arch/arc/lib/memcpy-archs.S

Source file repositories/reference/linux-study-clean/arch/arc/lib/memcpy-archs.S

File Facts

System
Linux kernel
Corpus path
arch/arc/lib/memcpy-archs.S
Extension
.S
Size
4405 bytes
Lines
220
Domain
Architecture Layer
Bucket
arch/arc
Inferred role
Architecture Layer: arch/arc
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

#include <linux/linkage.h>

#ifdef __LITTLE_ENDIAN__
# define SHIFT_1(RX,RY,IMM)	asl	RX, RY, IMM	; <<
# define SHIFT_2(RX,RY,IMM)	lsr	RX, RY, IMM	; >>
# define MERGE_1(RX,RY,IMM)	asl	RX, RY, IMM
# define MERGE_2(RX,RY,IMM)
# define EXTRACT_1(RX,RY,IMM)	and	RX, RY, 0xFFFF
# define EXTRACT_2(RX,RY,IMM)	lsr	RX, RY, IMM
#else
# define SHIFT_1(RX,RY,IMM)	lsr	RX, RY, IMM	; >>
# define SHIFT_2(RX,RY,IMM)	asl	RX, RY, IMM	; <<
# define MERGE_1(RX,RY,IMM)	asl	RX, RY, IMM	; <<
# define MERGE_2(RX,RY,IMM)	asl	RX, RY, IMM	; <<
# define EXTRACT_1(RX,RY,IMM)	lsr	RX, RY, IMM
# define EXTRACT_2(RX,RY,IMM)	lsr	RX, RY, 0x08
#endif

#ifdef CONFIG_ARC_HAS_LL64
# define LOADX(DST,RX)		ldd.ab	DST, [RX, 8]
# define STOREX(SRC,RX)		std.ab	SRC, [RX, 8]
# define ZOLSHFT		5
# define ZOLAND			0x1F
#else
# define LOADX(DST,RX)		ld.ab	DST, [RX, 4]
# define STOREX(SRC,RX)		st.ab	SRC, [RX, 4]
# define ZOLSHFT		4
# define ZOLAND			0xF
#endif

ENTRY_CFI(memcpy)
	mov.f	0, r2
;;; if size is zero
	jz.d	[blink]
	mov	r3, r0		; don;t clobber ret val

;;; if size <= 8
	cmp	r2, 8
	bls.d	@.Lsmallchunk
	mov.f	lp_count, r2

	and.f	r4, r0, 0x03
	rsub	lp_count, r4, 4
	lpnz	@.Laligndestination
	;; LOOP BEGIN
	ldb.ab	r5, [r1,1]
	sub	r2, r2, 1
	stb.ab	r5, [r3,1]
.Laligndestination:

;;; Check the alignment of the source
	and.f	r4, r1, 0x03
	bnz.d	@.Lsourceunaligned

;;; CASE 0: Both source and destination are 32bit aligned
;;; Convert len to Dwords, unfold x4
	lsr.f	lp_count, r2, ZOLSHFT
	lpnz	@.Lcopy32_64bytes
	;; LOOP START
	LOADX (r6, r1)
	LOADX (r8, r1)
	LOADX (r10, r1)
	LOADX (r4, r1)
	STOREX (r6, r3)
	STOREX (r8, r3)
	STOREX (r10, r3)
	STOREX (r4, r3)
.Lcopy32_64bytes:

	and.f	lp_count, r2, ZOLAND ;Last remaining 31 bytes

Annotation

Implementation Notes