thodg/libgit2/src/util/bitvec.h

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• Hash : c3b7ace9
  Author :
  Date : 2021-11-14T16:43:53
  

  refactor: make util an object library Instead of simply including the utility files directly, make them a cmake object library for easy reusability between other projects within libgit2. Now the top-level `src` is responsible for platform selection, while the next-level `libgit2` and `util` configurations are responsible for identifying what objects they include.

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• src/util/bitvec.h

• /*
   * 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
  

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