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bitops: merged bitset functions and cleaned up code

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S.J.R. van Schaik 2017-05-18 17:16:48 +02:00
parent 5a8bf83c7b
commit 57f72ea5f5
4 changed files with 61 additions and 71 deletions
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7
include/bitops.h
View file

@ -1,3 +1,10 @@
#pragma once #pragma once
#include <stdlib.h>
unsigned ilog2(unsigned n); unsigned ilog2(unsigned n);
int is_bit_set(void *base, size_t n);
void set_bit(void *base, size_t n);
void clear_bit(void *base, size_t n);
size_t next_set_bit(void *base, size_t n);
size_t next_clear_bit(void *base, size_t n);

10
include/bitset.h
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@ -1,10 +0,0 @@
#pragma once
#include <stdint.h>
#include <stdlib.h>
int is_bit_set(void *set, size_t n);
void set_bit(void *set, size_t n);
void clear_bit(void *set, size_t n);
size_t next_set_bit(void *set, size_t len);
size_t next_clear_bit(void *set, size_t len);

54
source/bitops.c
View file

@ -1,4 +1,10 @@
#include <stdint.h>
#include <bitops.h> #include <bitops.h>
#include <macros.h>
#define BIT_WORD(n) ((n) / BIT_SIZE(unsigned long))
#define BIT_MASK(n) (1UL << ((n) % BIT_SIZE(unsigned long)))
unsigned ilog2(unsigned n) unsigned ilog2(unsigned n)
{ {
@ -9,3 +15,51 @@ unsigned ilog2(unsigned n)
return ret; return ret;
} }
int is_bit_set(void *base, size_t n)
{
unsigned long *word = (unsigned long *)base + BIT_WORD(n);
unsigned long mask = BIT_MASK(n);
return (*word & mask) ? 1 : 0;
}
void set_bit(void *base, size_t n)
{
unsigned long *word = (unsigned long *)base + BIT_WORD(n);
unsigned long mask = BIT_MASK(n);
*word |= mask;
}
void clear_bit(void *base, size_t n)
{
unsigned long *word = (unsigned long *)base + BIT_WORD(n);
unsigned long mask = BIT_MASK(n);
*word &= ~mask;
}
size_t next_set_bit(void *base, size_t n)
{
size_t i;
for (i = 0; i < n; ++i) {
if (is_bit_set(base, i))
return i;
}
return SIZE_MAX;
}
size_t next_clear_bit(void *base, size_t n)
{
size_t i;
for (i = 0; i < n; ++i) {
if (!is_bit_set(base, i))
return i;
}
return SIZE_MAX;
}

61
source/bitset.c
View file

@ -1,61 +0,0 @@
#include <bitset.h>
#include <macros.h>
int is_bit_set(void *set_, size_t n)
{
uint8_t *set = set_;
uint8_t *word, mask;
word = set + n / BIT_SIZE(*set);
mask = (1 << (n % BIT_SIZE(*set)));
return (*word & mask) ? 1 : 0;
}
void set_bit(void *set_, size_t n)
{
uint8_t *set = set_;
uint8_t *word, mask;
word = set + n / BIT_SIZE(*set);
mask = (1 << (n % BIT_SIZE(*set)));
*word |= mask;
}
void clear_bit(void *set_, size_t n)
{
uint8_t *set = set_;
uint8_t *word, mask;
word = set + n / BIT_SIZE(*set);
mask = (1 << (n % BIT_SIZE(*set)));
*word &= ~mask;
}
size_t next_set_bit(void *set_, size_t len)
{
uint8_t *set = set_;
size_t n;
for (n = 0; n < len; ++n) {
if (is_bit_set(set, n))
return n;
}
return SIZE_MAX;
}
size_t next_clear_bit(void *set_, size_t len)
{
uint8_t *set = set_;
size_t n;
for (n = 0; n < len; ++n) {
if (!is_bit_set(set, n))
return n;
}
return SIZE_MAX;
}