Check in the pristine copy of ICU 4.6...

icu46/source/common/uarrsort.c

+/*
+*******************************************************************************
+*
+*   Copyright (C) 2003, 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 {
+    MIN_QSORT=9, /* from Knuth */
+    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;
+    }
+}
+
+/* Straight insertion sort from Knuth vol. III, pg. 81 ---------------------- */
+
+static void
+doInsertionSort(char *array, int32_t start, int32_t limit, int32_t itemSize,
+                UComparator *cmp, const void *context, void *pv) {
+    int32_t i, j;
+
+    for(j=start+1; j<limit; ++j) {
+        /* v=array[j] */
+        uprv_memcpy(pv, array+j*itemSize, itemSize);
+
+        for(i=j; i>start; --i) {
+            if(/* v>=array[i-1] */ cmp(context, pv, array+(i-1)*itemSize)>=0) {
+                break;
+            }
+
+            /* array[i]=array[i-1]; */
+            uprv_memcpy(array+i*itemSize, array+(i-1)*itemSize, itemSize);
+        }
+
+        if(i!=j) {
+            /* array[i]=v; */
+            uprv_memcpy(array+i*itemSize, pv, itemSize);
+        }
+    }
+}
+
+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, 0, 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, limit, 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);
+        /* could add heapSort or similar for stable sorting of longer arrays */
+    } else {
+        quickSort((char *)array, length, itemSize, cmp, context, pErrorCode);
+    }
+}