1 /* PSPP - computes sample statistics.
2 Copyright (C) 1997-9, 2000 Free Software Foundation, Inc.
4 This program is free software; you can redistribute it and/or
5 modify it under the terms of the GNU General Public License as
6 published by the Free Software Foundation; either version 2 of the
7 License, or (at your option) any later version.
9 This program is distributed in the hope that it will be useful, but
10 WITHOUT ANY WARRANTY; without even the implied warranty of
11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
12 General Public License for more details.
14 You should have received a copy of the GNU General Public License
15 along with this program; if not, write to the Free Software
16 Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
19 /* Copyright (C) 2001 Free Software Foundation, Inc.
21 This file is part of the GNU ISO C++ Library. This library is free
22 software; you can redistribute it and/or modify it under the
23 terms of the GNU General Public License as published by the
24 Free Software Foundation; either version 2, or (at your option)
27 This library is distributed in the hope that it will be useful,
28 but WITHOUT ANY WARRANTY; without even the implied warranty of
29 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
30 GNU General Public License for more details.
32 You should have received a copy of the GNU General Public License along
33 with this library; see the file COPYING. If not, write to the Free
34 Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
37 As a special exception, you may use this file as part of a free software
38 library without restriction. Specifically, if other files instantiate
39 templates or use macros or inline functions from this file, or you compile
40 this file and link it with other files to produce an executable, this
41 file does not by itself cause the resulting executable to be covered by
42 the GNU General Public License. This exception does not however
43 invalidate any other reasons why the executable file might be covered by
44 the GNU General Public License. */
49 * Hewlett-Packard Company
51 * Permission to use, copy, modify, distribute and sell this software
52 * and its documentation for any purpose is hereby granted without fee,
53 * provided that the above copyright notice appear in all copies and
54 * that both that copyright notice and this permission notice appear
55 * in supporting documentation. Hewlett-Packard Company makes no
56 * representations about the suitability of this software for any
57 * purpose. It is provided "as is" without express or implied warranty.
61 * Silicon Graphics Computer Systems, Inc.
63 * Permission to use, copy, modify, distribute and sell this software
64 * and its documentation for any purpose is hereby granted without fee,
65 * provided that the above copyright notice appear in all copies and
66 * that both that copyright notice and this permission notice appear
67 * in supporting documentation. Silicon Graphics makes no
68 * representations about the suitability of this software for any
69 * purpose. It is provided "as is" without express or implied warranty.
72 /* Copyright (C) 1991, 1992, 1996, 1997, 1999 Free Software Foundation, Inc.
73 This file is part of the GNU C Library.
74 Written by Douglas C. Schmidt (schmidt@ics.uci.edu).
76 The GNU C Library is free software; you can redistribute it and/or
77 modify it under the terms of the GNU Lesser General Public
78 License as published by the Free Software Foundation; either
79 version 2.1 of the License, or (at your option) any later version.
