text: /*-
   * Copyright (c) 1992, 1993
   *	The Regents of the University of California.  All rights reserved.
   *
   * This code is derived from software contributed to Berkeley by
   * Peter McIlroy.
   *
   * 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. All advertising materials mentioning features or use of this software
   *    must display the following acknowledgement:
   *	This product includes software developed by the University of
   *	California, Berkeley and its contributors.
   * 4. 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[] = "@(#)merge.c	8.2 (Berkeley) 2/14/94";
  #endif /* LIBC_SCCS and not lint */
  
  /*
   * Hybrid exponential search/linear search merge sort with hybrid
   * natural/pairwise first pass.  Requires about .3% more comparisons
   * for random data than LSMS with pairwise first pass alone.
   * It works for objects as small as two bytes.
   */
  
  #define NATURAL
  #define THRESHOLD 16	/* Best choice for natural merge cut-off. */
  
  /* #define NATURAL to get hybrid natural merge.
   * (The default is pairwise merging.)
   */
  
  #include <sys/types.h>
  
  #include <errno.h>
  #include <stdlib.h>
  #include <string.h>
  
  #include "php.h"
  
  #ifdef PHP_WIN32
  #include <winsock2.h> /* Includes definition for u_char */
  #endif
  
  static void setup(u_char *list1, u_char *list2, size_t n, size_t size, int (*cmp)(const void *, const void *));
  static void insertionsort(u_char *a, size_t n, size_t size, int (*cmp)(const void *, const void *));
  
  #define ISIZE sizeof(int)
  #define PSIZE sizeof(u_char *)
  #define ICOPY_LIST(src, dst, last)				\
  	do							\
  	*(int*)dst = *(int*)src, src += ISIZE, dst += ISIZE;	\
  	while(src < last)
  #define ICOPY_ELT(src, dst, i)					\
  	do							\
  	*(int*) dst = *(int*) src, src += ISIZE, dst += ISIZE;	\
  	while (i -= ISIZE)
  
  #define CCOPY_LIST(src, dst, last)		\
  	do					\
  		*dst++ = *src++;		\
  	while (src < last)
  #define CCOPY_ELT(src, dst, i)			\
  	do					\
  		*dst++ = *src++;		\
  	while (i -= 1)
  
  /*
   * Find the next possible pointer head.  (Trickery for forcing an array
   * to do double duty as a linked list when objects do not align with word
   * boundaries.
   */
  /* Assumption: PSIZE is a power of 2. */
  #define EVAL(p) (u_char **)						\
         	((u_char *)0 +							\
  	    (((u_char *)p + PSIZE - 1 - (u_char *) 0) & ~(PSIZE - 1)))
  
  /* {{{ php_mergesort
   * Arguments are as for qsort.
   */
  PHPAPI int php_mergesort(void *base, size_t nmemb, size_t size, int (*cmp)(const void *, const void *))
  {
  	register size_t i;
  	register int sense;
  	int big, iflag;
  	register u_char *f1, *f2, *t, *b, *tp2, *q, *l1, *l2;
  	u_char *list2, *list1, *p2, *p, *last, **p1;
  
  	if (size < PSIZE / 2) {		/* Pointers must fit into 2 * size. */
  		errno = EINVAL;
  		return (-1);
  	}
  
  	if (nmemb == 0)
  		return (0);
  
