1 // Copyright (C) 2016 and later: Unicode, Inc. and others.
2 // License & terms of use: http://www.unicode.org/copyright.html
4 *******************************************************************************
6 * Copyright (C) 2003-2013, International Business Machines
7 * Corporation and others. All Rights Reserved.
9 *******************************************************************************
10 * file name: uarrsort.c
12 * tab size: 8 (not used)
15 * created on: 2003aug04
16 * created by: Markus W. Scherer
18 * Internal function for sorting arrays.
21 #include "unicode/utypes.h"
29 * A binary search over 8 items performs 4 comparisons:
30 * log2(8)=3 to subdivide, +1 to check for equality.
31 * A linear search over 8 items on average also performs 4 comparisons.
37 /* UComparator convenience implementations ---------------------------------- */
39 U_CAPI int32_t U_EXPORT2
40 uprv_uint16Comparator(const void *context, const void *left, const void *right) {
41 return (int32_t)*(const uint16_t *)left - (int32_t)*(const uint16_t *)right;
44 U_CAPI int32_t U_EXPORT2
45 uprv_int32Comparator(const void *context, const void *left, const void *right) {
46 return *(const int32_t *)left - *(const int32_t *)right;
49 U_CAPI int32_t U_EXPORT2
50 uprv_uint32Comparator(const void *context, const void *left, const void *right) {
51 uint32_t l=*(const uint32_t *)left, r=*(const uint32_t *)right;
53 /* compare directly because (l-r) would overflow the int32_t result */
63 /* Insertion sort using binary search --------------------------------------- */
65 U_CAPI int32_t U_EXPORT2
66 uprv_stableBinarySearch(char *array, int32_t limit, void *item, int32_t itemSize,
67 UComparator *cmp, const void *context) {
71 /* Binary search until we get down to a tiny sub-array. */
72 while((limit-start)>=MIN_QSORT) {
73 int32_t i=(start+limit)/2;
74 int32_t diff=cmp(context, item, array+i*itemSize);
77 * Found the item. We look for the *last* occurrence of such
78 * an item, for stable sorting.
79 * If we knew that there will be only few equal items,
80 * we could break now and enter the linear search.
81 * However, if there are many equal items, then it should be
82 * faster to continue with the binary search.
83 * It seems likely that we either have all unique items
84 * (where found will never become TRUE in the insertion sort)
85 * or potentially many duplicates.
96 /* Linear search over the remaining tiny sub-array. */
98 int32_t diff=cmp(context, item, array+start*itemSize);
106 return found ? (start-1) : ~start;
110 doInsertionSort(char *array, int32_t length, int32_t itemSize,
111 UComparator *cmp, const void *context, void *pv) {
114 for(j=1; j<length; ++j) {
115 char *item=array+j*itemSize;
116 int32_t insertionPoint=uprv_stableBinarySearch(array, j, item, itemSize, cmp, context);
117 if(insertionPoint<0) {
118 insertionPoint=~insertionPoint;
120 ++insertionPoint; /* one past the last equal item */
122 if(insertionPoint<j) {
123 char *dest=array+insertionPoint*itemSize;
124 uprv_memcpy(pv, item, itemSize); /* v=array[j] */
125 uprv_memmove(dest+itemSize, dest, (j-insertionPoint)*(size_t)itemSize);
126 uprv_memcpy(dest, pv, itemSize); /* array[insertionPoint]=v */
132 insertionSort(char *array, int32_t length, int32_t itemSize,
133 UComparator *cmp, const void *context, UErrorCode *pErrorCode) {
134 UAlignedMemory v[STACK_ITEM_SIZE/sizeof(UAlignedMemory)+1];
137 /* allocate an intermediate item variable (v) */
138 if(itemSize<=STACK_ITEM_SIZE) {
141 pv=uprv_malloc(itemSize);
143 *pErrorCode=U_MEMORY_ALLOCATION_ERROR;
148 doInsertionSort(array, length, itemSize, cmp, context, pv);
155 /* QuickSort ---------------------------------------------------------------- */
158 * This implementation is semi-recursive:
159 * It recurses for the smaller sub-array to shorten the recursion depth,
160 * and loops for the larger sub-array.
162 * Loosely after QuickSort algorithms in
164 * Algorithmen und Datenstrukturen mit Modula-2
165 * B.G. Teubner Stuttgart
170 subQuickSort(char *array, int32_t start, int32_t limit, int32_t itemSize,
171 UComparator *cmp, const void *context,
172 void *px, void *pw) {
175 /* start and left are inclusive, limit and right are exclusive */
177 if((start+MIN_QSORT)>=limit) {
178 doInsertionSort(array+start*itemSize, limit-start, itemSize, cmp, context, px);
185 /* x=array[middle] */
186 uprv_memcpy(px, array+(size_t)((start+limit)/2)*itemSize, itemSize);
189 while(/* array[left]<x */
190 cmp(context, array+left*itemSize, px)<0
194 while(/* x<array[right-1] */
195 cmp(context, px, array+(right-1)*itemSize)<0
200 /* swap array[left] and array[right-1] via w; ++left; --right */
205 uprv_memcpy(pw, array+(size_t)left*itemSize, itemSize);
206 uprv_memcpy(array+(size_t)left*itemSize, array+(size_t)right*itemSize, itemSize);
207 uprv_memcpy(array+(size_t)right*itemSize, pw, itemSize);
214 /* sort sub-arrays */
215 if((right-start)<(limit-left)) {
216 /* sort [start..right[ */
217 if(start<(right-1)) {
218 subQuickSort(array, start, right, itemSize, cmp, context, px, pw);
221 /* sort [left..limit[ */
224 /* sort [left..limit[ */
226 subQuickSort(array, left, limit, itemSize, cmp, context, px, pw);
229 /* sort [start..right[ */
232 } while(start<(limit-1));
236 quickSort(char *array, int32_t length, int32_t itemSize,
237 UComparator *cmp, const void *context, UErrorCode *pErrorCode) {
238 UAlignedMemory xw[(2*STACK_ITEM_SIZE)/sizeof(UAlignedMemory)+1];
241 /* allocate two intermediate item variables (x and w) */
242 if(itemSize<=STACK_ITEM_SIZE) {
245 p=uprv_malloc(2*itemSize);
247 *pErrorCode=U_MEMORY_ALLOCATION_ERROR;
252 subQuickSort(array, 0, length, itemSize,
253 cmp, context, p, (char *)p+itemSize);
260 /* uprv_sortArray() API ----------------------------------------------------- */
263 * Check arguments, select an appropriate implementation,
264 * cast the array to char * so that array+i*itemSize works.
266 U_CAPI void U_EXPORT2
267 uprv_sortArray(void *array, int32_t length, int32_t itemSize,
268 UComparator *cmp, const void *context,
269 UBool sortStable, UErrorCode *pErrorCode) {
270 if(pErrorCode==NULL || U_FAILURE(*pErrorCode)) {
273 if((length>0 && array==NULL) || length<0 || itemSize<=0 || cmp==NULL) {
274 *pErrorCode=U_ILLEGAL_ARGUMENT_ERROR;
280 } else if(length<MIN_QSORT || sortStable) {
281 insertionSort((char *)array, length, itemSize, cmp, context, pErrorCode);
283 quickSort((char *)array, length, itemSize, cmp, context, pErrorCode);