81 The GNU C Library is distributed in the hope that it will be useful,
82 but WITHOUT ANY WARRANTY; without even the implied warranty of
83 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
84 Lesser General Public License for more details.
86 You should have received a copy of the GNU Lesser General Public
87 License along with the GNU C Library; if not, write to the Free
88 Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
97 #include <libpspp/assertion.h>
103 /* Finds an element in ARRAY, which contains COUNT elements of
104 SIZE bytes each, using COMPARE for comparisons. Returns the
105 first element in ARRAY that matches TARGET, or a null pointer
106 on failure. AUX is passed to each comparison as auxiliary
109 find (const void *array, size_t count, size_t size,
111 algo_compare_func *compare, const void *aux)
113 const char *element = array;
117 if (compare (target, element, aux) == 0)
118 return (void *) element;
126 /* Counts and return the number of elements in ARRAY, which
127 contains COUNT elements of SIZE bytes each, which are equal to
128 ELEMENT as compared with COMPARE. AUX is passed as auxiliary
131 count_equal (const void *array, size_t count, size_t size,
133 algo_compare_func *compare, const void *aux)
135 const char *first = array;
136 size_t equal_cnt = 0;
140 if (compare (element, first, aux) == 0)
149 /* Counts and return the number of elements in ARRAY, which
150 contains COUNT elements of SIZE bytes each, for which
151 PREDICATE returns true. AUX is passed as auxiliary data to
154 count_if (const void *array, size_t count, size_t size,
155 algo_predicate_func *predicate, const void *aux)
157 const char *first = array;
162 if (predicate (first, aux) != 0)
171 /* Byte-wise swap two items of size SIZE. */
172 #define SWAP(a, b, size) \
175 register size_t __size = (size); \
176 register char *__a = (a), *__b = (b); \
182 } while (--__size > 0); \
185 /* Makes the elements in ARRAY unique, by moving up duplicates,
186 and returns the new number of elements in the array. Sorted
187 arrays only. Arguments same as for sort() above. */
189 unique (void *array, size_t count, size_t size,
190 algo_compare_func *compare, const void *aux)
193 char *last = first + size * count;
194 char *result = array;
201 assert (adjacent_find_equal (array, count,
202 size, compare, aux) == NULL);
206 if (compare (result, first, aux))
210 memcpy (result, first, size);
217 /* Helper function that calls sort(), then unique(). */
219 sort_unique (void *array, size_t count, size_t size,
220 algo_compare_func *compare, const void *aux)
222 sort (array, count, size, compare, aux);
223 return unique (array, count, size, compare, aux);
226 /* Reorders ARRAY, which contains COUNT elements of SIZE bytes
227 each, so that the elements for which PREDICATE returns true
228 precede those for which PREDICATE returns zero. AUX is
229 passed to each predicate as auxiliary data. Returns the
230 number of elements for which PREDICATE returns true. Not
233 partition (void *array, size_t count, size_t size,
234 algo_predicate_func *predicate, const void *aux)
236 size_t true_cnt = count;
238 char *last = first + true_cnt * size;
242 /* Move FIRST forward to point to first element that fails
248 else if (!predicate (first, aux))
255 /* Move LAST backward to point to last element that passes
263 else if (predicate (last, aux))
269 /* By swapping FIRST and LAST we extend the starting and
270 ending sequences that pass and fail, respectively,
272 SWAP (first, last, size);
277 assert (is_partitioned (array, count, size, true_cnt, predicate, aux));
281 /* Checks whether ARRAY, which contains COUNT elements of SIZE
282 bytes each, is partitioned such that PREDICATE returns true
283 for the first TRUE_CNT elements and zero for the remaining
284 elements. AUX is passed as auxiliary data to PREDICATE. */
286 is_partitioned (const void *array, size_t count, size_t size,
288 algo_predicate_func *predicate, const void *aux)
290 const char *first = array;
293 assert (true_cnt <= count);
294 for (idx = 0; idx < true_cnt; idx++)
295 if (predicate (first + idx * size, aux) == 0)
297 for (idx = true_cnt; idx < count; idx++)
298 if (predicate (first + idx * size, aux) != 0)
303 /* Copies the COUNT elements of SIZE bytes each from ARRAY to
304 RESULT, except that elements for which PREDICATE is false are
305 not copied. Returns the number of elements copied. AUX is
306 passed to PREDICATE as auxiliary data. */
308 copy_if (const void *array, size_t count, size_t size,
310 algo_predicate_func *predicate, const void *aux)
312 const char *input = array;
313 const char *last = input + size * count;
314 char *output = result;
315 size_t nonzero_cnt = 0;
319 if (predicate (input, aux))
321 memcpy (output, input, size);
329 assert (nonzero_cnt == count_if (array, count, size, predicate, aux));
330 assert (nonzero_cnt == count_if (result, nonzero_cnt, size, predicate, aux));
335 /* Removes N elements starting at IDX from ARRAY, which consists
336 of COUNT elements of SIZE bytes each, by shifting the elements
