/* PSPP - a program for statistical analysis.
Copyright (C) 1997-9, 2000, 2010, 2011 Free Software Foundation, Inc.
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see . */
/* Copyright (C) 2001 Free Software Foundation, Inc.
This file is part of the GNU ISO C++ Library. This library is free
software; you can redistribute it and/or modify it under the
terms of the GNU General Public License as published by the
Free Software Foundation; either version 2, or (at your option)
any later version.
This library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see .
As a special exception, you may use this file as part of a free software
library without restriction. Specifically, if other files instantiate
templates or use macros or inline functions from this file, or you compile
this file and link it with other files to produce an executable, this
file does not by itself cause the resulting executable to be covered by
the GNU General Public License. This exception does not however
invalidate any other reasons why the executable file might be covered by
the GNU General Public License. */
/*
*
* Copyright (c) 1994
* Hewlett-Packard Company
*
* Permission to use, copy, modify, distribute and sell this software
* and its documentation for any purpose is hereby granted without fee,
* provided that the above copyright notice appear in all copies and
* that both that copyright notice and this permission notice appear
* in supporting documentation. Hewlett-Packard Company makes no
* representations about the suitability of this software for any
* purpose. It is provided "as is" without express or implied warranty.
*
*
* Copyright (c) 1996
* Silicon Graphics Computer Systems, Inc.
*
* Permission to use, copy, modify, distribute and sell this software
* and its documentation for any purpose is hereby granted without fee,
* provided that the above copyright notice appear in all copies and
* that both that copyright notice and this permission notice appear
* in supporting documentation. Silicon Graphics makes no
* representations about the suitability of this software for any
* purpose. It is provided "as is" without express or implied warranty.
*/
/* Copyright (C) 1991, 1992, 1996, 1997, 1999 Free Software Foundation, Inc.
This file is part of the GNU C Library.
Written by Douglas C. Schmidt (schmidt@ics.uci.edu).
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library. If not, see
. */
#include
#include "array.h"
#include
#include
#include
#include
#include "libpspp/assertion.h"
#include "gl/xalloc.h"
#include "gl/minmax.h"
/* Finds an element in ARRAY, which contains COUNT elements of
SIZE bytes each, using COMPARE for comparisons. Returns the
first element in ARRAY that matches TARGET, or a null pointer
on failure. AUX is passed to each comparison as auxiliary
data. */
void *
find (const void *array, size_t count, size_t size,
const void *target,
algo_compare_func *compare, const void *aux)
{
const char *element = array;
while (count--> 0)
{
if (compare (target, element, aux) == 0)
return (void *) element;
element += size;
}
return NULL;
}
/* Counts and return the number of elements in ARRAY, which
contains COUNT elements of SIZE bytes each, which are equal to
ELEMENT as compared with COMPARE. AUX is passed as auxiliary
data to COMPARE. */
size_t
count_equal (const void *array, size_t count, size_t size,
const void *element,
algo_compare_func *compare, const void *aux)
{
const char *first = array;
size_t n_equals = 0;
while (count--> 0)
{
if (compare (element, first, aux) == 0)
n_equals++;
first += size;
}
return n_equals;
}
/* Counts and return the number of elements in ARRAY, which
contains COUNT elements of SIZE bytes each, for which
PREDICATE returns true. AUX is passed as auxiliary data to
PREDICATE. */
size_t
count_if (const void *array, size_t count, size_t size,
algo_predicate_func *predicate, const void *aux)
{
const char *first = array;
size_t n_trues = 0;
while (count--> 0)
{
if (predicate (first, aux) != 0)
n_trues++;
first += size;
}
return n_trues;
}
/* Byte-wise swap objects A and B, each SIZE bytes. */
static void
swap (void *a_, void *b_, size_t size)
{
uint8_t *a = a_;
uint8_t *b = b_;
while (size--> 0)
{
uint8_t tmp = *a;
*a++ = *b;
*b++ = tmp;
}
}
/* Makes the elements in ARRAY unique, by moving up duplicates,
and returns the new number of elements in the array. Sorted
arrays only. Arguments same as for sort() above. */
size_t
unique (void *array, size_t count, size_t size,
algo_compare_func *compare, const void *aux)
{
char *first = array;
char *last = first + size * count;
char *result = array;
for (;;)
{
first += size;
if (first>= last)
{
assert (adjacent_find_equal (array, count,
