Tor 0.4.9.0-alpha-dev
bitarray.h
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1/* Copyright (c) 2003-2004, Roger Dingledine
2 * Copyright (c) 2004-2006, Roger Dingledine, Nick Mathewson.
3 * Copyright (c) 2007-2021, The Tor Project, Inc. */
4/* See LICENSE for licensing information */
5
6#ifndef TOR_BITARRAY_H
7#define TOR_BITARRAY_H
8
9/**
10 * \file bitarray.h
11 *
12 * \brief Implements a variable-sized (but non-resizeable) bit-array.
13 **/
14
15#include "orconfig.h"
16#include <string.h>
17#include "lib/cc/torint.h"
18#include "lib/malloc/malloc.h"
19
20#if SIZEOF_INT == 4
21#define BITARRAY_SHIFT 5
22#elif SIZEOF_INT == 8
23#define BITARRAY_SHIFT 6
24#else
25#error "int is neither 4 nor 8 bytes. I can't deal with that."
26#endif /* SIZEOF_INT == 4 || ... */
27#define BITARRAY_MASK ((1u<<BITARRAY_SHIFT)-1)
28
29/** A random-access array of one-bit-wide elements. */
30typedef unsigned int bitarray_t;
31/** Create a new bit array that can hold <b>n_bits</b> bits. */
32static inline bitarray_t *
33bitarray_init_zero(unsigned int n_bits)
34{
35 /* round up to the next int. */
36 size_t sz = (n_bits+BITARRAY_MASK) >> BITARRAY_SHIFT;
37 return tor_calloc(sz, sizeof(unsigned int));
38}
39/** Expand <b>ba</b> from holding <b>n_bits_old</b> to <b>n_bits_new</b>,
40 * clearing all new bits. Returns a possibly changed pointer to the
41 * bitarray. */
42static inline bitarray_t *
44 unsigned int n_bits_old, unsigned int n_bits_new)
45{
46 size_t sz_old = (n_bits_old+BITARRAY_MASK) >> BITARRAY_SHIFT;
47 size_t sz_new = (n_bits_new+BITARRAY_MASK) >> BITARRAY_SHIFT;
48 char *ptr;
49 if (sz_new <= sz_old)
50 return ba;
51 ptr = tor_reallocarray(ba, sz_new, sizeof(unsigned int));
52 /* This memset does nothing to the older excess bytes. But they were
53 * already set to 0 by bitarry_init_zero. */
54 memset(ptr+sz_old*sizeof(unsigned int), 0,
55 (sz_new-sz_old)*sizeof(unsigned int));
56 return (bitarray_t*) ptr;
57}
58/** Free the bit array <b>ba</b>. */
59static inline void
61{
62 tor_free(ba);
63}
64#define bitarray_free(ba) FREE_AND_NULL(bitarray_t, bitarray_free_, (ba))
65
66/** Set the <b>bit</b>th bit in <b>b</b> to 1. */
67static inline void
69{
70 b[bit >> BITARRAY_SHIFT] |= (1u << (bit & BITARRAY_MASK));
71}
72/** Set the <b>bit</b>th bit in <b>b</b> to 0. */
73static inline void
75{
76 b[bit >> BITARRAY_SHIFT] &= ~ (1u << (bit & BITARRAY_MASK));
77}
78/** Return true iff <b>bit</b>th bit in <b>b</b> is nonzero. NOTE: does
79 * not necessarily return 1 on true. */
80static inline unsigned int
82{
83 return b[bit >> BITARRAY_SHIFT] & (1u << (bit & BITARRAY_MASK));
84}
85
86#endif /* !defined(TOR_BITARRAY_H) */
unsigned int bitarray_t
Definition: bitarray.h:30
static bitarray_t * bitarray_expand(bitarray_t *ba, unsigned int n_bits_old, unsigned int n_bits_new)
Definition: bitarray.h:43
static bitarray_t * bitarray_init_zero(unsigned int n_bits)
Definition: bitarray.h:33
static void bitarray_set(bitarray_t *b, int bit)
Definition: bitarray.h:68
static unsigned int bitarray_is_set(bitarray_t *b, int bit)
Definition: bitarray.h:81
static void bitarray_free_(bitarray_t *ba)
Definition: bitarray.h:60
static void bitarray_clear(bitarray_t *b, int bit)
Definition: bitarray.h:74
Headers for util_malloc.c.
#define tor_free(p)
Definition: malloc.h:56
Integer definitions used throughout Tor.