arch/x86/boot/bitops.h

Source file repositories/reference/linux-study-clean/arch/x86/boot/bitops.h

File Facts

System
Linux kernel
Corpus path
arch/x86/boot/bitops.h
Extension
.h
Size
1081 bytes
Lines
45
Domain
Architecture Layer
Bucket
arch/x86
Inferred role
Architecture Layer: implementation source
Status
source implementation candidate

Why This File Exists

CPU and platform-specific kernel glue: boot entry, traps, syscall entry, interrupts, page tables, context switch, and low-level barriers.

Dependency Surface

Detected Declarations

Annotated Snippet

#ifndef BOOT_BITOPS_H
#define BOOT_BITOPS_H
#define _LINUX_BITOPS_H		/* Inhibit inclusion of <linux/bitops.h> */

#include <linux/types.h>
#include <asm/asm.h>

static inline bool constant_test_bit(int nr, const void *addr)
{
	const u32 *p = addr;
	return ((1UL << (nr & 31)) & (p[nr >> 5])) != 0;
}
static inline bool variable_test_bit(int nr, const void *addr)
{
	bool v;
	const u32 *p = addr;

	asm("btl %2,%1" : "=@ccc" (v) : "m" (*p), "Ir" (nr));
	return v;
}

#define test_bit(nr,addr) \
(__builtin_constant_p(nr) ? \
 constant_test_bit((nr),(addr)) : \
 variable_test_bit((nr),(addr)))

static inline void set_bit(int nr, void *addr)
{
	asm("btsl %1,%0" : "+m" (*(u32 *)addr) : "Ir" (nr));
}

#endif /* BOOT_BITOPS_H */

Annotation

Implementation Notes