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/* Vector API for GDB.
Copyright (C) 2004-2012 Free Software Foundation, Inc.
Contributed by Nathan Sidwell <nathan@codesourcery.com>
This file is part of GDB.
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>. */
#include "defs.h"
#include "vec.h"
struct vec_prefix
{
unsigned num;
unsigned alloc;
void *vec[1];
};
/* Calculate the new ALLOC value, making sure that abs(RESERVE) slots
are free. If RESERVE < 0 grow exactly, otherwise grow
exponentially. */
static inline unsigned
calculate_allocation (const struct vec_prefix *pfx, int reserve)
{
unsigned alloc = 0;
unsigned num = 0;
if (pfx)
{
alloc = pfx->alloc;
num = pfx->num;
}
else if (!reserve)
/* If there's no prefix, and we've not requested anything, then we
will create a NULL vector. */
return 0;
/* We must have run out of room. */
gdb_assert (alloc - num < (unsigned)(reserve < 0 ? -reserve : reserve));
if (reserve < 0)
/* Exact size. */
alloc = num + -reserve;
else
{
/* Exponential growth. */
if (!alloc)
alloc = 4;
else if (alloc < 16)
/* Double when small. */
alloc = alloc * 2;
else
/* Grow slower when large. */
alloc = (alloc * 3 / 2);
/* If this is still too small, set it to the right size. */
if (alloc < num + reserve)
alloc = num + reserve;
}
return alloc;
}
/* Ensure there are at least abs(RESERVE) free slots in VEC. If
RESERVE < 0 grow exactly, else grow exponentially. As a special
case, if VEC is NULL, and RESERVE is 0, no vector will be created. */
void *
vec_p_reserve (void *vec, int reserve)
{
return vec_o_reserve (vec, reserve,
offsetof (struct vec_prefix, vec), sizeof (void *));
}
/* As vec_p_reserve, but for object vectors. The vector's trailing
array is at VEC_OFFSET offset and consists of ELT_SIZE sized
elements. */
void *
vec_o_reserve (void *vec, int reserve, size_t vec_offset, size_t elt_size)
{
struct vec_prefix *pfx = vec;
unsigned alloc = calculate_allocation (pfx, reserve);
if (!alloc)
return NULL;
vec = xrealloc (vec, vec_offset + alloc * elt_size);
((struct vec_prefix *)vec)->alloc = alloc;
if (!pfx)
((struct vec_prefix *)vec)->num = 0;
return vec;
}
#if 0
/* Example uses. */
DEF_VEC_I (int);
typedef struct X
{
int i;
} obj_t;
typedef obj_t *ptr_t;
DEF_VEC_P (ptr_t);
DEF_VEC_O (obj_t);
#endif
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