/*

 * Copyright (C) the libgit2 contributors. All rights reserved.

 *

 * This file is part of libgit2, distributed under the GNU GPL v2 with

 * a Linking Exception. For full terms see the included COPYING file.

 */

#ifndef INCLUDE_bitvec_h__

#define INCLUDE_bitvec_h__

#include "common.h"

/*

 * This is a silly little fixed length bit vector type that will store

 * vectors of 64 bits or less directly in the structure and allocate

 * memory for vectors longer than 64 bits.  You can use the two versions

 * transparently through the API and avoid heap allocation completely when

 * using a short bit vector as a result.

 */

typedef struct {

  size_t length;

  union {

    uint64_t *words;

    uint64_t bits;

  } u;

} git_bitvec;

GIT_INLINE(int) git_bitvec_init(git_bitvec *bv, size_t capacity)

{

  memset(bv, 0x0, sizeof(*bv));

  if (capacity >= 64) {

    bv->length = (capacity / 64) + 1;

    bv->u.words = git__calloc(bv->length, sizeof(uint64_t));

    if (!bv->u.words)

      return -1;

  }

  return 0;

}

#define GIT_BITVEC_MASK(BIT) ((uint64_t)1 << (BIT % 64))

#define GIT_BITVEC_WORD(BV, BIT) (BV->length ? &BV->u.words[BIT / 64] : &BV->u.bits)

GIT_INLINE(void) git_bitvec_set(git_bitvec *bv, size_t bit, bool on)

{

  uint64_t *word = GIT_BITVEC_WORD(bv, bit);

  uint64_t mask = GIT_BITVEC_MASK(bit);

  if (on)

    *word |= mask;

  else

    *word &= ~mask;

}

GIT_INLINE(bool) git_bitvec_get(git_bitvec *bv, size_t bit)

{

  uint64_t *word = GIT_BITVEC_WORD(bv, bit);

  return (*word & GIT_BITVEC_MASK(bit)) != 0;

}

GIT_INLINE(void) git_bitvec_clear(git_bitvec *bv)

{

  if (!bv->length)

    bv->u.bits = 0;

  else

    memset(bv->u.words, 0x0, bv->length * sizeof(uint64_t));

}

GIT_INLINE(void) git_bitvec_free(git_bitvec *bv)

{

  if (bv->length)

    git__free(bv->u.words);

}

#endif