include/asm-generic/bitsperlong.h

Source file repositories/reference/linux-study-clean/include/asm-generic/bitsperlong.h

File Facts

System
Linux kernel
Corpus path
include/asm-generic/bitsperlong.h
Extension
.h
Size
1466 bytes
Lines
48
Domain
Repository Root And Misc
Bucket
include
Inferred role
Repository Root And Misc: implementation source
Status
source implementation candidate

Why This File Exists

Top-level or miscellaneous repository surface. Use this as map coverage unless a later manual pass promotes the file into a deeper subsystem dossier.

Dependency Surface

Detected Declarations

Annotated Snippet

#ifndef __ASM_GENERIC_BITS_PER_LONG
#define __ASM_GENERIC_BITS_PER_LONG

#include <uapi/asm-generic/bitsperlong.h>


#ifdef CONFIG_64BIT
#define BITS_PER_LONG 64
#else
#define BITS_PER_LONG 32
#endif /* CONFIG_64BIT */

/*
 * FIXME: The check currently breaks x86-64 build, so it's
 * temporarily disabled. Please fix x86-64 and reenable
 */
#if 0 && BITS_PER_LONG != __BITS_PER_LONG
#error Inconsistent word size. Check asm/bitsperlong.h
#endif

#if __CHAR_BIT__ * __SIZEOF_LONG__ != __BITS_PER_LONG
#error Inconsistent word size. Check asm/bitsperlong.h
#endif

#ifndef __ASSEMBLER__
_Static_assert(sizeof(long) * 8 == __BITS_PER_LONG,
	       "Inconsistent word size. Check asm/bitsperlong.h");
#endif

#ifndef BITS_PER_LONG_LONG
#define BITS_PER_LONG_LONG 64
#endif

/*
 * small_const_nbits(n) is true precisely when it is known at compile-time
 * that BITMAP_SIZE(n) is 1, i.e. 1 <= n <= BITS_PER_LONG. This allows
 * various bit/bitmap APIs to provide a fast inline implementation. Bitmaps
 * of size 0 are very rare, and a compile-time-known-size 0 is most likely
 * a sign of error. They will be handled correctly by the bit/bitmap APIs,
 * but using the out-of-line functions, so that the inline implementations
 * can unconditionally dereference the pointer(s).
 */
#define small_const_nbits(nbits) \
	(__builtin_constant_p(nbits) && (nbits) <= BITS_PER_LONG && (nbits) > 0)

#endif /* __ASM_GENERIC_BITS_PER_LONG */

Annotation

Implementation Notes