337 following them, if any, into its position. */
339 remove_range (void *array_, size_t count, size_t size,
340 size_t idx, size_t n)
342 char *array = array_;
344 assert (array != NULL);
345 assert (idx <= count);
346 assert (idx + n <= count);
349 memmove (array + idx * size, array + (idx + n) * size,
350 size * (count - idx - n));
353 /* Removes element IDX from ARRAY, which consists of COUNT
354 elements of SIZE bytes each, by shifting the elements
355 following it, if any, into its position. */
357 remove_element (void *array, size_t count, size_t size,
360 remove_range (array, count, size, idx, 1);
363 /* Makes room for N elements starting at IDX in ARRAY, which
364 initially consists of COUNT elements of SIZE bytes each, by
365 shifting elements IDX...COUNT (exclusive) to the right by N
368 insert_range (void *array_, size_t count, size_t size,
369 size_t idx, size_t n)
371 char *array = array_;
373 assert (idx <= count);
374 memmove (array + (idx + n) * size, array + idx * size, (count - idx) * size);
377 /* Makes room for a new element at IDX in ARRAY, which initially
378 consists of COUNT elements of SIZE bytes each, by shifting
379 elements IDX...COUNT (exclusive) to the right by one
382 insert_element (void *array, size_t count, size_t size,
385 insert_range (array, count, size, idx, 1);
388 /* Moves an element in ARRAY, which consists of COUNT elements of
389 SIZE bytes each, from OLD_IDX to NEW_IDX, shifting around
390 other elements as needed. Runs in O(abs(OLD_IDX - NEW_IDX))
393 move_element (void *array_, size_t count, size_t size,
394 size_t old_idx, size_t new_idx)
396 assert (array_ != NULL || count == 0);
397 assert (old_idx < count);
398 assert (new_idx < count);
400 if (old_idx != new_idx)
402 char *array = array_;
403 char *element = xmalloc (size);
404 char *new = array + new_idx * size;
405 char *old = array + old_idx * size;
407 memcpy (element, old, size);
409 memmove (new + size, new, (old_idx - new_idx) * size);
411 memmove (old, old + size, (new_idx - old_idx) * size);
412 memcpy (new, element, size);
418 /* A predicate and its auxiliary data. */
421 algo_predicate_func *predicate;
426 not (const void *data, const void *pred_aux_)
428 const struct pred_aux *pred_aux = pred_aux_;
430 return !pred_aux->predicate (data, pred_aux->aux);
433 /* Removes elements equal to ELEMENT from ARRAY, which consists
434 of COUNT elements of SIZE bytes each. Returns the number of
435 remaining elements. AUX is passed to COMPARE as auxiliary
438 remove_equal (void *array, size_t count, size_t size,
440 algo_compare_func *compare, const void *aux)
443 char *last = first + count * size;
450 if (compare (first, element, aux) == 0)
464 if (compare (first, element, aux) == 0)
470 memcpy (result, first, size);
475 assert (count_equal (array, count, size, element, compare, aux) == 0);
479 /* Copies the COUNT elements of SIZE bytes each from ARRAY to
480 RESULT, except that elements for which PREDICATE is true are
481 not copied. Returns the number of elements copied. AUX is
482 passed to PREDICATE as auxiliary data. */
484 remove_copy_if (const void *array, size_t count, size_t size,
486 algo_predicate_func *predicate, const void *aux)
488 struct pred_aux pred_aux;
489 pred_aux.predicate = predicate;
491 return copy_if (array, count, size, result, not, &pred_aux);
494 /* Searches ARRAY, which contains COUNT of SIZE bytes each, using
495 a binary search. Returns any element that equals VALUE, if
496 one exists, or a null pointer otherwise. ARRAY must ordered
497 according to COMPARE. AUX is passed to COMPARE as auxiliary
500 binary_search (const void *array, size_t count, size_t size,
502 algo_compare_func *compare, const void *aux)
504 assert (array != NULL);
505 assert (count <= INT_MAX);
506 assert (compare != NULL);
510 const char *first = array;
512 int high = count - 1;
516 int middle = (low + high) / 2;
517 const char *element = first + middle * size;
518 int cmp = compare (value, element, aux);
525 return (void *) element;
529 expensive_assert (find (array, count, size, value, compare, aux) == NULL);
533 /* Lexicographically compares ARRAY1, which contains COUNT1
534 elements of SIZE bytes each, to ARRAY2, which contains COUNT2
535 elements of SIZE bytes, according to COMPARE. Returns a
536 strcmp()-type result. AUX is passed to COMPARE as auxiliary
539 lexicographical_compare_3way (const void *array1, size_t count1,
540 const void *array2, size_t count2,
542 algo_compare_func *compare, const void *aux)
544 const char *first1 = array1;
545 const char *first2 = array2;
546 size_t min_count = count1 < count2 ? count1 : count2;
548 while (min_count > 0)
550 int cmp = compare (first1, first2, aux);
559 return count1 < count2 ? -1 : count1 > count2;
562 /* If you consider tuning this algorithm, you should consult first:
563 Engineering a sort function; Jon Bentley and M. Douglas McIlroy;
564 Software - Practice and Experience; Vol. 23 (11), 1249-1265, 1993. */
570 /* Discontinue quicksort algorithm when partition gets below this size.
