The Tor Browser: intl/icu/source/common/uarrsort.c@b8a032363ba2 (annotated)

intl/icu/source/common/uarrsort.c@b8a032363ba2 (annotated)

intl/icu/source/common/uarrsort.c

Thu, 22 Jan 2015 13:21:57 +0100

author: Michael Schloh von Bennewitz <michael@schloh.com>
date: Thu, 22 Jan 2015 13:21:57 +0100
branch: TOR_BUG_9701
changeset 15: b8a032363ba2
permissions: -rw-r--r--

Incorporate requested changes from Mozilla in review:
https://bugzilla.mozilla.org/show_bug.cgi?id=1123480#c6

 /*
 *******************************************************************************
 *
 *   Copyright (C) 2003-2013, International Business Machines
 *   Corporation and others.  All Rights Reserved.
 *
 *******************************************************************************
 *   file name:  uarrsort.c
 *   encoding:   US-ASCII
 *   tab size:   8 (not used)
 *   indentation:4
 *
 *   created on: 2003aug04
 *   created by: Markus W. Scherer
 *
 *   Internal function for sorting arrays.
 */
 #include "unicode/utypes.h"
 #include "cmemory.h"
 #include "uarrsort.h"
 enum {
     /**
      * "from Knuth"
      *
      * A binary search over 8 items performs 4 comparisons:
      * log2(8)=3 to subdivide, +1 to check for equality.
      * A linear search over 8 items on average also performs 4 comparisons.
      */
     MIN_QSORT=9,
     STACK_ITEM_SIZE=200
 };
 /* UComparator convenience implementations ---------------------------------- */
 U_CAPI int32_t U_EXPORT2
 uprv_uint16Comparator(const void *context, const void *left, const void *right) {
     return (int32_t)*(const uint16_t *)left - (int32_t)*(const uint16_t *)right;
 }
 U_CAPI int32_t U_EXPORT2
 uprv_int32Comparator(const void *context, const void *left, const void *right) {
     return *(const int32_t *)left - *(const int32_t *)right;
 }
 U_CAPI int32_t U_EXPORT2
 uprv_uint32Comparator(const void *context, const void *left, const void *right) {
     uint32_t l=*(const uint32_t *)left, r=*(const uint32_t *)right;
     /* compare directly because (l-r) would overflow the int32_t result */
     if(l<r) {
         return -1;
     } else if(l==r) {
         return 0;
     } else /* l>r */ {
         return 1;
     }
 }
 /* Insertion sort using binary search --------------------------------------- */
 U_CAPI int32_t U_EXPORT2
 uprv_stableBinarySearch(char *array, int32_t limit, void *item, int32_t itemSize,
                         UComparator *cmp, const void *context) {
     int32_t start=0;
     UBool found=FALSE;
     /* Binary search until we get down to a tiny sub-array. */
     while((limit-start)>=MIN_QSORT) {
         int32_t i=(start+limit)/2;
         int32_t diff=cmp(context, item, array+i*itemSize);
         if(diff==0) {
             /*
              * Found the item. We look for the *last* occurrence of such
              * an item, for stable sorting.
              * If we knew that there will be only few equal items,
              * we could break now and enter the linear search.
              * However, if there are many equal items, then it should be
              * faster to continue with the binary search.
              * It seems likely that we either have all unique items
              * (where found will never become TRUE in the insertion sort)
              * or potentially many duplicates.
              */
             found=TRUE;
             start=i+1;
         } else if(diff<0) {
             limit=i;
         } else {
             start=i;
         }
     }
     /* Linear search over the remaining tiny sub-array. */
     while(start<limit) {
         int32_t diff=cmp(context, item, array+start*itemSize);
         if(diff==0) {
             found=TRUE;
         } else if(diff<0) {
             break;
         }
         ++start;
     }
     return found ? (start-1) : ~start;
 }
 static void
 doInsertionSort(char *array, int32_t length, int32_t itemSize,
                 UComparator *cmp, const void *context, void *pv) {
     int32_t j;
     for(j=1; j<length; ++j) {
         char *item=array+j*itemSize;
         int32_t insertionPoint=uprv_stableBinarySearch(array, j, item, itemSize, cmp, context);
         if(insertionPoint<0) {
             insertionPoint=~insertionPoint;
         } else {
             ++insertionPoint;  /* one past the last equal item */
         }
         if(insertionPoint<j) {
             char *dest=array+insertionPoint*itemSize;
             uprv_memcpy(pv, item, itemSize);  /* v=array[j] */
             uprv_memmove(dest+itemSize, dest, (j-insertionPoint)*itemSize);
             uprv_memcpy(dest, pv, itemSize);  /* array[insertionPoint]=v */
         }
     }
 }
 static void
 insertionSort(char *array, int32_t length, int32_t itemSize,