  	/*
  	 * XXX
  	 * Stupid subtraction for the Cray.
  	 */
  	iflag = 0;
  	if (!(size % ISIZE) && !(((char *)base - (char *)0) % ISIZE))
  		iflag = 1;
  
  	if ((list2 = malloc(nmemb * size + PSIZE)) == NULL)
  		return (-1);
  
  	list1 = base;
  	setup(list1, list2, nmemb, size, cmp);
  	last = list2 + nmemb * size;
  	i = big = 0;
  	while (*EVAL(list2) != last) {
  	    l2 = list1;
  	    p1 = EVAL(list1);
  	    for (tp2 = p2 = list2; p2 != last; p1 = EVAL(l2)) {
  	    	p2 = *EVAL(p2);
  	    	f1 = l2;
  	    	f2 = l1 = list1 + (p2 - list2);
  	    	if (p2 != last)
  	    		p2 = *EVAL(p2);
  	    	l2 = list1 + (p2 - list2);
  	    	while (f1 < l1 && f2 < l2) {
  	    		if ((*cmp)(f1, f2) <= 0) {
  	    			q = f2;
  	    			b = f1, t = l1;
  	    			sense = -1;
  	    		} else {
  	    			q = f1;
  	    			b = f2, t = l2;
  	    			sense = 0;
  	    		}
  	    		if (!big) {	/* here i = 0 */
  				while ((b += size) < t && cmp(q, b) >sense)
  	    				if (++i == 6) {
  	    					big = 1;
  	    					goto EXPONENTIAL;
  	    				}
  	    		} else {
  EXPONENTIAL:	    		for (i = size; ; i <<= 1)
  	    				if ((p = (b + i)) >= t) {
  	    					if ((p = t - size) > b &&
  						    (*cmp)(q, p) <= sense)
  	    						t = p;
  	    					else
  	    						b = p;
  	    					break;
  	    				} else if ((*cmp)(q, p) <= sense) {
  	    					t = p;
  	    					if (i == size)
  	    						big = 0;
  	    					goto FASTCASE;
  	    				} else
  	    					b = p;
  				while (t > b+size) {
  	    				i = (((t - b) / size) >> 1) * size;
  	    				if ((*cmp)(q, p = b + i) <= sense)
  	    					t = p;
  	    				else
  	    					b = p;
  	    			}
  	    			goto COPY;
  FASTCASE:	    		while (i > size)
  	    				if ((*cmp)(q,
  	    					p = b + (i >>= 1)) <= sense)
  	    					t = p;
  	    				else
  	    					b = p;
  COPY:	    			b = t;
  	    		}
  	    		i = size;
  	    		if (q == f1) {
  	    			if (iflag) {
  	    				ICOPY_LIST(f2, tp2, b);
  	    				ICOPY_ELT(f1, tp2, i);
  	    			} else {
  	    				CCOPY_LIST(f2, tp2, b);
  	    				CCOPY_ELT(f1, tp2, i);
  	    			}
  	    		} else {
  	    			if (iflag) {
  	    				ICOPY_LIST(f1, tp2, b);
  	    				ICOPY_ELT(f2, tp2, i);
  	    			} else {
  	    				CCOPY_LIST(f1, tp2, b);
  	    				CCOPY_ELT(f2, tp2, i);
  	    			}
  	    		}
  	    	}
  	    	if (f2 < l2) {
  	    		if (iflag)
  	    			ICOPY_LIST(f2, tp2, l2);
  	    		else
  	    			CCOPY_LIST(f2, tp2, l2);
  	    	} else if (f1 < l1) {
  	    		if (iflag)
  	    			ICOPY_LIST(f1, tp2, l1);
  	    		else
  	    			CCOPY_LIST(f1, tp2, l1);
  	    	}
  	    	*p1 = l2;
  	    }
  	    tp2 = list1;	/* swap list1, list2 */
  	    list1 = list2;
  	    list2 = tp2;
  	    last = list2 + nmemb*size;
  	}
  	if (base == list2) {
  		memmove(list2, list1, nmemb*size);
  		list2 = list1;
  	}
  	free(list2);
  	return (0);
  }
  /* }}} */
  
  #define	swap(a, b) {					\
  		s = b;					\
  		i = size;				\
  		do {					\
  			tmp = *a; *a++ = *s; *s++ = tmp; \
  		} while (--i);				\
  		a -= size;				\
  	}
  #define reverse(bot, top) {				\
  	s = top;					\
  	do {						\
  		i = size;				\
  		do {					\
  			tmp = *bot; *bot++ = *s; *s++ = tmp; \
  		} while (--i);				\
  		s -= size2;				\
  	} while(bot < s);				\
  }
  
