GDB (xrefs)

vec.c
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1 /* Vector API for GDB.
2 Copyright (C) 2004-2018 Free Software Foundation, Inc.
3 Contributed by Nathan Sidwell <nathan@codesourcery.com>
4
5 This file is part of GDB.
6
7 This program is free software; you can redistribute it and/or modify
8 it under the terms of the GNU General Public License as published by
9 the Free Software Foundation; either version 3 of the License, or
10 (at your option) any later version.
11
12 This program is distributed in the hope that it will be useful,
13 but WITHOUT ANY WARRANTY; without even the implied warranty of
14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 GNU General Public License for more details.
16
17 You should have received a copy of the GNU General Public License
18 along with this program. If not, see <http://www.gnu.org/licenses/>. */
19
20 #include "common-defs.h"
21 #include "vec.h"
22
23 struct vec_prefix
24 {
25 unsigned num;
26 unsigned alloc;
27 void *vec[1];
28 };
29
30 /* Calculate the new ALLOC value, making sure that abs(RESERVE) slots
31 are free. If RESERVE < 0 grow exactly, otherwise grow
32 exponentially. */
33
34 static inline unsigned
35 calculate_allocation (const struct vec_prefix *pfx, int reserve)
36 {
37 unsigned alloc = 0;
38 unsigned num = 0;
39
40 if (pfx)
41 {
42 alloc = pfx->alloc;
43 num = pfx->num;
44 }
45 else if (!reserve)
46 /* If there's no prefix, and we've not requested anything, then we
47 will create a NULL vector. */
48 return 0;
49
50 /* We must have run out of room. */
51 gdb_assert (alloc - num < (unsigned)(reserve < 0 ? -reserve : reserve));
52
53 if (reserve < 0)
54 /* Exact size. */
55 alloc = num + -reserve;
56 else
57 {
58 /* Exponential growth. */
59 if (!alloc)
60 alloc = 4;
61 else if (alloc < 16)
62 /* Double when small. */
63 alloc = alloc * 2;
64 else
65 /* Grow slower when large. */
66 alloc = (alloc * 3 / 2);
67
68 /* If this is still too small, set it to the right size. */
69 if (alloc < num + reserve)
70 alloc = num + reserve;
71 }
72 return alloc;
73 }
74
75 /* Ensure there are at least abs(RESERVE) free slots in VEC. If
76 RESERVE < 0 grow exactly, else grow exponentially. As a special
77 case, if VEC is NULL, and RESERVE is 0, no vector will be created. */
78
79 void *
80 vec_p_reserve (void *vec, int reserve)
81 {
82 return vec_o_reserve (vec, reserve,
83 offsetof (struct vec_prefix, vec), sizeof (void *));
84 }
85
86 /* As vec_p_reserve, but for object vectors. The vector's trailing
87 array is at VEC_OFFSET offset and consists of ELT_SIZE sized
88 elements. */
89
90 void *
91 vec_o_reserve (void *vec, int reserve, size_t vec_offset, size_t elt_size)
92 {
93 struct vec_prefix *pfx = (struct vec_prefix *) vec;
94 unsigned alloc = calculate_allocation (pfx, reserve);
95
96 if (!alloc)
97 return NULL;
98
99 vec = xrealloc (vec, vec_offset + alloc * elt_size);
100 ((struct vec_prefix *)vec)->alloc = alloc;
101 if (!pfx)
102 ((struct vec_prefix *)vec)->num = 0;
103
104 return vec;
105 }
106
107 #if 0
108 /* Example uses. */
109 DEF_VEC_I (int);
110 typedef struct X
111 {
112 int i;
113 } obj_t;
114 typedef obj_t *ptr_t;
115
116 DEF_VEC_P (ptr_t);
117 DEF_VEC_O (obj_t);
118 #endif
vec_offset
#define vec_offset(T, VPTR)
Definition: vec.h:471
vec_prefix::alloc
unsigned alloc
Definition: vec.c:26
DEF_VEC_O
#define DEF_VEC_O(T)
Definition: vec.h:456
DEF_VEC_P
#define DEF_VEC_P(T)
Definition: vec.h:441
vec_o_reserve
void * vec_o_reserve(void *vec, int reserve, size_t vec_offset, size_t elt_size)
Definition: vec.c:91
common-defs.h
X
Definition: ia64-tdep.c:85
gdb_assert
#define gdb_assert(expr)
Definition: gdb_assert.h:32
vec_prefix::num
unsigned num
Definition: vec.c:25
xrealloc
PTR xrealloc(PTR ptr, size_t size)
Definition: common-utils.c:52
vec_p_reserve
void * vec_p_reserve(void *vec, int reserve)
Definition: vec.c:80
vec_prefix::vec
void * vec[1]
Definition: vec.c:27
DEF_VEC_I
DEF_VEC_I(offset_type)
calculate_allocation
static unsigned calculate_allocation(const struct vec_prefix *pfx, int reserve)
Definition: vec.c:35
vec_prefix
Definition: vec.c:23
vec.h