + n * es; pm += es)
168 pl > (char *)a && CMP(thunk, pl - es, pl) > 0;
170 swapfunc(pl, pl - es, es);
174 pn = (char *)a + n * es;
175 d1 = MIN(pa - (char *)a, pb - pa);
176 vecswap(a, pb - d1, d1);
178 * Cast es to preserve signedness of right-hand side of MIN()
179 * expression, to avoid sign ambiguity in the implied comparison. es
180 * is safely within [0, SSIZE_MAX].
182 d1 = MIN(pd - pc, pn - pd - (ssize_t)es);
183 vecswap(pb, pn - d1, d1);
188 /* Recurse on left partition, then iterate on right partition */
190 local_qsort(a, d1 / es, es, cmp, thunk);
193 /* Iterate rather than recurse to save stack space */
194 /* qsort(pn - d2, d2 / es, es, cmp); */
200 /* Recurse on right partition, then iterate on left partition */
202 local_qsort(pn - d2, d2 / es, es, cmp, thunk);
205 /* Iterate rather than recurse to save stack space */
206 /* qsort(a, d1 / es, es, cmp); */
213 #if defined(I_AM_QSORT_R)
215 (qsort_r)(void *a, size_t n, size_t es, cmp_t *cmp, void *thunk)
217 local_qsort_r(a, n, es, cmp, thunk);
219 #elif defined(I_AM_QSORT_R_COMPAT)
221 __qsort_r_compat(void *a, size_t n, size_t es, void *thunk, cmp_t *cmp)
223 local_qsort_r_compat(a, n, es, cmp, thunk);
225 #elif defined(I_AM_QSORT_S)
227 qsort_s(void *a, rsize_t n, rsize_t es, cmp_t *cmp, void *thunk)
230 __throw_constraint_handler_s("qsort_s : n > RSIZE_MAX", EINVAL);
232 } else if (es > RSIZE_MAX) {
233 __throw_constraint_handler_s("qsort_s : es > RSIZE_MAX",
238 __throw_constraint_handler_s("qsort_s : a == NULL",
241 } else if (cmp == NULL) {
242 __throw_constraint_handler_s("qsort_s : cmp == NULL",
245 } else if (es <= 0) {
246 __throw_constraint_handler_s("qsort_s : es <= 0",
252 local_qsort_s(a, n, es, cmp, thunk);
257 qsort(void *a, size_t n, size_t es, cmp_t *cmp)
259 local_qsort(a, n, es, cmp, NULL);