greenplumn pg_bitutils 源码

2022-08-18
浏览 (403)

greenplumn pg_bitutils 代码

文件路径：/src/include/port/pg_bitutils.h

/*-------------------------------------------------------------------------
 *
 * pg_bitutils.h
 *	  Miscellaneous functions for bit-wise operations.
 *
 *
 * Copyright (c) 2019, PostgreSQL Global Development Group
 *
 * src/include/port/pg_bitutils.h
 *
 *-------------------------------------------------------------------------
 */
#ifndef PG_BITUTILS_H
#define PG_BITUTILS_H

extern PGDLLIMPORT const uint8 pg_leftmost_one_pos[256];
extern PGDLLIMPORT const uint8 pg_rightmost_one_pos[256];
extern PGDLLIMPORT const uint8 pg_number_of_ones[256];

/*
 * pg_leftmost_one_pos32
 *		Returns the position of the most significant set bit in "word",
 *		measured from the least significant bit.  word must not be 0.
 */
static inline int
pg_leftmost_one_pos32(uint32 word)
{
#ifdef HAVE__BUILTIN_CLZ
	Assert(word != 0);

	return 31 - __builtin_clz(word);
#else
	int			shift = 32 - 8;

	Assert(word != 0);

	while ((word >> shift) == 0)
		shift -= 8;

	return shift + pg_leftmost_one_pos[(word >> shift) & 255];
#endif							/* HAVE__BUILTIN_CLZ */
}

/*
 * pg_leftmost_one_pos64
 *		As above, but for a 64-bit word.
 */
static inline int
pg_leftmost_one_pos64(uint64 word)
{
#ifdef HAVE__BUILTIN_CLZ
	Assert(word != 0);

#if defined(HAVE_LONG_INT_64)
	return 63 - __builtin_clzl(word);
#elif defined(HAVE_LONG_LONG_INT_64)
	return 63 - __builtin_clzll(word);
#else
#error must have a working 64-bit integer datatype
#endif
#else							/* !HAVE__BUILTIN_CLZ */
	int			shift = 64 - 8;

	Assert(word != 0);

	while ((word >> shift) == 0)
		shift -= 8;

	return shift + pg_leftmost_one_pos[(word >> shift) & 255];
#endif							/* HAVE__BUILTIN_CLZ */
}

/*
 * pg_rightmost_one_pos32
 *		Returns the position of the least significant set bit in "word",
 *		measured from the least significant bit.  word must not be 0.
 */
static inline int
pg_rightmost_one_pos32(uint32 word)
{
#ifdef HAVE__BUILTIN_CTZ
	Assert(word != 0);

	return __builtin_ctz(word);
#else
	int			result = 0;

	Assert(word != 0);

	while ((word & 255) == 0)
	{
		word >>= 8;
		result += 8;
	}
	result += pg_rightmost_one_pos[word & 255];
	return result;
#endif							/* HAVE__BUILTIN_CTZ */
}

/*
 * pg_rightmost_one_pos64
 *		As above, but for a 64-bit word.
 */
static inline int
pg_rightmost_one_pos64(uint64 word)
{
#ifdef HAVE__BUILTIN_CTZ
	Assert(word != 0);

#if defined(HAVE_LONG_INT_64)
	return __builtin_ctzl(word);
#elif defined(HAVE_LONG_LONG_INT_64)
	return __builtin_ctzll(word);
#else
#error must have a working 64-bit integer datatype
#endif
#else							/* !HAVE__BUILTIN_CTZ */
	int			result = 0;

	Assert(word != 0);

	while ((word & 255) == 0)
	{
		word >>= 8;
		result += 8;
	}
	result += pg_rightmost_one_pos[word & 255];
	return result;
#endif							/* HAVE__BUILTIN_CTZ */
}

/* Count the number of one-bits in a uint32 or uint64 */
extern int	(*pg_popcount32) (uint32 word);
extern int	(*pg_popcount64) (uint64 word);

/* Count the number of one-bits in a byte array */
extern uint64 pg_popcount(const char *buf, int bytes);

#endif							/* PG_BITUTILS_H */

相关信息

greenplumn 源码目录

相关文章

greenplumn aix 源码

greenplumn atomics 源码

greenplumn cygwin 源码

greenplumn darwin 源码

greenplumn freebsd 源码

greenplumn hpux 源码

greenplumn linux 源码

greenplumn netbsd 源码

greenplumn openbsd 源码

greenplumn pg_bswap 源码

0 赞

所属分类： 大数据
本文标签： greenplum
版权声明： 原创文章如转载，请注明本文链接: https://www.seaxiang.com/blog/a9be98cf3139405f826ef56589b1aaa3

热门推荐

1、直接访问google.com
2、 - 优质文章
3、 gate.io
4、 harmony 鸿蒙hdc使用指导
5、 harmony 鸿蒙初识ArkTS语言
6、 harmony 鸿蒙ArkUI组件（ArkTS）开发常见问题
7、 flink kafka connector scan.startup.mode 的几个选项
8、 golang
9、 openharmony
10、 Vue中input框自动聚焦

Loading...