/*
  * 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 "common.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 */