arch/csky/abiv2/memmove.S

Source file repositories/reference/linux-study-clean/arch/csky/abiv2/memmove.S

File Facts

System
Linux kernel
Corpus path
arch/csky/abiv2/memmove.S
Extension
.S
Size
2017 bytes
Lines
105
Domain
Architecture Layer
Bucket
arch/csky
Inferred role
Architecture Layer: arch/csky
Status
atlas-only

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

// Copyright (C) 2018 Hangzhou C-SKY Microsystems co.,ltd.

#include <linux/linkage.h>
#include "sysdep.h"

	.weak memmove
ENTRY(__memmove)
ENTRY(memmove)
	subu	r3, r0, r1
	cmphs	r3, r2
	bt	memcpy

	mov	r12, r0
	addu	r0, r0, r2
	addu	r1, r1, r2

	/* Test if len less than 4 bytes.  */
	cmplti	r2, 4
	bt	.L_copy_by_byte

	andi	r13, r0, 3
	/* Test if dest is not 4 bytes aligned.  */
	bnez	r13, .L_dest_not_aligned
	/* Hardware can handle unaligned access directly.  */
.L_dest_aligned:
	/* If dest is aligned, then copy.  */
	zext	r18, r2, 31, 4
	/* Test if len less than 16 bytes.  */
	bez	r18, .L_len_less_16bytes
	movi	r19, 0

	/* len > 16 bytes */
	LABLE_ALIGN
.L_len_larger_16bytes:
	subi	r1, 16
	subi	r0, 16
#if defined(__CK860__)
	ldw	r3, (r1, 12)
	stw	r3, (r0, 12)
	ldw	r3, (r1, 8)
	stw	r3, (r0, 8)
	ldw	r3, (r1, 4)
	stw	r3, (r0, 4)
	ldw	r3, (r1, 0)
	stw	r3, (r0, 0)
#else
	ldw	r20, (r1, 0)
	ldw	r21, (r1, 4)
	ldw	r22, (r1, 8)
	ldw	r23, (r1, 12)
	stw	r20, (r0, 0)
	stw	r21, (r0, 4)
	stw	r22, (r0, 8)
	stw	r23, (r0, 12)
	PRE_BNEZAD (r18)
#endif
	BNEZAD (r18, .L_len_larger_16bytes)

.L_len_less_16bytes:
	zext	r18, r2, 3, 2
	bez	r18, .L_copy_by_byte
.L_len_less_16bytes_loop:
	subi	r1, 4
	subi	r0, 4
	ldw	r3, (r1, 0)
	PRE_BNEZAD (r18)
	stw	r3, (r0, 0)
	BNEZAD (r18, .L_len_less_16bytes_loop)

	/* Test if len less than 4 bytes.  */

Annotation

Implementation Notes