arch/sh/include/asm/bitops-op32.h

Source file repositories/reference/linux-study-clean/arch/sh/include/asm/bitops-op32.h

File Facts

System
Linux kernel
Corpus path
arch/sh/include/asm/bitops-op32.h
Extension
.h
Size
3915 bytes
Lines
144
Domain
Architecture Layer
Bucket
arch/sh
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 __ASM_SH_BITOPS_OP32_H
#define __ASM_SH_BITOPS_OP32_H

#include <linux/bits.h>

/*
 * The bit modifying instructions on SH-2A are only capable of working
 * with a 3-bit immediate, which signifies the shift position for the bit
 * being worked on.
 */
#if defined(__BIG_ENDIAN)
#define BITOP_LE_SWIZZLE	((BITS_PER_LONG-1) & ~0x7)
#define BYTE_NUMBER(nr)		((nr ^ BITOP_LE_SWIZZLE) / BITS_PER_BYTE)
#define BYTE_OFFSET(nr)		((nr ^ BITOP_LE_SWIZZLE) % BITS_PER_BYTE)
#else
#define BYTE_NUMBER(nr)		((nr) / BITS_PER_BYTE)
#define BYTE_OFFSET(nr)		((nr) % BITS_PER_BYTE)
#endif

static __always_inline void
arch___set_bit(unsigned long nr, volatile unsigned long *addr)
{
	if (__builtin_constant_p(nr)) {
		__asm__ __volatile__ (
			"bset.b %1, @(%O2,%0)		! __set_bit\n\t"
			: "+r" (addr)
			: "i" (BYTE_OFFSET(nr)), "i" (BYTE_NUMBER(nr))
			: "t", "memory"
		);
	} else {
		unsigned long mask = BIT_MASK(nr);
		unsigned long *p = ((unsigned long *)addr) + BIT_WORD(nr);

		*p |= mask;
	}
}

static __always_inline void
arch___clear_bit(unsigned long nr, volatile unsigned long *addr)
{
	if (__builtin_constant_p(nr)) {
		__asm__ __volatile__ (
			"bclr.b %1, @(%O2,%0)		! __clear_bit\n\t"
			: "+r" (addr)
			: "i" (BYTE_OFFSET(nr)),
			  "i" (BYTE_NUMBER(nr))
			: "t", "memory"
		);
	} else {
		unsigned long mask = BIT_MASK(nr);
		unsigned long *p = ((unsigned long *)addr) + BIT_WORD(nr);

		*p &= ~mask;
	}
}

/**
 * arch___change_bit - Toggle a bit in memory
 * @nr: the bit to change
 * @addr: the address to start counting from
 *
 * Unlike change_bit(), this function is non-atomic and may be reordered.
 * If it's called on the same region of memory simultaneously, the effect
 * may be that only one operation succeeds.
 */
static __always_inline void
arch___change_bit(unsigned long nr, volatile unsigned long *addr)
{
	if (__builtin_constant_p(nr)) {
		__asm__ __volatile__ (
			"bxor.b %1, @(%O2,%0)		! __change_bit\n\t"
			: "+r" (addr)
			: "i" (BYTE_OFFSET(nr)),
			  "i" (BYTE_NUMBER(nr))
			: "t", "memory"
		);
	} else {
		unsigned long mask = BIT_MASK(nr);
		unsigned long *p = ((unsigned long *)addr) + BIT_WORD(nr);

		*p ^= mask;
	}
}

/**
 * arch___test_and_set_bit - Set a bit and return its old value
 * @nr: Bit to set
 * @addr: Address to count from
 *
 * This operation is non-atomic and can be reordered.

Annotation

Implementation Notes