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sortix--sortix/libc/stdlib/qsort.cpp
2013-12-17 14:30:37 +01:00

61 lines
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C++

/*******************************************************************************
Copyright(C) Jonas 'Sortie' Termansen 2012.
This file is part of the Sortix C Library.
The Sortix 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 3 of the License, or (at your
option) any later version.
The Sortix 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 Sortix C Library. If not, see <http://www.gnu.org/licenses/>.
stdlib/qsort.cpp
Utility functions related to sorting and sorted data.
*******************************************************************************/
#include <stdint.h>
#include <stdlib.h>
#include <string.h>
// TODO: This is an ugly hack!
static void memswap(uint8_t* a, uint8_t* b, size_t size)
{
uint8_t* tmp = (uint8_t*) malloc(size);
if ( !tmp ) { abort(); }
memcpy(tmp, a, size);
memcpy(a, b, size);
memcpy(b, tmp, size);
free(tmp);
}
// TODO: This is just a quick and dirty insertion sort. It'd be nice to have a
// good old quick sort here soon. Combined with the slow memswap above, this
// results in a very slow sorting algorithm.
extern "C" void qsort(void* base, size_t nmemb, size_t size,
int (* compare)(const void*, const void*))
{
uint8_t* buf = (uint8_t*) base;
for ( size_t i = 0; i < nmemb; i++ )
{
for ( size_t c = i; c; c-- )
{
size_t currentoff = c * size;
uint8_t* current = buf + currentoff;
size_t p = c-1;
size_t prevoff = p * size;
uint8_t* prev = buf + prevoff;
int cmp = compare(prev, current);
if ( cmp <= 0 ) { break; }
memswap(prev, current, size);
}
}
}