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Diffstat (limited to 'src/libbasic/bitmap.c')
| -rw-r--r-- | src/libbasic/bitmap.c | 220 |
1 files changed, 220 insertions, 0 deletions
diff --git a/src/libbasic/bitmap.c b/src/libbasic/bitmap.c new file mode 100644 index 0000000000..ad1fda0198 --- /dev/null +++ b/src/libbasic/bitmap.c @@ -0,0 +1,220 @@ +/*** + This file is part of systemd. + + Copyright 2015 Tom Gundersen + + systemd is free software; you can redistribute it and/or modify it + under the terms of the GNU Lesser General Public License as published by + the Free Software Foundation; either version 2.1 of the License, or + (at your option) any later version. + + systemd 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 + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public License + along with systemd; If not, see <http://www.gnu.org/licenses/>. +***/ + +#include <errno.h> +#include <stddef.h> +#include <stdint.h> +#include <stdlib.h> +#include <string.h> + +#include "alloc-util.h" +#include "bitmap.h" +#include "hashmap.h" +#include "macro.h" + +struct Bitmap { + uint64_t *bitmaps; + size_t n_bitmaps; + size_t bitmaps_allocated; +}; + +/* Bitmaps are only meant to store relatively small numbers + * (corresponding to, say, an enum), so it is ok to limit + * the max entry. 64k should be plenty. */ +#define BITMAPS_MAX_ENTRY 0xffff + +/* This indicates that we reached the end of the bitmap */ +#define BITMAP_END ((unsigned) -1) + +#define BITMAP_NUM_TO_OFFSET(n) ((n) / (sizeof(uint64_t) * 8)) +#define BITMAP_NUM_TO_REM(n) ((n) % (sizeof(uint64_t) * 8)) +#define BITMAP_OFFSET_TO_NUM(offset, rem) ((offset) * sizeof(uint64_t) * 8 + (rem)) + +Bitmap *bitmap_new(void) { + return new0(Bitmap, 1); +} + +void bitmap_free(Bitmap *b) { + if (!b) + return; + + free(b->bitmaps); + free(b); +} + +int bitmap_ensure_allocated(Bitmap **b) { + Bitmap *a; + + assert(b); + + if (*b) + return 0; + + a = bitmap_new(); + if (!a) + return -ENOMEM; + + *b = a; + + return 0; +} + +int bitmap_set(Bitmap *b, unsigned n) { + uint64_t bitmask; + unsigned offset; + + assert(b); + + /* we refuse to allocate huge bitmaps */ + if (n > BITMAPS_MAX_ENTRY) + return -ERANGE; + + offset = BITMAP_NUM_TO_OFFSET(n); + + if (offset >= b->n_bitmaps) { + if (!GREEDY_REALLOC0(b->bitmaps, b->bitmaps_allocated, offset + 1)) + return -ENOMEM; + + b->n_bitmaps = offset + 1; + } + + bitmask = UINT64_C(1) << BITMAP_NUM_TO_REM(n); + + b->bitmaps[offset] |= bitmask; + + return 0; +} + +void bitmap_unset(Bitmap *b, unsigned n) { + uint64_t bitmask; + unsigned offset; + + if (!b) + return; + + offset = BITMAP_NUM_TO_OFFSET(n); + + if (offset >= b->n_bitmaps) + return; + + bitmask = UINT64_C(1) << BITMAP_NUM_TO_REM(n); + + b->bitmaps[offset] &= ~bitmask; +} + +bool bitmap_isset(Bitmap *b, unsigned n) { + uint64_t bitmask; + unsigned offset; + + if (!b) + return false; + + offset = BITMAP_NUM_TO_OFFSET(n); + + if (offset >= b->n_bitmaps) + return false; + + bitmask = UINT64_C(1) << BITMAP_NUM_TO_REM(n); + + return !!(b->bitmaps[offset] & bitmask); +} + +bool bitmap_isclear(Bitmap *b) { + unsigned i; + + if (!b) + return true; + + for (i = 0; i < b->n_bitmaps; i++) + if (b->bitmaps[i] != 0) + return false; + + return true; +} + +void bitmap_clear(Bitmap *b) { + + if (!b) + return; + + b->bitmaps = mfree(b->bitmaps); + b->n_bitmaps = 0; + b->bitmaps_allocated = 0; +} + +bool bitmap_iterate(Bitmap *b, Iterator *i, unsigned *n) { + uint64_t bitmask; + unsigned offset, rem; + + assert(i); + assert(n); + + if (!b || i->idx == BITMAP_END) + return false; + + offset = BITMAP_NUM_TO_OFFSET(i->idx); + rem = BITMAP_NUM_TO_REM(i->idx); + bitmask = UINT64_C(1) << rem; + + for (; offset < b->n_bitmaps; offset ++) { + if (b->bitmaps[offset]) { + for (; bitmask; bitmask <<= 1, rem ++) { + if (b->bitmaps[offset] & bitmask) { + *n = BITMAP_OFFSET_TO_NUM(offset, rem); + i->idx = *n + 1; + + return true; + } + } + } + + rem = 0; + bitmask = 1; + } + + i->idx = BITMAP_END; + + return false; +} + +bool bitmap_equal(Bitmap *a, Bitmap *b) { + size_t common_n_bitmaps; + Bitmap *c; + unsigned i; + + if (a == b) + return true; + + if (!a != !b) + return false; + + if (!a) + return true; + + common_n_bitmaps = MIN(a->n_bitmaps, b->n_bitmaps); + if (memcmp(a->bitmaps, b->bitmaps, sizeof(uint64_t) * common_n_bitmaps) != 0) + return false; + + c = a->n_bitmaps > b->n_bitmaps ? a : b; + for (i = common_n_bitmaps; i < c->n_bitmaps; i++) + if (c->bitmaps[i] != 0) + return false; + + return true; +} |