571 This particular magic number was chosen to work best on a Sun 4/260. */
574 /* Stack node declarations used to store unfulfilled partition obligations. */
581 /* The next 4 #defines implement a very fast in-line stack abstraction. */
582 /* The stack needs log (total_elements) entries (we could even subtract
583 log(MAX_THRESH)). Since total_elements has type size_t, we get as
584 upper bound for log (total_elements):
585 bits per byte (CHAR_BIT) * sizeof(size_t). */
586 #define STACK_SIZE (CHAR_BIT * sizeof(size_t))
587 #define PUSH(low, high) ((void) ((top->lo = (low)), (top->hi = (high)), ++top))
588 #define POP(low, high) ((void) (--top, (low = top->lo), (high = top->hi)))
589 #define STACK_NOT_EMPTY (stack < top)
592 /* Order size using quicksort. This implementation incorporates
593 four optimizations discussed in Sedgewick:
595 1. Non-recursive, using an explicit stack of pointer that store the
596 next array partition to sort. To save time, this maximum amount
597 of space required to store an array of SIZE_MAX is allocated on the
598 stack. Assuming a 32-bit (64 bit) integer for size_t, this needs
599 only 32 * sizeof(stack_node) == 256 bytes (for 64 bit: 1024 bytes).
600 Pretty cheap, actually.
602 2. Chose the pivot element using a median-of-three decision tree.
603 This reduces the probability of selecting a bad pivot value and
604 eliminates certain extraneous comparisons.
606 3. Only quicksorts TOTAL_ELEMS / MAX_THRESH partitions, leaving
607 insertion sort to order the MAX_THRESH items within each partition.
608 This is a big win, since insertion sort is faster for small, mostly
609 sorted array segments.
611 4. The larger of the two sub-partitions is always pushed onto the
612 stack first, with the algorithm then concentrating on the
613 smaller partition. This *guarantees* no more than log (total_elems)
614 stack size is needed (actually O(1) in this case)! */
617 sort (void *array, size_t count, size_t size,
618 algo_compare_func *compare, const void *aux)
620 char *const first = array;
621 const size_t max_thresh = MAX_THRESH * size;
624 /* Avoid lossage with unsigned arithmetic below. */
627 if (count > MAX_THRESH)
630 char *hi = &lo[size * (count - 1)];
631 stack_node stack[STACK_SIZE];
632 stack_node *top = stack + 1;
634 while (STACK_NOT_EMPTY)
639 /* Select median value from among LO, MID, and HI. Rearrange
640 LO and HI so the three values are sorted. This lowers the
641 probability of picking a pathological pivot value and
642 skips a comparison for both the LEFT_PTR and RIGHT_PTR in
645 char *mid = lo + size * ((hi - lo) / size >> 1);
647 if (compare (mid, lo, aux) < 0)
648 SWAP (mid, lo, size);
649 if (compare (hi, mid, aux) < 0)
650 SWAP (mid, hi, size);
653 if (compare (mid, lo, aux) < 0)
654 SWAP (mid, lo, size);
657 left_ptr = lo + size;
658 right_ptr = hi - size;
660 /* Here's the famous ``collapse the walls'' section of quicksort.
