basic: add a Bitmap implementation
For when a Hashmap is overkill.
This commit is contained in:
Tom Gundersen
@@ -791,6 +791,8 @@ libbasic_la_SOURCES = \
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src/basic/siphash24.h \
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src/basic/set.h \
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src/basic/ordered-set.h \
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src/basic/bitmap.c \
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src/basic/bitmap.h \
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src/basic/fdset.c \
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src/basic/fdset.h \
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src/basic/prioq.c \
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@@ -1412,6 +1414,7 @@ tests += \
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test-time \
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test-hashmap \
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test-set \
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test-bitmap \
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test-list \
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test-unaligned \
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test-tables \
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@@ -1768,6 +1771,12 @@ test_set_SOURCES = \
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test_set_LDADD = \
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libshared.la
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test_bitmap_SOURCES = \
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src/test/test-bitmap.c
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test_bitmap_LDADD = \
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libshared.la
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test_xml_SOURCES = \
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src/test/test-xml.c
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@@ -0,0 +1,208 @@
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/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
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/***
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This file is part of systemd.
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Copyright 2015 Tom Gundersen
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systemd is free software; you can redistribute it and/or modify it
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under the terms of the GNU Lesser General Public License as published by
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the Free Software Foundation; either version 2.1 of the License, or
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(at your option) any later version.
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systemd is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public License
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along with systemd; If not, see <http://www.gnu.org/licenses/>.
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***/
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#include "util.h"
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#include "bitmap.h"
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struct Bitmap {
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long long unsigned *bitmaps;
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size_t n_bitmaps;
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size_t bitmaps_allocated;
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unsigned next_entry;
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};
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/* Bitmaps are only meant to store relatively small numbers
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* (corresponding to, say, an enum), so it is ok to limit
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* the max entry. 64k should be plenty. */
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#define BITMAPS_MAX_ENTRY 0xffff
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/* This indicates that we reached the end of the bitmap */
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#define BITMAP_END ((unsigned) -1)
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#define BITMAP_NUM_TO_OFFSET(n) ((n) / (sizeof(long long unsigned) * 8))
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#define BITMAP_NUM_TO_REM(n) ((n) % (sizeof(long long unsigned) * 8))
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#define BITMAP_OFFSET_TO_NUM(offset, rem) ((offset) * sizeof(long long unsigned) * 8 + (rem))
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Bitmap *bitmap_new(void) {
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return new0(Bitmap, 1);
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}
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void bitmap_free(Bitmap *b) {
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if (!b)
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return;
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free(b->bitmaps);
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free(b);
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}
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int bitmap_ensure_allocated(Bitmap **b) {
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Bitmap *a;
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if (*b)
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return 0;
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a = bitmap_new();
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if (!a)
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return -ENOMEM;
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*b = a;
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return 0;
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}
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int bitmap_set(Bitmap *b, unsigned n) {
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long long bitmask;
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unsigned offset;
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assert(b);
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/* we refuse to allocate huge bitmaps */
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if (n > BITMAPS_MAX_ENTRY)
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return -ERANGE;
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offset = BITMAP_NUM_TO_OFFSET(n);
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if (offset >= b->n_bitmaps) {
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if (!GREEDY_REALLOC0(b->bitmaps, b->bitmaps_allocated, offset + 1))
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return -ENOMEM;
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b->n_bitmaps = offset + 1;
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}
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bitmask = 1 << BITMAP_NUM_TO_REM(n);
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b->bitmaps[offset] |= bitmask;
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return 0;
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}
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void bitmap_unset(Bitmap *b, unsigned n) {
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long long bitmask;
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unsigned offset;
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assert(b);
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offset = BITMAP_NUM_TO_OFFSET(n);
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if (offset >= b->n_bitmaps)
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return;
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bitmask = 1 << BITMAP_NUM_TO_REM(n);
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b->bitmaps[offset] &= ~bitmask;
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}
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bool bitmap_isset(Bitmap *b, unsigned n) {
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long long bitmask;
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unsigned offset;
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if (!b || !b->bitmaps)
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return false;
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offset = BITMAP_NUM_TO_OFFSET(n);
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if (offset >= b->n_bitmaps)
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return false;
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bitmask = 1 << BITMAP_NUM_TO_REM(n);
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return !!(b->bitmaps[offset] & bitmask);
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}
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bool bitmap_isclear(Bitmap *b) {
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unsigned i;
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assert(b);
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for (i = 0; i < b->n_bitmaps; i++)
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if (b->bitmaps[i])
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return false;
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return true;
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}
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void bitmap_clear(Bitmap *b) {
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unsigned i;
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assert(b);
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for (i = 0; i < b->n_bitmaps; i++)
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b->bitmaps[i] = 0;
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}
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void bitmap_rewind(Bitmap *b) {
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if (!b)
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return;
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b->next_entry = 0;
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}
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bool bitmap_next(Bitmap *b, unsigned *n) {
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long long bitmask;
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unsigned offset, rem;
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if (!b && b->next_entry == BITMAP_END)
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return false;
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offset = BITMAP_NUM_TO_OFFSET(b->next_entry);
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rem = BITMAP_NUM_TO_REM(b->next_entry);
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bitmask = 1 << rem;
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for (; offset < b->n_bitmaps; offset ++) {
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if (b->bitmaps[offset]) {
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for (; bitmask; bitmask <<= 1, rem ++) {
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if (b->bitmaps[offset] & bitmask) {
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*n = BITMAP_OFFSET_TO_NUM(offset, rem);
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b->next_entry = *n + 1;
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return true;
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}
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}
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}
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rem = 0;
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bitmask = 1;
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}
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b->next_entry = BITMAP_END;
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return false;
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}
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bool bitmap_equal(Bitmap *a, Bitmap *b) {
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unsigned i;
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if (!a ^ !b)
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return false;
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if (!a)
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return true;
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if (a->n_bitmaps != b->n_bitmaps)
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return false;
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for (i = 0; i < a->n_bitmaps; i++)
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if (a->bitmaps[i] != b->bitmaps[i])
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return false;
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return true;
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}
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@@ -0,0 +1,50 @@
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/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
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#pragma once
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/***
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This file is part of systemd.