size, compare, aux) == NULL);
return count;
}
if (compare (result, first, aux))
{
result += size;
if (result != first)
memcpy (result, first, size);
}
else
count--;
}
}
/* Helper function that calls sort(), then unique(). */
size_t
sort_unique (void *array, size_t count, size_t size,
algo_compare_func *compare, const void *aux)
{
sort (array, count, size, compare, aux);
return unique (array, count, size, compare, aux);
}
/* Reorders ARRAY, which contains COUNT elements of SIZE bytes
each, so that the elements for which PREDICATE returns true
precede those for which PREDICATE returns zero. AUX is
passed to each predicate as auxiliary data. Returns the
number of elements for which PREDICATE returns true. Not
stable. */
size_t
partition (void *array, size_t count, size_t size,
algo_predicate_func *predicate, const void *aux)
{
size_t n_trues = count;
char *first = array;
char *last = first + n_trues * size;
for (;;)
{
/* Move FIRST forward to point to first element that fails
PREDICATE. */
for (;;)
{
if (first == last)
goto done;
else if (!predicate (first, aux))
break;
first += size;
}
n_trues--;
/* Move LAST backward to point to last element that passes
PREDICATE. */
for (;;)
{
last -= size;
if (first == last)
goto done;
else if (predicate (last, aux))
break;
else
n_trues--;
}
/* By swapping FIRST and LAST we extend the starting and
ending sequences that pass and fail, respectively,
PREDICATE. */
swap (first, last, size);
first += size;
}
done:
assert (is_partitioned (array, count, size, n_trues, predicate, aux));
return n_trues;
}
/* Checks whether ARRAY, which contains COUNT elements of SIZE
bytes each, is partitioned such that PREDICATE returns true
for the first TRUE_CNT elements and zero for the remaining
elements. AUX is passed as auxiliary data to PREDICATE. */
bool
is_partitioned (const void *array, size_t count, size_t size,
size_t n_trues,
algo_predicate_func *predicate, const void *aux)
{
const char *first = array;
size_t idx;
assert (n_trues <= count); for (idx = 0; idx < n_trues; idx++) if (predicate (first + idx * size, aux) == 0) return false; for (idx = n_trues; idx < count; idx++) if (predicate (first + idx * size, aux) != 0) return false; return true; } /* Copies the COUNT elements of SIZE bytes each from ARRAY to RESULT, except that elements for which PREDICATE is false are not copied. Returns the number of elements copied. AUX is passed to PREDICATE as auxiliary data. */ size_t copy_if (const void *array, size_t count, size_t size, void *result, algo_predicate_func *predicate, const void *aux) { const char *input = array; const char *last = input + size * count; char *output = result; size_t n_nonzeros = 0; while (input < last) { if (predicate (input, aux)) { memcpy (output, input, size); output += size; n_nonzeros++; } input += size; } assert (n_nonzeros == count_if (array, count, size, predicate, aux)); assert (n_nonzeros == count_if (result, n_nonzeros, size, predicate, aux)); return n_nonzeros; } /* Removes N elements starting at IDX from ARRAY, which consists of COUNT elements of SIZE bytes each, by shifting the elements following them, if any, into its position. */ void remove_range (void *array_, size_t count, size_t size, size_t idx, size_t n) { char *array = array_; assert (array != NULL); assert (idx <= count); assert (idx + n <= count); if (idx + n < count) memmove (array + idx * size, array + (idx + n) * size, size * (count - idx - n)); } /* Removes element IDX from ARRAY, which consists of COUNT elements of SIZE bytes each, by shifting the elements following it, if any, into its position. */ void remove_element (void *array, size_t count, size_t size, size_t idx) { remove_range (array, count, size, idx, 1); } /* Makes room for N elements starting at IDX in ARRAY, which initially consists of COUNT elements of SIZE bytes each, by shifting elements IDX...COUNT (exclusive) to the right by N positions. */ void insert_range (void *array_, size_t count, size_t size, size_t idx, size_t n) { char *array = array_; assert (idx <= count); memmove (array + (idx + n) * size, array + idx * size, (count - idx) * size); } /* Makes room for a new element at IDX in ARRAY, which initially consists of COUNT elements of SIZE bytes each, by shifting elements IDX...COUNT (exclusive) to the right by one position. */ void insert_element (void *array, size_t count, size_t size, size_t idx) { insert_range (array, count, size, idx, 1); } /* Moves an element in ARRAY, which consists of COUNT elements of SIZE bytes each, from OLD_IDX to NEW_IDX, shifting around other elements as needed. Runs in O(abs(OLD_IDX - NEW_IDX)) time. */ void move_element (void *array_, size_t count, size_t size, size_t