  /* {{{ setup
   * Optional hybrid natural/pairwise first pass.  Eats up list1 in runs of
   * increasing order, list2 in a corresponding linked list.  Checks for runs
   * when THRESHOLD/2 pairs compare with same sense.  (Only used when NATURAL
   * is defined.  Otherwise simple pairwise merging is used.)
   */
  static void setup(u_char *list1, u_char *list2, size_t n, size_t size, int (*cmp)(const void *, const void *))
  {
  	size_t i, length, size2, sense;
  	u_char *f1, *f2, *s, *l2, *last, *p2, tmp;
  
  	size2 = size*2;
  	if (n <= 5) {
  		insertionsort(list1, n, size, cmp);
  		*EVAL(list2) = (u_char*) list2 + n*size;
  		return;
  	}
  	/*
  	 * Avoid running pointers out of bounds; limit n to evens
  	 * for simplicity.
  	 */
  	i = 4 + (n & 1);
  	insertionsort(list1 + (n - i) * size, i, size, cmp);
  	last = list1 + size * (n - i);
  	*EVAL(list2 + (last - list1)) = list2 + n * size;
  
  #ifdef NATURAL
  	p2 = list2;
  	f1 = list1;
  	sense = (cmp(f1, f1 + size) > 0);
  	for (; f1 < last; sense = !sense) {
  		length = 2;
  					/* Find pairs with same sense. */
  		for (f2 = f1 + size2; f2 < last; f2 += size2) {
  			if ((cmp(f2, f2+ size) > 0) != sense)
  				break;
  			length += 2;
  		}
  		if (length < THRESHOLD) {		/* Pairwise merge */
  			do {
  				p2 = *EVAL(p2) = f1 + size2 - list1 + list2;
  				if (sense > 0)
  					swap (f1, f1 + size);
  			} while ((f1 += size2) < f2);
  		} else {				/* Natural merge */
  			l2 = f2;
  			for (f2 = f1 + size2; f2 < l2; f2 += size2) {
  				if ((cmp(f2-size, f2) > 0) != sense) {
  					p2 = *EVAL(p2) = f2 - list1 + list2;
  					if (sense > 0)
  						reverse(f1, f2-size);
  					f1 = f2;
  				}
  			}
  			if (sense > 0)
  				reverse (f1, f2-size);
  			f1 = f2;
  			if (f2 < last || cmp(f2 - size, f2) > 0)
  				p2 = *EVAL(p2) = f2 - list1 + list2;
  			else
  				p2 = *EVAL(p2) = list2 + n*size;
  		}
  	}
  #else		/* pairwise merge only. */
  	for (f1 = list1, p2 = list2; f1 < last; f1 += size2) {
  		p2 = *EVAL(p2) = p2 + size2;
  		if (cmp (f1, f1 + size) > 0)
  			swap(f1, f1 + size);
  	}
  #endif /* NATURAL */
  }
  /* }}} */
  
  /* {{{ insertionsort
   * This is to avoid out-of-bounds addresses in sorting the
   * last 4 elements.
   */
  static void insertionsort(u_char *a, size_t n, size_t size, int (*cmp)(const void *, const void *))
  {
  	u_char *ai, *s, *t, *u, tmp;
  	size_t i;
  
  	for (ai = a+size; --n >= 1; ai += size)
  		for (t = ai; t > a; t -= size) {
  			u = t - size;
  			if (cmp(u, t) <= 0)
  				break;
  			swap(u, t);
  		}
  }
  /* }}} */
  
  /*
   * Local variables:
   * tab-width: 4
   * c-basic-offset: 4
   * End:
   * vim600: fdm=marker
   * vim: noet sw=4 ts=4
   */
  