Edit
kc3-lang/libbsd/src/radixsort.c
Guillem Jover
- src/radixsort.c
-
/* $NetBSD: radixsort.c,v 1.18 2009/08/21 20:49:50 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> /* * Radixsort routines. * * Program r_sort_a() is unstable but uses O(logN) extra memory for a stack. * Use radixsort(a, n, trace, endchar) for this case. * * For stable sorting (using N extra pointers) use sradixsort(), which calls * r_sort_b(). * * For a description of this code, see D. McIlroy, P. McIlroy, K. Bostic, * "Engineering Radix Sort". */ #include <sys/types.h> #include <stdlib.h> #include <stddef.h> #include <errno.h> typedef struct { const unsigned char **sa; int sn, si; } stack; static inline void simplesort(const unsigned char **, int, int, const unsigned char *, unsigned int); static void r_sort_a(const unsigned char **, int, int, const unsigned char *, unsigned int); static void r_sort_b(const unsigned char **, const unsigned char **, int, int, const unsigned char *, unsigned int); #define THRESHOLD 20 /* Divert to simplesort(). */ #define SIZE 512 /* Default stack size. */ #define SETUP { \ if (tab == NULL) { \ tr = tr0; \ for (c = 0; c < endch; c++) \ tr0[c] = c + 1; \ tr0[c] = 0; \ for (c++; c < 256; c++) \ tr0[c] = c; \ endch = 0; \ } else { \ endch = tab[endch]; \ tr = tab; \ if (endch != 0 && endch != 255) { \ errno = EINVAL; \ return (-1); \ } \ } \ } int radixsort(const unsigned char **a, int n, const unsigned char *tab, unsigned int endch) { const unsigned char *tr; unsigned int c; unsigned char tr0[256]; SETUP; r_sort_a(a, n, 0, tr, endch); return (0); } int sradixsort(const unsigned char **a, int n, const unsigned char *tab, unsigned int endch) { const unsigned char *tr, **ta; unsigned int c; unsigned char tr0[256]; if (a == NULL) { errno = EFAULT; return (-1); } SETUP; if (n < THRESHOLD) simplesort(a, n, 0, tr, endch); else { ta = reallocarray(NULL, n, sizeof(*a)); if (ta == NULL) return (-1); r_sort_b(a, ta, n, 0, tr, endch); free(ta); } return (0); } #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 /* Unstable, in-place sort. */ static void r_sort_a(const unsigned char **a, int n, int i, const unsigned char *tr, unsigned int endch) { static unsigned int count[256], nc, bmin; unsigned int c; const unsigned char **ak, *r; stack s[SIZE], *sp, *sp0, *sp1, temp; unsigned int *cp, bigc; const unsigned char **an, *t, **aj, **top[256]; /* Set up stack. */ sp = s; push(a, n, i); while (!empty(s)) { pop(a, n, i); if (n < THRESHOLD) { simplesort(a, n, i, tr, endch); continue; } an = a + n; /* Make character histogram. */ if (nc == 0) { bmin = 255; /* First occupied bin, excluding eos. */ for (ak = a; ak < an;) { c = tr[(*ak++)[i]]; if (++count[c] == 1 && c != endch) { if (c < bmin) bmin = c; nc++; } } if (sp + nc > s + SIZE) { /* Get more stack. */ r_sort_a(a, n, i, tr, endch); continue; } } /* * Special case: if all strings have the same * character at position i, move on to the next * character. */ if (nc == 1 && count[bmin] == (unsigned int)n) { push(a, n, i+1); nc = count[bmin] = 0; continue; } /* * Set top[]; push incompletely sorted bins onto stack. * top[] = pointers to last out-of-place element in bins. * count[] = counts of elements in bins. * Before permuting: top[c-1] + count[c] = top[c]; * during deal: top[c] counts down to top[c-1]. */ sp0 = sp1 = sp; /* Stack position of biggest bin. */ bigc = 2; /* Size of biggest bin. */ if (endch == 0) /* Special case: set top[eos]. */ top[0] = ak = a + count[0]; else { ak = a; top[255] = an; } for (cp = count + bmin; nc > 0; cp++) { while (*cp == 0) /* Find next non-empty pile. */ cp++; if (*cp > 1) { if (*cp > bigc) { bigc = *cp; sp1 = sp; } push(ak, *cp, i+1); } top[cp-count] = ak += *cp; nc--; } swap(*sp0, *sp1, temp); /* Play it safe -- biggest bin last. */ /* * Permute misplacements home. Already home: everything * before aj, and in bin[c], items from top[c] on. * Inner loop: * r = next element to put in place; * ak = top[r[i]] = location to put the next element. * aj = bottom of 1st disordered bin. * Outer loop: * Once the 1st disordered bin is done, ie. aj >= ak, * aj<-aj + count[c] connects the bins in a linked list; * reset count[c]. */ for (aj = a; aj < an; *aj = r, aj += count[c], count[c] = 0) for (r = *aj; aj < (ak = --top[c = tr[r[i]]]);) swap(*ak, r, t); } } /* Stable sort, requiring additional memory. */ static void r_sort_b(const unsigned char **a, const unsigned char **ta, int n, int i, const unsigned char *tr, unsigned int endch) { static unsigned int count[256], nc, bmin; unsigned int c; const unsigned char **ak, **ai; stack s[512], *sp, *sp0, *sp1, temp; const unsigned char **top[256]; unsigned int *cp, bigc; sp = s; push(a, n, i); while (!empty(s)) { pop(a, n, i); if (n < THRESHOLD) { simplesort(a, n, i, tr, endch); continue; } if (nc == 0) { bmin = 255; for (ak = a + n; --ak >= a;) { c = tr[(*ak)[i]]; if (++count[c] == 1 && c != endch) { if (c < bmin) bmin = c; nc++; } } if (sp + nc > s + SIZE) { r_sort_b(a, ta, n, i, tr, endch); continue; } } sp0 = sp1 = sp; bigc = 2; if (endch == 0) { top[0] = ak = a + count[0]; count[0] = 0; } else { ak = a; top[255] = a + n; count[255] = 0; } 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, i+1); } top[cp-count] = ak += c; *cp = 0; /* Reset count[]. */ nc--; } swap(*sp0, *sp1, temp); for (ak = ta + n, ai = a+n; ak > ta;) /* Copy to temp. */ *--ak = *--ai; for (ak = ta+n; --ak >= ta;) /* Deal to piles. */ *--top[tr[(*ak)[i]]] = *ak; } } /* insertion sort */ static inline void simplesort(const unsigned char **a, int n, int b, const unsigned char *tr, unsigned int endch) { unsigned char ch; const unsigned char **ak, **ai, *s, *t; for (ak = a+1; --n >= 1; ak++) for (ai = ak; ai > a; ai--) { for (s = ai[0] + b, t = ai[-1] + b; (ch = tr[*s]) != endch; s++, t++) if (ch != tr[*t]) break; if (ch >= tr[*t]) break; swap(ai[0], ai[-1], s); } }