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119 lines
3.0 KiB
C
119 lines
3.0 KiB
C
/* Vector API for GDB.
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Copyright (C) 2004-2018 Free Software Foundation, Inc.
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Contributed by Nathan Sidwell <nathan@codesourcery.com>
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This file is part of GDB.
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>. */
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#include "common-defs.h"
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#include "vec.h"
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struct vec_prefix
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{
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unsigned num;
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unsigned alloc;
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void *vec[1];
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};
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/* Calculate the new ALLOC value, making sure that abs(RESERVE) slots
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are free. If RESERVE < 0 grow exactly, otherwise grow
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exponentially. */
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static inline unsigned
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calculate_allocation (const struct vec_prefix *pfx, int reserve)
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{
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unsigned alloc = 0;
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unsigned num = 0;
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if (pfx)
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{
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alloc = pfx->alloc;
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num = pfx->num;
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}
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else if (!reserve)
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/* If there's no prefix, and we've not requested anything, then we
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will create a NULL vector. */
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return 0;
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/* We must have run out of room. */
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gdb_assert (alloc - num < (unsigned)(reserve < 0 ? -reserve : reserve));
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if (reserve < 0)
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/* Exact size. */
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alloc = num + -reserve;
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else
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{
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/* Exponential growth. */
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if (!alloc)
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alloc = 4;
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else if (alloc < 16)
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/* Double when small. */
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alloc = alloc * 2;
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else
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/* Grow slower when large. */
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alloc = (alloc * 3 / 2);
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/* If this is still too small, set it to the right size. */
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if (alloc < num + reserve)
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alloc = num + reserve;
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}
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return alloc;
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}
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/* Ensure there are at least abs(RESERVE) free slots in VEC. If
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RESERVE < 0 grow exactly, else grow exponentially. As a special
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case, if VEC is NULL, and RESERVE is 0, no vector will be created. */
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void *
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vec_p_reserve (void *vec, int reserve)
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{
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return vec_o_reserve (vec, reserve,
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offsetof (struct vec_prefix, vec), sizeof (void *));
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}
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/* As vec_p_reserve, but for object vectors. The vector's trailing
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array is at VEC_OFFSET offset and consists of ELT_SIZE sized
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elements. */
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void *
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vec_o_reserve (void *vec, int reserve, size_t vec_offset, size_t elt_size)
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{
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struct vec_prefix *pfx = (struct vec_prefix *) vec;
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unsigned alloc = calculate_allocation (pfx, reserve);
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if (!alloc)
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return NULL;
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vec = xrealloc (vec, vec_offset + alloc * elt_size);
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((struct vec_prefix *)vec)->alloc = alloc;
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if (!pfx)
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((struct vec_prefix *)vec)->num = 0;
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return vec;
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}
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#if 0
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/* Example uses. */
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DEF_VEC_I (int);
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typedef struct X
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{
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int i;
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} obj_t;
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typedef obj_t *ptr_t;
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DEF_VEC_P (ptr_t);
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DEF_VEC_O (obj_t);
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#endif
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