old_idx, size_t new_idx) { assert (array_ != NULL || count == 0); assert (old_idx < count); assert (new_idx < count); if (old_idx != new_idx) { char *array = array_; char *element = xmalloc (size); char *new = array + new_idx * size; char *old = array + old_idx * size; memcpy (element, old, size); if (new < old) memmove (new + size, new, (old_idx - new_idx) * size); else memmove (old, old + size, (new_idx - old_idx) * size); memcpy (new, element, size); free (element); } } /* Moves N elements in ARRAY starting at OLD_IDX, which consists of COUNT elements of SIZE bytes each, so that they now start at NEW_IDX, shifting around other elements as needed. */ void move_range (void *array_, size_t count, size_t size, size_t old_idx, size_t new_idx, size_t n) { assert (array_ != NULL || count == 0); assert (n <= count); assert (old_idx + n <= count); assert (new_idx + n <= count); if (old_idx != new_idx && n> 0)
{
char *array = array_;
char *range = xmalloc (size * n);
char *new = array + new_idx * size;
char *old = array + old_idx * size;
memcpy (range, old, size * n);
if (new < old) memmove (new + size * n, new, (old_idx - new_idx) * size); else memmove (old, old + size * n, (new_idx - old_idx) * size); memcpy (new, range, size * n); free (range); } } /* A predicate and its auxiliary data. */ struct pred_aux { algo_predicate_func *predicate; const void *aux; }; static bool not (const void *data, const void *pred_aux_) { const struct pred_aux *pred_aux = pred_aux_; return !pred_aux->predicate (data, pred_aux->aux);
}
/* Removes elements equal to ELEMENT from ARRAY, which consists
of COUNT elements of SIZE bytes each. Returns the number of
remaining elements. AUX is passed to COMPARE as auxiliary
data. */
size_t
remove_equal (void *array, size_t count, size_t size,
void *element,
algo_compare_func *compare, const void *aux)
{
char *first = array;
char *last = first + count * size;
char *result;
for (;;)
{
if (first>= last)
goto done;
if (compare (first, element, aux) == 0)
break;
first += size;
}
result = first;
count--;
for (;;)
{
first += size;
if (first>= last)
goto done;
if (compare (first, element, aux) == 0)
{
count--;
continue;
}
memcpy (result, first, size);
result += size;
}
done:
assert (count_equal (array, count, size, element, compare, aux) == 0);
return count;
}
/* Copies the COUNT elements of SIZE bytes each from ARRAY to
RESULT, except that elements for which PREDICATE is true are
not copied. Returns the number of elements copied. AUX is
passed to PREDICATE as auxiliary data. */
size_t
remove_copy_if (const void *array, size_t count, size_t size,
void *result,
algo_predicate_func *predicate, const void *aux)
{
struct pred_aux pred_aux;
pred_aux.predicate = predicate;
pred_aux.aux = aux;
return copy_if (array, count, size, result, not, &pred_aux);
}
/* Searches ARRAY, which contains COUNT of SIZE bytes each, using
a binary search. Returns any element that equals VALUE, if
one exists, or a null pointer otherwise. ARRAY must ordered
according to COMPARE. AUX is passed to COMPARE as auxiliary
data. */
void *
binary_search (const void *array, size_t count, size_t size,
void *value,
algo_compare_func *compare, const void *aux)
{
assert (array != NULL || count == 0);
assert (count <= INT_MAX); assert (compare != NULL); if (count != 0) { const char *first = array; int low = 0; int high = count - 1; while (low <= high) { int middle = (low + high) / 2; const char *element = first + middle * size; int cmp = compare (value, element, aux); if (cmp> 0)
low = middle + 1;
else if (cmp < 0) high = middle - 1; else return (void *) element; } } expensive_assert (find (array, count, size, value, compare, aux) == NULL); return NULL; } /* Lexicographically compares ARRAY1, which contains COUNT1 elements of SIZE bytes each, to ARRAY2, which contains COUNT2 elements of SIZE bytes, according to COMPARE. Returns a strcmp()-type result. AUX is passed to COMPARE as auxiliary data. */ int lexicographical_compare_3way (const void *array1, size_t count1, const void *array2, size_t count2, size_t size, algo_compare_func *compare, const void *aux) { const char *first1 = array1; const char *first2 = array2; size_t min_count = count1 < count2 ? count1 : count2; while (min_count> 0)
{
int cmp = compare (first1, first2, aux);
if (cmp != 0)
return cmp;
first1 += size;
first2 += size;
min_count--;
}
return count1 < count2 ? -1 : count1> count2;
}
/* If you consider tuning this algorithm, you should consult first:
Engineering a sort function; Jon Bentley and M. Douglas McIlroy;
Software - Practice and Experience; Vol. 23 (11), 1249-1265, 1993. */
#include
#include
#include
/* Discontinue quicksort algorithm when partition gets below this size.