661 Gotta like those tight inner loops! They are the main reason
662 that this algorithm runs much faster than others. */
665 while (compare (left_ptr, mid, aux) < 0)
668 while (compare (mid, right_ptr, aux) < 0)
671 if (left_ptr < right_ptr)
673 SWAP (left_ptr, right_ptr, size);
676 else if (mid == right_ptr)
681 else if (left_ptr == right_ptr)
688 while (left_ptr <= right_ptr);
690 /* Set up pointers for next iteration. First determine whether
691 left and right partitions are below the threshold size. If so,
692 ignore one or both. Otherwise, push the larger partition's
693 bounds on the stack and continue sorting the smaller one. */
695 if ((size_t) (right_ptr - lo) <= max_thresh)
697 if ((size_t) (hi - left_ptr) <= max_thresh)
698 /* Ignore both small partitions. */
701 /* Ignore small left partition. */
704 else if ((size_t) (hi - left_ptr) <= max_thresh)
705 /* Ignore small right partition. */
707 else if ((right_ptr - lo) > (hi - left_ptr))
709 /* Push larger left partition indices. */
710 PUSH (lo, right_ptr);
715 /* Push larger right partition indices. */
722 /* Once the FIRST array is partially sorted by quicksort the rest
723 is completely sorted using insertion sort, since this is efficient
724 for partitions below MAX_THRESH size. FIRST points to the beginning
725 of the array to sort, and END_PTR points at the very last element in
726 the array (*not* one beyond it!). */
729 char *const end_ptr = &first[size * (count - 1)];
730 char *tmp_ptr = first;
731 char *thresh = MIN (end_ptr, first + max_thresh);
732 register char *run_ptr;
734 /* Find smallest element in first threshold and place it at the
735 array's beginning. This is the smallest array element,
736 and the operation speeds up insertion sort's inner loop. */
738 for (run_ptr = tmp_ptr + size; run_ptr <= thresh; run_ptr += size)
739 if (compare (run_ptr, tmp_ptr, aux) < 0)
742 if (tmp_ptr != first)
743 SWAP (tmp_ptr, first, size);
745 /* Insertion sort, running from left-hand-side up to right-hand-side. */
747 run_ptr = first + size;
748 while ((run_ptr += size) <= end_ptr)
750 tmp_ptr = run_ptr - size;
751 while (compare (run_ptr, tmp_ptr, aux) < 0)
755 if (tmp_ptr != run_ptr)
759 trav = run_ptr + size;
760 while (--trav >= run_ptr)
765 for (hi = lo = trav; (lo -= size) >= tmp_ptr; hi = lo)
773 assert (is_sorted (array, count, size, compare, aux));
776 /* Tests whether ARRAY, which contains COUNT elements of SIZE
777 bytes each, is sorted in order according to COMPARE. AUX is
778 passed to COMPARE as auxiliary data. */
780 is_sorted (const void *array, size_t count, size_t size,
781 algo_compare_func *compare, const void *aux)
783 const char *first = array;
786 for (idx = 0; idx + 1 < count; idx++)
787 if (compare (first + idx * size, first + (idx + 1) * size, aux) > 0)
793 /* Computes the generalized set difference, ARRAY1 minus ARRAY2,
794 into RESULT, and returns the number of elements written to
795 RESULT. If a value appears M times in ARRAY1 and N times in
796 ARRAY2, then it will appear max(M - N, 0) in RESULT. ARRAY1
797 and ARRAY2 must be sorted, and RESULT is sorted and stable.
798 ARRAY1 consists of COUNT1 elements, ARRAY2 of COUNT2 elements,
799 each SIZE bytes. AUX is passed to COMPARE as auxiliary
801 size_t set_difference (const void *array1, size_t count1,
802 const void *array2, size_t count2,
805 algo_compare_func *compare, const void *aux)
807 const char *first1 = array1;
808 const char *last1 = first1 + count1 * size;
809 const char *first2 = array2;
810 const char *last2 = first2 + count2 * size;
811 char *result = result_;
812 size_t result_count = 0;
814 while (first1 != last1 && first2 != last2)
816 int cmp = compare (first1, first2, aux);
819 memcpy (result, first1, size);
833 while (first1 != last1)
835 memcpy (result, first1, size);
844 /* Finds the first pair of adjacent equal elements in ARRAY,
845 which has COUNT elements of SIZE bytes. Returns the first
846 element in ARRAY such that COMPARE returns zero when it and
847 its successor element are compared, or a null pointer if no
848 such element exists. AUX is passed to COMPARE as auxiliary
851 adjacent_find_equal (const void *array, size_t count, size_t size,
852 algo_compare_func *compare, const void *aux)
854 const char *first = array;
855 const char *last = first + count * size;
857 while (first < last && first + size < last)
859 if (compare (first, first + size, aux) == 0)
860 return (void *) first;
867 /* ARRAY contains COUNT elements of SIZE bytes each. Initially
868 the first COUNT - 1 elements of these form a heap, followed by
869 a single element not part of the heap. This function adds the
870 final element, forming a heap of COUNT elements in ARRAY.
