1 /*
2 * Copyright © 2017 Google, Inc.
3 *
4 * This is part of HarfBuzz, a text shaping library.
5 *
6 * Permission is hereby granted, without written agreement and without
7 * license or royalty fees, to use, copy, modify, and distribute this
8 * software and its documentation for any purpose, provided that the
9 * above copyright notice and the following two paragraphs appear in
10 * all copies of this software.
11 *
12 * IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE TO ANY PARTY FOR
13 * DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
14 * ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN
15 * IF THE COPYRIGHT HOLDER HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH
16 * DAMAGE.
17 *
18 * THE COPYRIGHT HOLDER SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING,
19 * BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
20 * FITNESS FOR A PARTICULAR PURPOSE. THE SOFTWARE PROVIDED HEREUNDER IS
21 * ON AN "AS IS" BASIS, AND THE COPYRIGHT HOLDER HAS NO OBLIGATION TO
22 * PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
23 *
24 * Google Author(s): Behdad Esfahbod
25 */
26
27 #ifndef HB_DSALGS_HH
28 #define HB_DSALGS_HH
29
30 #include "hb-private.hh"
31
32
33 static inline void *
34 hb_bsearch_r (const void *key, const void *base,
35 size_t nmemb, size_t size,
36 int (*compar)(const void *_key, const void *_item, void *_arg),
37 void *arg)
38 {
39 int min = 0, max = (int) nmemb - 1;
40 while (min <= max)
41 {
42 int mid = (min + max) / 2;
43 const void *p = (const void *) (((const char *) base) + (mid * size));
44 int c = compar (key, p, arg);
45 if (c < 0)
46 max = mid - 1;
47 else if (c > 0)
48 min = mid + 1;
49 else
50 return (void *) p;
51 }
52 return NULL;
53 }
54
55
56
57 /* From https://github.com/noporpoise/sort_r */
58
59 /* Isaac Turner 29 April 2014 Public Domain */
60
61 /*
62
63 hb_sort_r function to be exported.
64
65 Parameters:
66 base is the array to be sorted
67 nel is the number of elements in the array
68 width is the size in bytes of each element of the array
69 compar is the comparison function
70 arg is a pointer to be passed to the comparison function
71
72 void hb_sort_r(void *base, size_t nel, size_t width,
73 int (*compar)(const void *_a, const void *_b, void *_arg),
74 void *arg);
75 */
76
77
78 /* swap a, b iff a>b */
79 #ifndef __SUNPRO_CC
80 /* __restrict is same as restrict but better support on old machines */
81 static int sort_r_cmpswap(char *__restrict a, char *__restrict b, size_t w,
82 #else
83 static int sort_r_cmpswap(char *a, char *b, size_t w,
84 #endif
85 int (*compar)(const void *_a, const void *_b,
86 void *_arg),
87 void *arg)
88 {
89 char tmp, *end = a+w;
90 if(compar(a, b, arg) > 0) {
91 for(; a < end; a++, b++) { tmp = *a; *a = *b; *b = tmp; }
92 return 1;
93 }
94 return 0;
95 }
96
97 /* Note: quicksort is not stable, equivalent values may be swapped */
98 static inline void sort_r_simple(void *base, size_t nel, size_t w,
99 int (*compar)(const void *_a, const void *_b,
100 void *_arg),
101 void *arg)
102 {
103 char *b = (char *)base, *end = b + nel*w;
104 if(nel < 7) {
105 /* Insertion sort for arbitrarily small inputs */
106 char *pi, *pj;
107 for(pi = b+w; pi < end; pi += w) {
108 for(pj = pi; pj > b && sort_r_cmpswap(pj-w,pj,w,compar,arg); pj -= w) {}
109 }
110 }
111 else
112 {
113 /* nel > 6; Quicksort */
114
115 /* Use median of first, middle and last items as pivot */
116 char *x, *y, *xend, ch;
117 char *pl, *pr;
118 char *last = b+w*(nel-1), *tmp;
119 char *l[3];
120 l[0] = b;
121 l[1] = b+w*(nel/2);
122 l[2] = last;
123
124 if(compar(l[0],l[1],arg) > 0) { tmp=l[0]; l[0]=l[1]; l[1]=tmp; }
125 if(compar(l[1],l[2],arg) > 0) {
126 tmp=l[1]; l[1]=l[2]; l[2]=tmp; /* swap(l[1],l[2]) */
127 if(compar(l[0],l[1],arg) > 0) { tmp=l[0]; l[0]=l[1]; l[1]=tmp; }
128 }
129
130 /* swap l[id], l[2] to put pivot as last element */
131 for(x = l[1], y = last, xend = x+w; x<xend; x++, y++) {
132 ch = *x; *x = *y; *y = ch;
133 }
134
135 pl = b;
136 pr = last;
137
138 while(pl < pr) {
139 for(; pl < pr; pl += w) {
140 if(sort_r_cmpswap(pl, pr, w, compar, arg)) {
141 pr -= w; /* pivot now at pl */
142 break;
143 }
144 }
145 for(; pl < pr; pr -= w) {
146 if(sort_r_cmpswap(pl, pr, w, compar, arg)) {
147 pl += w; /* pivot now at pr */
148 break;
149 }
150 }
151 }
152
153 sort_r_simple(b, (pl-b)/w, w, compar, arg);
154 sort_r_simple(pl+w, (end-(pl+w))/w, w, compar, arg);
155 }
156 }
157
158 static inline void hb_sort_r(void *base, size_t nel, size_t width,
159 int (*compar)(const void *_a, const void *_b, void *_arg),
160 void *arg)
161 {
162 sort_r_simple(base, nel, width, compar, arg);
163 }
164
165 #endif /* HB_DSALGS_HH */