               UComparator *cmp, const void *context, UErrorCode *pErrorCode) {
     UAlignedMemory v[STACK_ITEM_SIZE/sizeof(UAlignedMemory)+1];
     void *pv;
     /* allocate an intermediate item variable (v) */
     if(itemSize<=STACK_ITEM_SIZE) {
         pv=v;
     } else {
         pv=uprv_malloc(itemSize);
         if(pv==NULL) {
             *pErrorCode=U_MEMORY_ALLOCATION_ERROR;
             return;
         }
     }
     doInsertionSort(array, length, itemSize, cmp, context, pv);
     if(pv!=v) {
         uprv_free(pv);
     }
 }
 /* QuickSort ---------------------------------------------------------------- */
 /*
  * This implementation is semi-recursive:
  * It recurses for the smaller sub-array to shorten the recursion depth,
  * and loops for the larger sub-array.
  *
  * Loosely after QuickSort algorithms in
  * Niklaus Wirth
  * Algorithmen und Datenstrukturen mit Modula-2
  * B.G. Teubner Stuttgart
  * 4. Auflage 1986
  * ISBN 3-519-02260-5
  */
 static void
 subQuickSort(char *array, int32_t start, int32_t limit, int32_t itemSize,
              UComparator *cmp, const void *context,
              void *px, void *pw) {
     int32_t left, right;
     /* start and left are inclusive, limit and right are exclusive */
     do {
         if((start+MIN_QSORT)>=limit) {
             doInsertionSort(array+start*itemSize, limit-start, itemSize, cmp, context, px);
             break;
         }
         left=start;
         right=limit;
         /* x=array[middle] */
         uprv_memcpy(px, array+((start+limit)/2)*itemSize, itemSize);
         do {
             while(/* array[left]<x */
                   cmp(context, array+left*itemSize, px)<0
             ) {
                 ++left;
             }
             while(/* x<array[right-1] */
                   cmp(context, px, array+(right-1)*itemSize)<0
             ) {
                 --right;
             }
             /* swap array[left] and array[right-1] via w; ++left; --right */
             if(left<right) {
                 --right;
                 if(left<right) {
                     uprv_memcpy(pw, array+left*itemSize, itemSize);
                     uprv_memcpy(array+left*itemSize, array+right*itemSize, itemSize);
                     uprv_memcpy(array+right*itemSize, pw, itemSize);
                 }
                 ++left;
             }
         } while(left<right);
         /* sort sub-arrays */
         if((right-start)<(limit-left)) {
             /* sort [start..right[ */
             if(start<(right-1)) {
                 subQuickSort(array, start, right, itemSize, cmp, context, px, pw);
             }
             /* sort [left..limit[ */
             start=left;
         } else {
             /* sort [left..limit[ */
             if(left<(limit-1)) {
                 subQuickSort(array, left, limit, itemSize, cmp, context, px, pw);
             }
             /* sort [start..right[ */
             limit=right;
         }
     } while(start<(limit-1));
 }
 static void
 quickSort(char *array, int32_t length, int32_t itemSize,
             UComparator *cmp, const void *context, UErrorCode *pErrorCode) {
     UAlignedMemory xw[(2*STACK_ITEM_SIZE)/sizeof(UAlignedMemory)+1];
     void *p;
     /* allocate two intermediate item variables (x and w) */
     if(itemSize<=STACK_ITEM_SIZE) {
         p=xw;
     } else {
         p=uprv_malloc(2*itemSize);
         if(p==NULL) {
             *pErrorCode=U_MEMORY_ALLOCATION_ERROR;
             return;
         }
     }
     subQuickSort(array, 0, length, itemSize,
                  cmp, context, p, (char *)p+itemSize);
     if(p!=xw) {
         uprv_free(p);
     }
 }
 /* uprv_sortArray() API ----------------------------------------------------- */
 /*
  * Check arguments, select an appropriate implementation,
  * cast the array to char * so that array+i*itemSize works.
  */
 U_CAPI void U_EXPORT2
 uprv_sortArray(void *array, int32_t length, int32_t itemSize,
                UComparator *cmp, const void *context,
                UBool sortStable, UErrorCode *pErrorCode) {
     if(pErrorCode==NULL || U_FAILURE(*pErrorCode)) {
         return;
     }
     if((length>0 && array==NULL) || length<0 || itemSize<=0 || cmp==NULL) {
         *pErrorCode=U_ILLEGAL_ARGUMENT_ERROR;
         return;
     }
     if(length<=1) {
         return;
     } else if(length<MIN_QSORT || sortStable) {
         insertionSort((char *)array, length, itemSize, cmp, context, pErrorCode);
     } else {
         quickSort((char *)array, length, itemSize, cmp, context, pErrorCode);
     }
 }

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intl/icu/source/common/uarrsort.c@b8a032363ba2 (annotated)

intl/icu/source/common/uarrsort.c