diff options
Diffstat (limited to 'usr.bin/sort/radix_sort.c')
| -rw-r--r-- | usr.bin/sort/radix_sort.c | 217 |
1 files changed, 217 insertions, 0 deletions
diff --git a/usr.bin/sort/radix_sort.c b/usr.bin/sort/radix_sort.c new file mode 100644 index 0000000..4ec5ff8 --- /dev/null +++ b/usr.bin/sort/radix_sort.c @@ -0,0 +1,217 @@ +/* $NetBSD: radix_sort.c,v 1.4 2009/09/19 16:18:00 dsl Exp $ */ + +/*- + * Copyright (c) 1990, 1993 + * The Regents of the University of California. All rights reserved. + * + * This code is derived from software contributed to Berkeley by + * Peter McIlroy and by Dan Bernstein at New York University, + * + * 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. + */ + +#include <sys/cdefs.h> +#if defined(LIBC_SCCS) && !defined(lint) +#if 0 +static char sccsid[] = "@(#)radixsort.c 8.2 (Berkeley) 4/28/95"; +#else +__RCSID("$NetBSD: radix_sort.c,v 1.4 2009/09/19 16:18:00 dsl Exp $"); +#endif +#endif /* LIBC_SCCS and not lint */ + +/* + * 'stable' radix sort initially from libc/stdlib/radixsort.c + */ + +#include <sys/types.h> + +#include <assert.h> +#include <errno.h> +#include <util.h> +#include "sort.h" + +typedef struct { + RECHEADER **sa; /* Base of saved area */ + int sn; /* Number of entries */ + int si; /* index into data for compare */ +} stack; + +static void simplesort(RECHEADER **, int, int); + +#define THRESHOLD 20 /* Divert to simplesort(). */ + +#define empty(s) (s >= sp) +#define pop(a, n, i) a = (--sp)->sa, n = sp->sn, i = sp->si +#define push(a, n, i) sp->sa = a, sp->sn = n, (sp++)->si = i +#define swap(a, b, t) t = a, a = b, b = t + +void +radix_sort(RECHEADER **a, RECHEADER **ta, int n) +{ + u_int count[256], nc, bmin; + u_int c; + RECHEADER **ak, **tai, **lim; + RECHEADER *hdr; + int stack_size = 512; + stack *s, *sp, *sp0, *sp1, temp; + RECHEADER **top[256]; + u_int *cp, bigc; + int data_index = 0; + + if (n < THRESHOLD && !DEBUG('r')) { + simplesort(a, n, 0); + return; + } + + s = emalloc(stack_size * sizeof *s); + memset(&count, 0, sizeof count); + /* Technically 'top' doesn't need zeroing */ + memset(&top, 0, sizeof top); + + sp = s; + push(a, n, data_index); + while (!empty(s)) { + pop(a, n, data_index); + if (n < THRESHOLD && !DEBUG('r')) { + simplesort(a, n, data_index); + continue; + } + + /* Count number of times each 'next byte' occurs */ + nc = 0; + bmin = 255; + lim = a + n; + for (ak = a, tai = ta; ak < lim; ak++) { + hdr = *ak; + if (data_index >= hdr->keylen) { + /* Short key, copy to start of output */ + if (UNIQUE && a != sp->sa) + /* Stop duplicate being written out */ + hdr->keylen = -1; + *a++ = hdr; + n--; + continue; + } + /* Save in temp buffer for distribute */ + *tai++ = hdr; + c = hdr->data[data_index]; + if (++count[c] == 1) { + if (c < bmin) + bmin = c; + nc++; + } + } + /* + * We need save the bounds for each 'next byte' that + * occurs more so we can sort each block. + */ + if (sp + nc > s + stack_size) { + stack_size *= 2; + sp1 = erealloc(s, stack_size * sizeof *s); + sp = sp1 + (sp - s); + s = sp1; + } + + /* Minor optimisation to do the largest set last */ + sp0 = sp1 = sp; + bigc = 2; + /* Convert 'counts' positions, saving bounds for later sorts */ + ak = a; + for (cp = count + bmin; nc > 0; cp++) { + while (*cp == 0) + cp++; + if ((c = *cp) > 1) { + if (c > bigc) { + bigc = c; + sp1 = sp; + } + push(ak, c, data_index+1); + } + ak += c; + top[cp-count] = ak; + *cp = 0; /* Reset count[]. */ + nc--; + } + swap(*sp0, *sp1, temp); + + for (ak = ta+n; --ak >= ta;) /* Deal to piles. */ + *--top[(*ak)->data[data_index]] = *ak; + } + + free(s); +} + +/* insertion sort, short records are sorted before long ones */ +static void +simplesort(RECHEADER **a, int n, int data_index) +{ + RECHEADER **ak, **ai; + RECHEADER *akh; + RECHEADER **lim = a + n; + const u_char *s, *t; + int s_len, t_len; + int i; + int r; + + if (n <= 1) + return; + + for (ak = a+1; ak < lim; ak++) { + akh = *ak; + s = akh->data; + s_len = akh->keylen; + for (ai = ak; ;) { + ai--; + t_len = (*ai)->keylen; + if (t_len != -1) { + t = (*ai)->data; + for (i = data_index; ; i++) { + if (i >= s_len || i >= t_len) { + r = s_len - t_len; + break; + } + r = s[i] - t[i]; + if (r != 0) + break; + } + if (r >= 0) { + if (r == 0 && UNIQUE) { + /* Put record below existing */ + ai[1] = ai[0]; + /* Mark as duplicate - ignore */ + akh->keylen = -1; + } else { + ai++; + } + break; + } + } + ai[1] = ai[0]; + if (ai == a) + break; + } + ai[0] = akh; + } +} |