| 1 | /* Vector API for GDB. |
| 2 | Copyright (C) 2004, 2005, 2006, 2007, 2008 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 "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 = 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 |