cosmopolitan/libc/str/intsort.c
Jōshin 394d998315
Fix vi modelines (#989)
At least in neovim, `│vi:` is not recognized as a modeline because it
has no preceding whitespace. After fixing this, opening a file yields
an error because `net` is not an option. (`noet`, however, is.)
2023-12-05 14:37:54 -08:00

63 lines
2.6 KiB
C

/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
│ vi: set noet ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi │
╞══════════════════════════════════════════════════════════════════════════════╡
│ Copyright 2021 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/strace.internal.h"
#include "libc/runtime/runtime.h"
static inline void InsertionSort(int *A, long n) {
long i, j, t;
for (i = 1; i < n; i++) {
t = A[i];
j = i - 1;
while (j >= 0 && A[j] > t) {
A[j + 1] = A[j];
j = j - 1;
}
A[j + 1] = t;
}
}
static void IntSort(int *A, long n) {
int t, p;
long i, j;
if (n <= 32) {
InsertionSort(A, n);
} else {
for (p = A[n >> 1], i = 0, j = n - 1;; i++, j--) {
while (A[i] < p) i++;
while (A[j] > p) j--;
if (i >= j) break;
t = A[i];
A[i] = A[j];
A[j] = t;
}
IntSort(A, i);
IntSort(A + i, n - i);
}
}
/**
* Tiny and reasonably fast sorting for ints.
* @see djbsort
*/
void _intsort(int *A, size_t n) {
IntSort(A, n);
if (n > 1000) {
STRACE("_intsort(%p, %'zu)", A, n);
}
}