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122 lines
4.2 KiB
122 lines
4.2 KiB
/* |
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* copyright (c) 2012 Michael Niedermayer <michaelni@gmx.at> |
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* |
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* This file is part of FFmpeg. |
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* |
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* FFmpeg is free software; you can redistribute it and/or |
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* modify it under the terms of the GNU Lesser General Public |
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* License as published by the Free Software Foundation; either |
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* version 2.1 of the License, or (at your option) any later version. |
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* |
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* FFmpeg is distributed in the hope that it will be useful, |
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* but WITHOUT ANY WARRANTY; without even the implied warranty of |
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
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* Lesser General Public License for more details. |
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* |
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* You should have received a copy of the GNU Lesser General Public |
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* License along with FFmpeg; if not, write to the Free Software |
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA |
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*/ |
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#ifndef AVUTIL_QSORT_H |
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#define AVUTIL_QSORT_H |
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#include "common.h" |
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/** |
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* Quicksort |
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* This sort is fast, and fully inplace but not stable and it is possible |
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* to construct input that requires O(n^2) time but this is very unlikely to |
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* happen with non constructed input. |
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*/ |
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#define AV_QSORT(p, num, type, cmp) do {\ |
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void *stack[64][2];\ |
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int sp= 1;\ |
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stack[0][0] = p;\ |
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stack[0][1] = (p)+(num)-1;\ |
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while(sp){\ |
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type *start= stack[--sp][0];\ |
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type *end = stack[ sp][1];\ |
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while(start < end){\ |
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if(start < end-1) {\ |
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int checksort=0;\ |
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type *right = end-2;\ |
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type *left = start+1;\ |
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type *mid = start + ((end-start)>>1);\ |
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if(cmp(start, end) > 0) {\ |
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if(cmp( end, mid) > 0) FFSWAP(type, *start, *mid);\ |
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else FFSWAP(type, *start, *end);\ |
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}else{\ |
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if(cmp(start, mid) > 0) FFSWAP(type, *start, *mid);\ |
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else checksort= 1;\ |
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}\ |
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if(cmp(mid, end) > 0){ \ |
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FFSWAP(type, *mid, *end);\ |
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checksort=0;\ |
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}\ |
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if(start == end-2) break;\ |
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FFSWAP(type, end[-1], *mid);\ |
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while(left <= right){\ |
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while(left<=right && cmp(left, end-1) < 0)\ |
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left++;\ |
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while(left<=right && cmp(right, end-1) > 0)\ |
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right--;\ |
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if(left <= right){\ |
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FFSWAP(type, *left, *right);\ |
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left++;\ |
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right--;\ |
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}\ |
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}\ |
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FFSWAP(type, end[-1], *left);\ |
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if(checksort && (mid == left-1 || mid == left)){\ |
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mid= start;\ |
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while(mid<end && cmp(mid, mid+1) <= 0)\ |
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mid++;\ |
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if(mid==end)\ |
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break;\ |
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}\ |
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if(end-left < left-start){\ |
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stack[sp ][0]= start;\ |
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stack[sp++][1]= right;\ |
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start = left+1;\ |
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}else{\ |
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stack[sp ][0]= left+1;\ |
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stack[sp++][1]= end;\ |
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end = right;\ |
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}\ |
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}else{\ |
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if(cmp(start, end) > 0)\ |
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FFSWAP(type, *start, *end);\ |
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break;\ |
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}\ |
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}\ |
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}\ |
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} while (0) |
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/** |
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* Merge sort, this sort requires a temporary buffer and is stable, its worst |
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* case time is O(n log n) |
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* @param p must be a lvalue pointer, this function may exchange it with tmp |
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* @param tmp must be a lvalue pointer, this function may exchange it with p |
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*/ |
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#define AV_MSORT(p, tmp, num, type, cmp) do {\ |
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unsigned i, j, step;\ |
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for(step=1; step<(num); step+=step){\ |
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for(i=0; i<(num); i+=2*step){\ |
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unsigned a[2] = {i, i+step};\ |
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unsigned end = FFMIN(i+2*step, (num));\ |
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for(j=i; a[0]<i+step && a[1]<end; j++){\ |
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int idx= cmp(p+a[0], p+a[1]) > 0;\ |
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tmp[j] = p[ a[idx]++ ];\ |
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}\ |
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if(a[0]>=i+step) a[0] = a[1];\ |
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for(; j<end; j++){\ |
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tmp[j] = p[ a[0]++ ];\ |
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}\ |
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}\ |
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FFSWAP(type*, p, tmp);\ |
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}\ |
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} while (0) |
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#endif /* AVUTIL_QSORT_H */
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