sortix-mirror/libmaxsi/sort.cpp

63 lines
1.9 KiB
C++

/*******************************************************************************
COPYRIGHT(C) JONAS 'SORTIE' TERMANSEN 2012.
This file is part of LibMaxsi.
LibMaxsi 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.
LibMaxsi 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 LibMaxsi. If not, see <http://www.gnu.org/licenses/>.
sort.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);
}
}
}