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Copyright 2015 Tom Gundersen
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systemd is free software; you can redistribute it and/or modify it
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under the terms of the GNU Lesser General Public License as published by
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the Free Software Foundation; either version 2.1 of the License, or
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(at your option) any later version.
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systemd is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public License
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along with systemd; If not, see <http://www.gnu.org/licenses/>.
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***/
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#include "macro.h"
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typedef struct Bitmap Bitmap;
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Bitmap *bitmap_new(void);
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void bitmap_free(Bitmap *b);
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int bitmap_ensure_allocated(Bitmap **b);
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int bitmap_set(Bitmap *b, unsigned n);
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void bitmap_unset(Bitmap *b, unsigned n);
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bool bitmap_isset(Bitmap *b, unsigned n);
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bool bitmap_isclear(Bitmap *b);
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void bitmap_clear(Bitmap *b);
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void bitmap_rewind(Bitmap *b);
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bool bitmap_next(Bitmap *b, unsigned *n);
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bool bitmap_equal(Bitmap *a, Bitmap *b);
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#define BITMAP_FOREACH(n, b) \
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for (bitmap_rewind(b); bitmap_next((b), &(n)); )
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DEFINE_TRIVIAL_CLEANUP_FUNC(Bitmap*, bitmap_free);
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#define _cleanup_bitmap_free_ _cleanup_(bitmap_freep)
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@@ -0,0 +1,96 @@
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/***
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This file is part of systemd
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Copyright 2015 Tom Gundersen
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systemd is free software; you can redistribute it and/or modify it
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under the terms of the GNU Lesser General Public License as published by
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the Free Software Foundation; either version 2.1 of the License, or
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(at your option) any later version.
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systemd is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public License
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along with systemd; If not, see <http://www.gnu.org/licenses/>.
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***/
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#include "bitmap.h"
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int main(int argc, const char *argv[]) {
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_cleanup_bitmap_free_ Bitmap *b = NULL;
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unsigned n = (unsigned) -1, i = 0;
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b = bitmap_new();
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assert_se(b);
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assert_se(bitmap_ensure_allocated(&b) == 0);
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bitmap_free(b);
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b = NULL;
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assert_se(bitmap_ensure_allocated(&b) == 0);
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assert_se(bitmap_isset(b, 0) == false);
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assert_se(bitmap_isset(b, 1) == false);
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assert_se(bitmap_isset(b, 256) == false);
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assert_se(bitmap_isclear(b) == true);
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assert_se(bitmap_set(b, 0) == 0);
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assert_se(bitmap_isset(b, 0) == true);
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assert_se(bitmap_isclear(b) == false);
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bitmap_unset(b, 0);
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assert_se(bitmap_isset(b, 0) == false);
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assert_se(bitmap_isclear(b) == true);
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assert_se(bitmap_set(b, 1) == 0);
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assert_se(bitmap_isset(b, 1) == true);
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assert_se(bitmap_isclear(b) == false);
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bitmap_unset(b, 1);
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assert_se(bitmap_isset(b, 1) == false);
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assert_se(bitmap_isclear(b) == true);
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assert_se(bitmap_set(b, 256) == 0);
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assert_se(bitmap_isset(b, 256) == true);
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assert_se(bitmap_isclear(b) == false);
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bitmap_unset(b, 256);
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assert_se(bitmap_isset(b, 256) == false);
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assert_se(bitmap_isclear(b) == true);
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assert_se(bitmap_set(b, 0) == 0);
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assert_se(bitmap_set(b, 1) == 0);
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assert_se(bitmap_set(b, 256) == 0);
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BITMAP_FOREACH(n, b) {
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assert_se(n == i);
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if (i == 0)
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i = 1;
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else if (i == 1)
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i = 256;
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else if (i == 256)
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i = (unsigned) -1;
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}
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assert_se(i == (unsigned) -1);
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i = 0;
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BITMAP_FOREACH(n, b) {
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assert_se(n == i);
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if (i == 0)
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i = 1;
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else if (i == 1)
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i = 256;
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else if (i == 256)
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i = (unsigned) -1;
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}
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assert_se(i == (unsigned) -1);
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bitmap_clear(b);
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assert_se(bitmap_isclear(b) == true);
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assert_se(bitmap_set(b, (unsigned) -1) == -ERANGE);
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return 0;
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}
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