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/*
* copyright (c) 2012 Michael Niedermayer <michaelni@gmx.at>
*
* This file is part of FFmpeg.
*
* FFmpeg 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 2.1 of the License, or (at your option) any later version.
*
* FFmpeg 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 FFmpeg; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#ifndef AVUTIL_QSORT_H
#define AVUTIL_QSORT_H
#include "macros.h"
/**
* Quicksort
* This sort is fast, and fully inplace but not stable and it is possible
* to construct input that requires O(n^2) time but this is very unlikely to
* happen with non constructed input.
*/
#define AV_QSORT(p, num, type, cmp) do {\
void *stack[64][2];\
int sp= 1;\
stack[0][0] = p;\
stack[0][1] = (p)+(num)-1;\
while(sp){\
type *start= stack[--sp][0];\
type *end = stack[ sp][1];\
while(start < end){\
if(start < end-1) {\
int checksort=0;\
type *right = end-2;\
type *left = start+1;\
type *mid = start + ((end-start)>>1);\
if(cmp(start, end) > 0) {\
if(cmp( end, mid) > 0) FFSWAP(type, *start, *mid);\
else FFSWAP(type, *start, *end);\
}else{\
if(cmp(start, mid) > 0) FFSWAP(type, *start, *mid);\
else checksort= 1;\
}\
if(cmp(mid, end) > 0){ \
FFSWAP(type, *mid, *end);\
checksort=0;\
}\
if(start == end-2) break;\
FFSWAP(type, end[-1], *mid);\
while(left <= right){\
while(left<=right && cmp(left, end-1) < 0)\
left++;\
while(left<=right && cmp(right, end-1) > 0)\
right--;\
if(left <= right){\
FFSWAP(type, *left, *right);\
left++;\
right--;\
}\
}\
FFSWAP(type, end[-1], *left);\
if(checksort && (mid == left-1 || mid == left)){\
mid= start;\
while(mid<end && cmp(mid, mid+1) <= 0)\
mid++;\
if(mid==end)\
break;\
}\
if(end-left < left-start){\
stack[sp ][0]= start;\
stack[sp++][1]= right;\
start = left+1;\
}else{\
stack[sp ][0]= left+1;\
stack[sp++][1]= end;\
end = right;\
}\
}else{\
if(cmp(start, end) > 0)\
FFSWAP(type, *start, *end);\
break;\
}\
}\
}\
} while (0)
/**
* Merge sort, this sort requires a temporary buffer and is stable, its worst
* case time is O(n log n)
* @param p must be a lvalue pointer, this function may exchange it with tmp
* @param tmp must be a lvalue pointer, this function may exchange it with p
*/
#define AV_MSORT(p, tmp, num, type, cmp) do {\
unsigned i, j, step;\
for(step=1; step<(num); step+=step){\
for(i=0; i<(num); i+=2*step){\
unsigned a[2] = {i, i+step};\
unsigned end = FFMIN(i+2*step, (num));\
for(j=i; a[0]<i+step && a[1]<end; j++){\
int idx= cmp(p+a[0], p+a[1]) > 0;\
tmp[j] = p[ a[idx]++ ];\
}\
if(a[0]>=i+step) a[0] = a[1];\
for(; j<end; j++){\
tmp[j] = p[ a[0]++ ];\
}\
}\
FFSWAP(type*, p, tmp);\
}\
} while (0)
#endif /* AVUTIL_QSORT_H */
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