871 Uses COMPARE to compare elements, passing AUX as auxiliary
874 push_heap (void *array, size_t count, size_t size,
875 algo_compare_func *compare, const void *aux)
880 expensive_assert (count < 1 || is_heap (array, count - 1,
881 size, compare, aux));
882 for (i = count; i > 1; i /= 2)
884 char *parent = first + (i / 2 - 1) * size;
885 char *element = first + (i - 1) * size;
886 if (compare (parent, element, aux) < 0)
887 SWAP (parent, element, size);
891 expensive_assert (is_heap (array, count, size, compare, aux));
894 /* ARRAY contains COUNT elements of SIZE bytes each. Initially
895 the children of ARRAY[idx - 1] are heaps, but ARRAY[idx - 1]
896 may be smaller than its children. This function fixes that,
897 so that ARRAY[idx - 1] itself is a heap. Uses COMPARE to
898 compare elements, passing AUX as auxiliary data. */
900 heapify (void *array, size_t count, size_t size,
902 algo_compare_func *compare, const void *aux)
908 size_t left = 2 * idx;
909 size_t right = left + 1;
910 size_t largest = idx;
913 && compare (first + size * (left - 1),
914 first + size * (idx - 1), aux) > 0)
918 && compare (first + size * (right - 1),
919 first + size * (largest - 1), aux) > 0)
925 SWAP (first + size * (idx - 1), first + size * (largest - 1), size);
930 /* ARRAY contains COUNT elements of SIZE bytes each. Initially
931 all COUNT elements form a heap. This function moves the
932 largest element in the heap to the final position in ARRAY and
933 reforms a heap of the remaining COUNT - 1 elements at the
934 beginning of ARRAY. Uses COMPARE to compare elements, passing
935 AUX as auxiliary data. */
937 pop_heap (void *array, size_t count, size_t size,
938 algo_compare_func *compare, const void *aux)
942 expensive_assert (is_heap (array, count, size, compare, aux));
943 SWAP (first, first + (count - 1) * size, size);
944 heapify (first, count - 1, size, 1, compare, aux);
945 expensive_assert (count < 1 || is_heap (array, count - 1,
946 size, compare, aux));
949 /* Turns ARRAY, which contains COUNT elements of SIZE bytes, into
950 a heap. Uses COMPARE to compare elements, passing AUX as
953 make_heap (void *array, size_t count, size_t size,
954 algo_compare_func *compare, const void *aux)
958 for (idx = count / 2; idx >= 1; idx--)
959 heapify (array, count, size, idx, compare, aux);
960 expensive_assert (count < 1 || is_heap (array, count, size, compare, aux));
963 /* ARRAY contains COUNT elements of SIZE bytes each. Initially
964 all COUNT elements form a heap. This function turns the heap
965 into a fully sorted array. Uses COMPARE to compare elements,
966 passing AUX as auxiliary data. */
968 sort_heap (void *array, size_t count, size_t size,
969 algo_compare_func *compare, const void *aux)
974 expensive_assert (is_heap (array, count, size, compare, aux));
975 for (idx = count; idx >= 2; idx--)
977 SWAP (first, first + (idx - 1) * size, size);
978 heapify (array, idx - 1, size, 1, compare, aux);
980 expensive_assert (is_sorted (array, count, size, compare, aux));
983 /* ARRAY contains COUNT elements of SIZE bytes each. This
984 function tests whether ARRAY is a heap and returns true if so,
985 false otherwise. Uses COMPARE to compare elements, passing
986 AUX as auxiliary data. */
988 is_heap (const void *array, size_t count, size_t size,
989 algo_compare_func *compare, const void *aux)
991 const char *first = array;
994 for (child = 2; child <= count; child++)
996 size_t parent = child / 2;
997 if (compare (first + (parent - 1) * size,
998 first + (child - 1) * size, aux) < 0)