arch/xtensa/include/asm/asmmacro.h

Source file repositories/reference/linux-study-clean/arch/xtensa/include/asm/asmmacro.h

File Facts

System
Linux kernel
Corpus path
arch/xtensa/include/asm/asmmacro.h
Extension
.h
Size
6829 bytes
Lines
341
Domain
Architecture Layer
Bucket
arch/xtensa
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 _XTENSA_ASMMACRO_H
#define _XTENSA_ASMMACRO_H

#include <linux/export.h>
#include <asm/core.h>

/*
 * Some little helpers for loops. Use zero-overhead-loops
 * where applicable and if supported by the processor.
 *
 * __loopi ar, at, size, inc
 *         ar	register initialized with the start address
 *	   at	scratch register used by macro
 *	   size	size immediate value
 *	   inc	increment
 *
 * __loops ar, as, at, inc_log2[, mask_log2][, cond][, ncond]
 *	   ar	register initialized with the start address
 *	   as	register initialized with the size
 *	   at	scratch register use by macro
 *	   inc_log2	increment [in log2]
 *	   mask_log2	mask [in log2]
 *	   cond		true condition (used in loop'cond')
 *	   ncond	false condition (used in b'ncond')
 *
 * __loop  as
 *	   restart loop. 'as' register must not have been modified!
 *
 * __endla ar, as, incr
 *	   ar	start address (modified)
 *	   as	scratch register used by __loops/__loopi macros or
 *		end address used by __loopt macro
 *	   inc	increment
 */

/*
 * loop for given size as immediate
 */

	.macro	__loopi ar, at, size, incr

#if XCHAL_HAVE_LOOPS
		movi	\at, ((\size + \incr - 1) / (\incr))
		loop	\at, 99f
#else
		addi	\at, \ar, \size
		98:
#endif

	.endm

/*
 * loop for given size in register
 */

	.macro	__loops	ar, as, at, incr_log2, mask_log2, cond, ncond

#if XCHAL_HAVE_LOOPS
		.ifgt \incr_log2 - 1
			addi	\at, \as, (1 << \incr_log2) - 1
			.ifnc \mask_log2,
				extui	\at, \at, \incr_log2, \mask_log2
			.else
				srli	\at, \at, \incr_log2
			.endif
		.endif
		loop\cond	\at, 99f
#else
		.ifnc \mask_log2,
			extui	\at, \as, \incr_log2, \mask_log2
		.else
			.ifnc \ncond,
				srli	\at, \as, \incr_log2
			.endif
		.endif
		.ifnc \ncond,
			b\ncond	\at, 99f

		.endif
		.ifnc \mask_log2,
			slli	\at, \at, \incr_log2
			add	\at, \ar, \at
		.else
			add	\at, \ar, \as
		.endif
#endif
		98:

	.endm

Annotation

Implementation Notes