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dbea353b92
Bring back sort_priv, we have need for sorting with a caller argument. Signed-off-by: Zach Brown <zab@versity.com>
72 lines
2.0 KiB
C
72 lines
2.0 KiB
C
/*
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* A copy of sort() from upstream with a priv argument that's passed
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* to comparison, like list_sort().
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*/
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/* ------------------------ */
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/*
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* A fast, small, non-recursive O(nlog n) sort for the Linux kernel
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*
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* Jan 23 2005 Matt Mackall <mpm@selenic.com>
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*/
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/sort.h>
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#include <linux/slab.h>
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#include "sort_priv.h"
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/**
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* sort - sort an array of elements
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* @priv: caller's pointer to pass to comparison and swap functions
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* @base: pointer to data to sort
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* @num: number of elements
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* @size: size of each element
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* @cmp_func: pointer to comparison function
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* @swap_func: pointer to swap function or NULL
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*
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* This function does a heapsort on the given array. You may provide a
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* swap_func function optimized to your element type.
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*
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* Sorting time is O(n log n) both on average and worst-case. While
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* qsort is about 20% faster on average, it suffers from exploitable
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* O(n*n) worst-case behavior and extra memory requirements that make
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* it less suitable for kernel use.
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*/
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void sort_priv(void *priv, void *base, size_t num, size_t size,
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int (*cmp_func)(void *priv, const void *, const void *),
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void (*swap_func)(void *priv, void *, void *, int size))
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{
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/* pre-scale counters for performance */
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int i = (num/2 - 1) * size, n = num * size, c, r;
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/* heapify */
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for ( ; i >= 0; i -= size) {
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for (r = i; r * 2 + size < n; r = c) {
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c = r * 2 + size;
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if (c < n - size &&
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cmp_func(priv, base + c, base + c + size) < 0)
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c += size;
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if (cmp_func(priv, base + r, base + c) >= 0)
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break;
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swap_func(priv, base + r, base + c, size);
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}
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}
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/* sort */
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for (i = n - size; i > 0; i -= size) {
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swap_func(priv, base, base + i, size);
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for (r = 0; r * 2 + size < i; r = c) {
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c = r * 2 + size;
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if (c < i - size &&
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cmp_func(priv, base + c, base + c + size) < 0)
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c += size;
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if (cmp_func(priv, base + r, base + c) >= 0)
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break;
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swap_func(priv, base + r, base + c, size);
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}
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}
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}
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