blob: 39b7a088520a61a87c1565474cb4b32ea6ce766a
| 1 | /* |
| 2 | * copyright (c) 2012 Michael Niedermayer <michaelni@gmx.at> |
| 3 | * |
| 4 | * This file is part of FFmpeg. |
| 5 | * |
| 6 | * FFmpeg is free software; you can redistribute it and/or |
| 7 | * modify it under the terms of the GNU Lesser General Public |
| 8 | * License as published by the Free Software Foundation; either |
| 9 | * version 2.1 of the License, or (at your option) any later version. |
| 10 | * |
| 11 | * FFmpeg is distributed in the hope that it will be useful, |
| 12 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 13 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| 14 | * Lesser General Public License for more details. |
| 15 | * |
| 16 | * You should have received a copy of the GNU Lesser General Public |
| 17 | * License along with FFmpeg; if not, write to the Free Software |
| 18 | * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA |
| 19 | */ |
| 20 | |
| 21 | #ifndef AVUTIL_QSORT_H |
| 22 | #define AVUTIL_QSORT_H |
| 23 | |
| 24 | #include "common.h" |
| 25 | |
| 26 | |
| 27 | /** |
| 28 | * Quicksort |
| 29 | * This sort is fast, and fully inplace but not stable and it is possible |
| 30 | * to construct input that requires O(n^2) time but this is very unlikely to |
| 31 | * happen with non constructed input. |
| 32 | */ |
| 33 | #define AV_QSORT(p, num, type, cmp) do {\ |
| 34 | void *stack[64][2];\ |
| 35 | int sp= 1;\ |
| 36 | stack[0][0] = p;\ |
| 37 | stack[0][1] = (p)+(num)-1;\ |
| 38 | while(sp){\ |
| 39 | type *start= stack[--sp][0];\ |
| 40 | type *end = stack[ sp][1];\ |
| 41 | while(start < end){\ |
| 42 | if(start < end-1) {\ |
| 43 | int checksort=0;\ |
| 44 | type *right = end-2;\ |
| 45 | type *left = start+1;\ |
| 46 | type *mid = start + ((end-start)>>1);\ |
| 47 | if(cmp(start, end) > 0) {\ |
| 48 | if(cmp( end, mid) > 0) FFSWAP(type, *start, *mid);\ |
| 49 | else FFSWAP(type, *start, *end);\ |
| 50 | }else{\ |
| 51 | if(cmp(start, mid) > 0) FFSWAP(type, *start, *mid);\ |
| 52 | else checksort= 1;\ |
| 53 | }\ |
| 54 | if(cmp(mid, end) > 0){ \ |
| 55 | FFSWAP(type, *mid, *end);\ |
| 56 | checksort=0;\ |
| 57 | }\ |
| 58 | if(start == end-2) break;\ |
| 59 | FFSWAP(type, end[-1], *mid);\ |
| 60 | while(left <= right){\ |
| 61 | while(left<=right && cmp(left, end-1) < 0)\ |
| 62 | left++;\ |
| 63 | while(left<=right && cmp(right, end-1) > 0)\ |
| 64 | right--;\ |
| 65 | if(left <= right){\ |
| 66 | FFSWAP(type, *left, *right);\ |
| 67 | left++;\ |
| 68 | right--;\ |
| 69 | }\ |
| 70 | }\ |
| 71 | FFSWAP(type, end[-1], *left);\ |
| 72 | if(checksort && (mid == left-1 || mid == left)){\ |
| 73 | mid= start;\ |
| 74 | while(mid<end && cmp(mid, mid+1) <= 0)\ |
| 75 | mid++;\ |
| 76 | if(mid==end)\ |
| 77 | break;\ |
| 78 | }\ |
| 79 | if(end-left < left-start){\ |
| 80 | stack[sp ][0]= start;\ |
| 81 | stack[sp++][1]= right;\ |
| 82 | start = left+1;\ |
| 83 | }else{\ |
| 84 | stack[sp ][0]= left+1;\ |
| 85 | stack[sp++][1]= end;\ |
| 86 | end = right;\ |
| 87 | }\ |
| 88 | }else{\ |
| 89 | if(cmp(start, end) > 0)\ |
| 90 | FFSWAP(type, *start, *end);\ |
| 91 | break;\ |
| 92 | }\ |
| 93 | }\ |
| 94 | }\ |
| 95 | } while (0) |
| 96 | |
| 97 | /** |
| 98 | * Merge sort, this sort requires a temporary buffer and is stable, its worst |
| 99 | * case time is O(n log n) |
| 100 | * @param p must be a lvalue pointer, this function may exchange it with tmp |
| 101 | * @param tmp must be a lvalue pointer, this function may exchange it with p |
| 102 | */ |
| 103 | #define AV_MSORT(p, tmp, num, type, cmp) do {\ |
| 104 | unsigned i, j, step;\ |
| 105 | for(step=1; step<(num); step+=step){\ |
| 106 | for(i=0; i<(num); i+=2*step){\ |
| 107 | unsigned a[2] = {i, i+step};\ |
| 108 | unsigned end = FFMIN(i+2*step, (num));\ |
| 109 | for(j=i; a[0]<i+step && a[1]<end; j++){\ |
| 110 | int idx= cmp(p+a[0], p+a[1]) > 0;\ |
| 111 | tmp[j] = p[ a[idx]++ ];\ |
| 112 | }\ |
| 113 | if(a[0]>=i+step) a[0] = a[1];\ |
| 114 | for(; j<end; j++){\ |
| 115 | tmp[j] = p[ a[0]++ ];\ |
| 116 | }\ |
| 117 | }\ |
| 118 | FFSWAP(type*, p, tmp);\ |
| 119 | }\ |
| 120 | } while (0) |
| 121 | |
| 122 | #endif /* AVUTIL_QSORT_H */ |
| 123 |