This particular magic number was chosen to work best on a Sun 4/260. */
#define MAX_THRESH 4
/* Stack node declarations used to store unfulfilled partition obligations. */
typedef struct
{
char *lo;
char *hi;
} stack_node;
/* The next 4 #defines implement a very fast in-line stack abstraction. */
/* The stack needs log (total_elements) entries (we could even subtract
log(MAX_THRESH)). Since total_elements has type size_t, we get as
upper bound for log (total_elements):
bits per byte (CHAR_BIT) * sizeof(size_t). */
#define STACK_SIZE (CHAR_BIT * sizeof(size_t))
#define PUSH(low, high) ((void) ((top->lo = (low)), (top->hi = (high)), ++top))
#define POP(low, high) ((void) (--top, (low = top->lo), (high = top->hi)))
#define STACK_NOT_EMPTY (stack < top) /* Order size using quicksort. This implementation incorporates four optimizations discussed in Sedgewick: 1. Non-recursive, using an explicit stack of pointer that store the next array partition to sort. To save time, this maximum amount of space required to store an array of SIZE_MAX is allocated on the stack. Assuming a 32-bit (64 bit) integer for size_t, this needs only 32 * sizeof(stack_node) == 256 bytes (for 64 bit: 1024 bytes). Pretty cheap, actually. 2. Chose the pivot element using a median-of-three decision tree. This reduces the probability of selecting a bad pivot value and eliminates certain extraneous comparisons. 3. Only quicksorts TOTAL_ELEMS / MAX_THRESH partitions, leaving insertion sort to order the MAX_THRESH items within each partition. This is a big win, since insertion sort is faster for small, mostly sorted array segments. 4. The larger of the two sub-partitions is always pushed onto the stack first, with the algorithm then concentrating on the smaller partition. This *guarantees* no more than log (total_elems) stack size is needed (actually O(1) in this case)! */ void sort (void *array, size_t count, size_t size, algo_compare_func *compare, const void *aux) { char *const first = array; const size_t max_thresh = MAX_THRESH * size; if (count == 0) /* Avoid lossage with unsigned arithmetic below. */ return; if (count> MAX_THRESH)
{
char *lo = first;
char *hi = &lo[size * (count - 1)];
stack_node stack[STACK_SIZE];
stack_node *top = stack + 1;
while (STACK_NOT_EMPTY)
{
char *left_ptr;
char *right_ptr;
/* Select median value from among LO, MID, and HI. Rearrange
LO and HI so the three values are sorted. This lowers the
probability of picking a pathological pivot value and
skips a comparison for both the LEFT_PTR and RIGHT_PTR in
the while loops. */
char *mid = lo + size * ((hi - lo) / size>> 1);
if (compare (mid, lo, aux) < 0) swap (mid, lo, size); if (compare (hi, mid, aux) < 0) swap (mid, hi, size); else goto jump_over; if (compare (mid, lo, aux) < 0) swap (mid, lo, size); jump_over:; left_ptr = lo + size; right_ptr = hi - size; /* Here's the famous ``collapse the walls'' section of quicksort. Gotta like those tight inner loops! They are the main reason that this algorithm runs much faster than others. */ do { while (compare (left_ptr, mid, aux) < 0) left_ptr += size; while (compare (mid, right_ptr, aux) < 0) right_ptr -= size; if (left_ptr < right_ptr) { swap (left_ptr, right_ptr, size); if (mid == left_ptr) mid = right_ptr; else if (mid == right_ptr) mid = left_ptr; left_ptr += size; right_ptr -= size; } else if (left_ptr == right_ptr) { left_ptr += size; right_ptr -= size; break; } } while (left_ptr <= right_ptr); /* Set up pointers for next iteration. First determine whether left and right partitions are below the threshold size. If so, ignore one or both. Otherwise, push the larger partition's bounds on the stack and continue sorting the smaller one. */ if ((size_t) (right_ptr - lo) <= max_thresh) { if ((size_t) (hi - left_ptr) <= max_thresh) /* Ignore both small partitions. */ POP (lo, hi); else /* Ignore small left partition. */ lo = left_ptr; } else if ((size_t) (hi - left_ptr) <= max_thresh) /* Ignore small right partition. */ hi = right_ptr; else if ((right_ptr - lo)> (hi - left_ptr))
