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Update heapsort() from OpenBSD

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This commit is contained in:
Guillem Jover 2018-05-21 01:34:17 +02:00
parent 21edbb4f22
commit a6f407ab0d
1 changed files with 5 additions and 4 deletions
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9
src/heapsort.c
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@ -1,3 +1,4 @@
/* $OpenBSD: heapsort.c,v 1.11 2017/05/20 12:48:56 millert Exp $ */
/*- /*-
* Copyright (c) 1991, 1993 * Copyright (c) 1991, 1993
* The Regents of the University of California. All rights reserved. * The Regents of the University of California. All rights reserved.
@ -64,7 +65,7 @@
* Build the list into a heap, where a heap is defined such that for * Build the list into a heap, where a heap is defined such that for
* the records K1 ... KN, Kj/2 >= Kj for 1 <= j/2 <= j <= N. * the records K1 ... KN, Kj/2 >= Kj for 1 <= j/2 <= j <= N.
* *
* There two cases. If j == nmemb, select largest of Ki and Kj. If * There are two cases. If j == nmemb, select largest of Ki and Kj. If
* j < nmemb, select largest of Ki, Kj and Kj+1. * j < nmemb, select largest of Ki, Kj and Kj+1.
*/ */
#define CREATE(initval, nmemb, par_i, child_i, par, child, size, count, tmp) { \ #define CREATE(initval, nmemb, par_i, child_i, par, child, size, count, tmp) { \
@ -86,12 +87,12 @@
* Select the top of the heap and 'heapify'. Since by far the most expensive * Select the top of the heap and 'heapify'. Since by far the most expensive
* action is the call to the compar function, a considerable optimization * action is the call to the compar function, a considerable optimization
* in the average case can be achieved due to the fact that k, the displaced * in the average case can be achieved due to the fact that k, the displaced
* elememt, is usually quite small, so it would be preferable to first * element, is usually quite small, so it would be preferable to first
* heapify, always maintaining the invariant that the larger child is copied * heapify, always maintaining the invariant that the larger child is copied
* over its parent's record. * over its parent's record.
* *
* Then, starting from the *bottom* of the heap, finding k's correct place, * Then, starting from the *bottom* of the heap, finding k's correct place,
* again maintianing the invariant. As a result of the invariant no element * again maintaining the invariant. As a result of the invariant no element
* is 'lost' when k is assigned its correct place in the heap. * is 'lost' when k is assigned its correct place in the heap.
* *
* The time savings from this optimization are on the order of 15-20% for the * The time savings from this optimization are on the order of 15-20% for the
@ -131,7 +132,7 @@
*/ */
int int
heapsort(void *vbase, size_t nmemb, size_t size, heapsort(void *vbase, size_t nmemb, size_t size,
int (*compar)(const void *, const void *)) int (*compar)(const void *, const void *))
{ {
size_t cnt, i, j, l; size_t cnt, i, j, l;
char tmp, *tmp1, *tmp2; char tmp, *tmp1, *tmp2;