flexnbd-c/bitset.h

#ifndef __BITSET_H
#define __BITSET_H

#include <inttypes.h>
#include <string.h>
#include <pthread.h>

#include "util.h"

static inline char char_with_bit_set(int num) { return 1<<(num%8); }

static inline int bit_is_set(char* b, int idx) {
	return (b[idx/8] & char_with_bit_set(idx)) != 0;
}
static inline int bit_is_clear(char* b, int idx) {
	return !bit_is_set(b, idx);
}
static inline int bit_has_value(char* b, int idx, int value) {
	if (value)
		return bit_is_set(b, idx);
	else
		return bit_is_clear(b, idx);
}
static inline void bit_set(char* b, int idx) {
	b[idx/8] |= char_with_bit_set(idx);
	//__sync_fetch_and_or(b+(idx/8), char_with_bit_set(idx));
}
static inline void bit_clear(char* b, int idx) {
	b[idx/8] &= ~char_with_bit_set(idx);
	//__sync_fetch_and_nand(b+(idx/8), char_with_bit_set(idx));
}
static inline void bit_set_range(char* b, int from, int len) {
	for (; from%8 != 0 && len > 0; len--)
		bit_set(b, from++);
	if (len >= 8)
		memset(b+(from/8), 255, len/8);
	for (; len > 0; len--)
		bit_set(b, from++);
}
static inline void bit_clear_range(char* b, int from, int len) {
	for (; from%8 != 0 && len > 0; len--)
		bit_clear(b, from++);
	if (len >= 8)
		memset(b+(from/8), 0, len/8);
	for (; len > 0; len--)
		bit_clear(b, from++);
}

static inline int bit_run_count(char* b, int from, int len) {
	int count;
	int first_value = bit_is_set(b, from);

	for (count=0; len > 0 && bit_has_value(b, from+count, first_value); count++, len--)
		;

	/* FIXME: debug this later */
	/*for (; (from+count) % 64 != 0 && len > 0; len--)
		if (bit_has_value(b, from+count, first_value))
			count++;
		else
			return count;
	for (; len >= 64; len-=64) {
		if (*((uint64_t*)(b + ((from+count)/8))) == UINT64_MAX)
			count += 64;
		else
			break;
	}
	for (; len > 0; len--)
		if (bit_is_set(b, from+count))
			count++;*/

	return count;
}

struct bitset_mapping {
	uint64_t size;
	int resolution;
	char bits[];
};

static inline struct bitset_mapping* bitset_alloc(
	uint64_t size, 
	int resolution
)
{
	struct bitset_mapping *bitset = xmalloc(
		sizeof(struct bitset_mapping)+
		(size+resolution-1)/resolution
	);
	bitset->size = size;
	bitset->resolution = resolution;
	return bitset;
}

#define INT_FIRST_AND_LAST \
  int first = from/set->resolution, \
      last = (from+len-1)/set->resolution, \
      bitlen = last-first+1

static inline void bitset_set_range(
	struct bitset_mapping* set, 
	uint64_t from, 
	uint64_t len)
{
	INT_FIRST_AND_LAST;
	bit_set_range(set->bits, first, bitlen);
}

static inline void bitset_clear_range(
	struct bitset_mapping* set, 
	uint64_t from, 
	uint64_t len)
{
	INT_FIRST_AND_LAST;
	bit_clear_range(set->bits, first, bitlen);
}

static inline int bitset_run_count(
	struct bitset_mapping* set, 
	uint64_t from, 
	uint64_t len)
{
	INT_FIRST_AND_LAST;
	return bit_run_count(set->bits, first, bitlen) * set->resolution;
}

static inline int bitset_is_clear_at(
	struct bitset_mapping* set,
	uint64_t at
)
{
	return bit_is_clear(set->bits, at/set->resolution);
}

static inline int bitset_is_set_at(
	struct bitset_mapping* set,
	uint64_t at
)
{
	return bit_is_set(set->bits, at/set->resolution);
}


#endif