{
/* Push larger left partition indices. */
PUSH (lo, right_ptr);
lo = left_ptr;
}
else
{
/* Push larger right partition indices. */
PUSH (left_ptr, hi);
hi = right_ptr;
}
}
}
/* Once the FIRST array is partially sorted by quicksort the rest
is completely sorted using insertion sort, since this is efficient
for partitions below MAX_THRESH size. FIRST points to the beginning
of the array to sort, and END_PTR points at the very last element in
the array (*not* one beyond it!). */
{
char *const end_ptr = &first[size * (count - 1)];
char *tmp_ptr = first;
char *thresh = MIN (end_ptr, first + max_thresh);
register char *run_ptr;
/* Find smallest element in first threshold and place it at the
array's beginning. This is the smallest array element,
and the operation speeds up insertion sort's inner loop. */
for (run_ptr = tmp_ptr + size; run_ptr <= thresh; run_ptr += size) if (compare (run_ptr, tmp_ptr, aux) < 0) tmp_ptr = run_ptr; if (tmp_ptr != first) swap (tmp_ptr, first, size); /* Insertion sort, running from left-hand-side up to right-hand-side. */ run_ptr = first + size; while ((run_ptr += size) <= end_ptr) { tmp_ptr = run_ptr - size; while (compare (run_ptr, tmp_ptr, aux) < 0) tmp_ptr -= size; tmp_ptr += size; if (tmp_ptr != run_ptr) { char *trav; trav = run_ptr + size; while (--trav>= run_ptr)
{
char c = *trav;
char *hi, *lo;
for (hi = lo = trav; (lo -= size)>= tmp_ptr; hi = lo)
*hi = *lo;
*hi = c;
}
}
}
}
assert (is_sorted (array, count, size, compare, aux));
}
/* Tests whether ARRAY, which contains COUNT elements of SIZE
bytes each, is sorted in order according to COMPARE. AUX is
passed to COMPARE as auxiliary data. */
bool
is_sorted (const void *array, size_t count, size_t size,
algo_compare_func *compare, const void *aux)
{
const char *first = array;
size_t idx;
for (idx = 0; idx + 1 < count; idx++) if (compare (first + idx * size, first + (idx + 1) * size, aux)> 0)
return false;
return true;
}
/* Computes the generalized set difference, ARRAY1 minus ARRAY2,
into RESULT, and returns the number of elements written to
RESULT. If a value appears M times in ARRAY1 and N times in
ARRAY2, then it will appear max(M - N, 0) in RESULT. ARRAY1
and ARRAY2 must be sorted, and RESULT is sorted and stable.
ARRAY1 consists of COUNT1 elements, ARRAY2 of COUNT2 elements,
each SIZE bytes. AUX is passed to COMPARE as auxiliary
data. */
size_t set_difference (const void *array1, size_t count1,
const void *array2, size_t count2,
size_t size,
void *result_,
algo_compare_func *compare, const void *aux)
{
const char *first1 = array1;
const char *last1 = first1 + count1 * size;
const char *first2 = array2;
const char *last2 = first2 + count2 * size;
char *result = result_;
size_t result_count = 0;
while (first1 != last1 && first2 != last2)
{
int cmp = compare (first1, first2, aux);
if (cmp < 0) { memcpy (result, first1, size); first1 += size; result += size; result_count++; } else if (cmp> 0)
first2 += size;
else
{
first1 += size;
first2 += size;
}
}
while (first1 != last1)
{
memcpy (result, first1, size);
first1 += size;
result += size;
result_count++;
}
return result_count;
}
/* Finds the first pair of adjacent equal elements in ARRAY,
which has COUNT elements of SIZE bytes. Returns the first
element in ARRAY such that COMPARE returns zero when it and
its successor element are compared, or a null pointer if no
such element exists. AUX is passed to COMPARE as auxiliary
data. */
void *
adjacent_find_equal (const void *array, size_t count, size_t size,
algo_compare_func *compare, const void *aux)
{
const char *first = array;
const char *last = first + count * size;
while (first < last && first + size < last) { if (compare (first, first + size, aux) == 0) return (void *) first; first += size; } return NULL; } /* ARRAY contains COUNT elements of SIZE bytes each. Initially the first COUNT - 1 elements of these form a heap, followed by a single element not part of the heap. This function adds the final element, forming a heap of COUNT elements in ARRAY. Uses COMPARE to compare elements, passing AUX as auxiliary data. */ void push_heap (void *array, size_t count, size_t size, algo_compare_func *compare, const void *aux) { char *first = array; size_t i; expensive_assert (count < 1 || is_heap (array, count - 1, size, compare, aux)); for (i = count; i> 1; i /= 2)
