162 lines
4.4 KiB
C++
162 lines
4.4 KiB
C++
/*
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* Copyright © 2017 Google, Inc.
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*
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* This is part of HarfBuzz, a text shaping library.
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*
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* Permission is hereby granted, without written agreement and without
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* license or royalty fees, to use, copy, modify, and distribute this
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* software and its documentation for any purpose, provided that the
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* above copyright notice and the following two paragraphs appear in
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* all copies of this software.
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*
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* IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE TO ANY PARTY FOR
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* DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
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* ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN
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* IF THE COPYRIGHT HOLDER HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH
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* DAMAGE.
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*
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* THE COPYRIGHT HOLDER SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING,
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* BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
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* FITNESS FOR A PARTICULAR PURPOSE. THE SOFTWARE PROVIDED HEREUNDER IS
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* ON AN "AS IS" BASIS, AND THE COPYRIGHT HOLDER HAS NO OBLIGATION TO
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* PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
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*
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* Google Author(s): Behdad Esfahbod
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*/
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#ifndef HB_DSALGS_HH
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#define HB_DSALGS_HH
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#include "hb-private.hh"
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static inline void *
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hb_bsearch_r (const void *key, const void *base,
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size_t nmemb, size_t size,
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int (*compar)(const void *_key, const void *_item, void *_arg),
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void *arg)
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{
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int min = 0, max = (int) nmemb - 1;
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while (min <= max)
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{
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int mid = (min + max) / 2;
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const void *p = (const void *) (((const char *) base) + (mid * size));
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int c = compar (key, p, arg);
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if (c < 0)
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max = mid - 1;
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else if (c > 0)
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min = mid + 1;
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else
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return (void *) p;
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}
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return NULL;
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}
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/* From https://github.com/noporpoise/sort_r */
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/* Isaac Turner 29 April 2014 Public Domain */
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/*
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hb_sort_r function to be exported.
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Parameters:
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base is the array to be sorted
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nel is the number of elements in the array
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width is the size in bytes of each element of the array
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compar is the comparison function
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arg is a pointer to be passed to the comparison function
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void hb_sort_r(void *base, size_t nel, size_t width,
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int (*compar)(const void *_a, const void *_b, void *_arg),
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void *arg);
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*/
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/* swap a, b iff a>b */
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/* __restrict is same as restrict but better support on old machines */
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static int sort_r_cmpswap(char *__restrict a, char *__restrict b, size_t w,
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int (*compar)(const void *_a, const void *_b,
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void *_arg),
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void *arg)
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{
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char tmp, *end = a+w;
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if(compar(a, b, arg) > 0) {
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for(; a < end; a++, b++) { tmp = *a; *a = *b; *b = tmp; }
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return 1;
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}
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return 0;
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}
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/* Note: quicksort is not stable, equivalent values may be swapped */
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static inline void sort_r_simple(void *base, size_t nel, size_t w,
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int (*compar)(const void *_a, const void *_b,
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void *_arg),
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void *arg)
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{
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char *b = (char *)base, *end = b + nel*w;
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if(nel < 7) {
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/* Insertion sort for arbitrarily small inputs */
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char *pi, *pj;
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for(pi = b+w; pi < end; pi += w) {
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for(pj = pi; pj > b && sort_r_cmpswap(pj-w,pj,w,compar,arg); pj -= w) {}
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}
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}
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else
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{
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/* nel > 6; Quicksort */
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/* Use median of first, middle and last items as pivot */
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char *x, *y, *xend, ch;
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char *pl, *pr;
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char *last = b+w*(nel-1), *tmp;
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char *l[3];
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l[0] = b;
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l[1] = b+w*(nel/2);
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l[2] = last;
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if(compar(l[0],l[1],arg) > 0) { tmp=l[0]; l[0]=l[1]; l[1]=tmp; }
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if(compar(l[1],l[2],arg) > 0) {
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tmp=l[1]; l[1]=l[2]; l[2]=tmp; /* swap(l[1],l[2]) */
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if(compar(l[0],l[1],arg) > 0) { tmp=l[0]; l[0]=l[1]; l[1]=tmp; }
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}
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/* swap l[id], l[2] to put pivot as last element */
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for(x = l[1], y = last, xend = x+w; x<xend; x++, y++) {
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ch = *x; *x = *y; *y = ch;
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}
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pl = b;
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pr = last;
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while(pl < pr) {
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for(; pl < pr; pl += w) {
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if(sort_r_cmpswap(pl, pr, w, compar, arg)) {
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pr -= w; /* pivot now at pl */
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break;
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}
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}
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for(; pl < pr; pr -= w) {
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if(sort_r_cmpswap(pl, pr, w, compar, arg)) {
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pl += w; /* pivot now at pr */
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break;
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}
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}
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}
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sort_r_simple(b, (pl-b)/w, w, compar, arg);
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sort_r_simple(pl+w, (end-(pl+w))/w, w, compar, arg);
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}
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}
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static inline void hb_sort_r(void *base, size_t nel, size_t width,
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int (*compar)(const void *_a, const void *_b, void *_arg),
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void *arg)
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{
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sort_r_simple(base, nel, width, compar, arg);
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}
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#endif /* HB_DSALGS_HH */
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