gdb/common/vec.c - gdb

Data types defined

Functions defined

Source code

  1. /* Vector API for GDB.
  2.    Copyright (C) 2004-2015 Free Software Foundation, Inc.
  3.    Contributed by Nathan Sidwell <nathan@codesourcery.com>

  5.    This file is part of GDB.

  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.

  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.

  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/>.  */

  20. #include "common-defs.h"
  21. #include "vec.h"

  23. ‌struct vec_prefix
  24. {
  25.   unsigned num;
  26.   unsigned alloc;
  27.   void *vec[1];
  28. };

  30. /* Calculate the new ALLOC value, making sure that abs(RESERVE) slots
  31.    are free.  If RESERVE < 0 grow exactly, otherwise grow
  32.    exponentially.  */

  34. static inline unsigned
  35. ‌calculate_allocation (const struct vec_prefix *pfx, int reserve)
  36. {
  37.   unsigned alloc = 0;
  38.   unsigned num = 0;

  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;

  50.   /* We must have run out of room.  */
  51.   gdb_assert (alloc - num < (unsigned)(reserve < 0 ? -reserve : reserve));

  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);

  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. }

  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.  */

  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. }

  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.  */

  90. void *
  91. ‌vec_o_reserve (void *vec, int reserve, size_t vec_offset, size_t elt_size)
  92. {
  93.   struct vec_prefix *pfx = vec;
  94.   unsigned alloc = calculate_allocation (pfx, reserve);

  96.   if (!alloc)
  97.     return NULL;

  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;

  104.   return vec;
  105. }

  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;

  116. DEF_VEC_P (ptr_t);
  117. DEF_VEC_O (obj_t);
  118. #endif