{
char *parent = first + (i / 2 - 1) * size;
char *element = first + (i - 1) * size;
if (compare (parent, element, aux) < 0) swap (parent, element, size); else break; } expensive_assert (is_heap (array, count, size, compare, aux)); } /* ARRAY contains COUNT elements of SIZE bytes each. Initially the children of ARRAY[idx - 1] are heaps, but ARRAY[idx - 1] may be smaller than its children. This function fixes that, so that ARRAY[idx - 1] itself is a heap. Uses COMPARE to compare elements, passing AUX as auxiliary data. */ static void heapify (void *array, size_t count, size_t size, size_t idx, algo_compare_func *compare, const void *aux) { char *first = array; for (;;) { size_t left = 2 * idx; size_t right = left + 1; size_t largest = idx; if (left <= count && compare (first + size * (left - 1), first + size * (idx - 1), aux)> 0)
largest = left;
if (right <= count && compare (first + size * (right - 1), first + size * (largest - 1), aux)> 0)
largest = right;
if (largest == idx)
break;
swap (first + size * (idx - 1), first + size * (largest - 1), size);
idx = largest;
}
}
/* ARRAY contains COUNT elements of SIZE bytes each. Initially
all COUNT elements form a heap. This function moves the
largest element in the heap to the final position in ARRAY and
reforms a heap of the remaining COUNT - 1 elements at the
beginning of ARRAY. Uses COMPARE to compare elements, passing
AUX as auxiliary data. */
void
pop_heap (void *array, size_t count, size_t size,
algo_compare_func *compare, const void *aux)
{
char *first = array;
expensive_assert (is_heap (array, count, size, compare, aux));
swap (first, first + (count - 1) * size, size);
heapify (first, count - 1, size, 1, compare, aux);
expensive_assert (count < 1 || is_heap (array, count - 1, size, compare, aux)); } /* Turns ARRAY, which contains COUNT elements of SIZE bytes, into a heap. Uses COMPARE to compare elements, passing AUX as auxiliary data. */ void make_heap (void *array, size_t count, size_t size, algo_compare_func *compare, const void *aux) { size_t idx; for (idx = count / 2; idx>= 1; idx--)
heapify (array, count, size, idx, compare, aux);
expensive_assert (count < 1 || is_heap (array, count, size, compare, aux)); } /* ARRAY contains COUNT elements of SIZE bytes each. Initially all COUNT elements form a heap. This function turns the heap into a fully sorted array. Uses COMPARE to compare elements, passing AUX as auxiliary data. */ void sort_heap (void *array, size_t count, size_t size, algo_compare_func *compare, const void *aux) { char *first = array; size_t idx; expensive_assert (is_heap (array, count, size, compare, aux)); for (idx = count; idx>= 2; idx--)
{
swap (first, first + (idx - 1) * size, size);
heapify (array, idx - 1, size, 1, compare, aux);
}
expensive_assert (is_sorted (array, count, size, compare, aux));
}
/* ARRAY contains COUNT elements of SIZE bytes each. This
function tests whether ARRAY is a heap and returns true if so,
false otherwise. Uses COMPARE to compare elements, passing
AUX as auxiliary data. */
bool
is_heap (const void *array, size_t count, size_t size,
algo_compare_func *compare, const void *aux)
{
const char *first = array;
size_t child;
for (child = 2; child <= count; child++)
{
size_t parent = child / 2;
if (compare (first + (parent - 1) * size,
first + (child - 1) * size, aux) < 0)
return false;
}
return true;
}
/* Reverses the order of ARRAY, which contains COUNT elements of SIZE bytes
each. */
void
reverse_array (void *array_, size_t count, size_t size)
{
uint8_t *array = array_;
uint8_t *first = array;
uint8_t *last = array + (count - 1) * size;
for (size_t i = 0; i < count / 2; i++)
{
swap (first, last, size);
first += size;
last -= size;
}
}