cregit-Linux how code gets into the kernel

Release 4.17 lib/sort.c

Directory: lib
// SPDX-License-Identifier: GPL-2.0
/*
 * A fast, small, non-recursive O(nlog n) sort for the Linux kernel
 *
 * Jan 23 2005  Matt Mackall <mpm@selenic.com>
 */


#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/types.h>
#include <linux/export.h>
#include <linux/sort.h>


static int alignment_ok(const void *base, int align) { return IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS) || ((unsigned long)base & (align - 1)) == 0; }

Contributors

PersonTokensPropCommitsCommitProp
Daniel Wagner36100.00%1100.00%
Total36100.00%1100.00%


static void u32_swap(void *a, void *b, int size) { u32 t = *(u32 *)a; *(u32 *)a = *(u32 *)b; *(u32 *)b = t; }

Contributors

PersonTokensPropCommitsCommitProp
Matt Mackall4998.00%150.00%
Adrian Bunk12.00%150.00%
Total50100.00%2100.00%


static void u64_swap(void *a, void *b, int size) { u64 t = *(u64 *)a; *(u64 *)a = *(u64 *)b; *(u64 *)b = t; }

Contributors

PersonTokensPropCommitsCommitProp
Daniel Wagner50100.00%1100.00%
Total50100.00%1100.00%


static void generic_swap(void *a, void *b, int size) { char t; do { t = *(char *)a; *(char *)a++ = *(char *)b; *(char *)b++ = t; } while (--size > 0); }

Contributors

PersonTokensPropCommitsCommitProp
Matt Mackall6498.46%150.00%
Adrian Bunk11.54%150.00%
Total65100.00%2100.00%

/** * sort - sort an array of elements * @base: pointer to data to sort * @num: number of elements * @size: size of each element * @cmp_func: pointer to comparison function * @swap_func: pointer to swap function or NULL * * This function does a heapsort on the given array. You may provide a * swap_func function optimized to your element type. * * Sorting time is O(n log n) both on average and worst-case. While * qsort is about 20% faster on average, it suffers from exploitable * O(n*n) worst-case behavior and extra memory requirements that make * it less suitable for kernel use. */
void sort(void *base, size_t num, size_t size, int (*cmp_func)(const void *, const void *), void (*swap_func)(void *, void *, int size)) { /* pre-scale counters for performance */ int i = (num/2 - 1) * size, n = num * size, c, r; if (!swap_func) { if (size == 4 && alignment_ok(base, 4)) swap_func = u32_swap; else if (size == 8 && alignment_ok(base, 8)) swap_func = u64_swap; else swap_func = generic_swap; } /* heapify */ for ( ; i >= 0; i -= size) { for (r = i; r * 2 + size < n; r = c) { c = r * 2 + size; if (c < n - size && cmp_func(base + c, base + c + size) < 0) c += size; if (cmp_func(base + r, base + c) >= 0) break; swap_func(base + r, base + c, size); } } /* sort */ for (i = n - size; i > 0; i -= size) { swap_func(base, base + i, size); for (r = 0; r * 2 + size < i; r = c) { c = r * 2 + size; if (c < i - size && cmp_func(base + c, base + c + size) < 0) c += size; if (cmp_func(base + r, base + c) >= 0) break; swap_func(base + r, base + c, size); } } }

Contributors

PersonTokensPropCommitsCommitProp
Matt Mackall27282.67%120.00%
Daniel Wagner3610.94%120.00%
keios103.04%120.00%
Fengguang Wu103.04%120.00%
Subbaiah Venkata10.30%120.00%
Total329100.00%5100.00%

EXPORT_SYMBOL(sort);

Overall Contributors

PersonTokensPropCommitsCommitProp
Matt Mackall39571.30%111.11%
Daniel Wagner12222.02%111.11%
Fengguang Wu111.99%111.11%
keios101.81%111.11%
Kostenzer Felix71.26%111.11%
Adrian Bunk50.90%111.11%
Rasmus Villemoes20.36%111.11%
Greg Kroah-Hartman10.18%111.11%
Subbaiah Venkata10.18%111.11%
Total554100.00%9100.00%
Directory: lib
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