arch/nios2/lib/memcpy.c

Source file repositories/reference/linux-study-clean/arch/nios2/lib/memcpy.c

File Facts

System
Linux kernel
Corpus path
arch/nios2/lib/memcpy.c
Extension
.c
Size
6065 bytes
Lines
203
Domain
Architecture Layer
Bucket
arch/nios2
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

Copyright (C) 1991, 1992, 1993, 1997, 2004 Free Software Foundation, Inc.
   This file is part of the GNU C Library.
   Contributed by Torbjorn Granlund (tege@sics.se).

   The GNU C Library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Lesser General Public
   License as published by the Free Software Foundation; either
   version 2.1 of the License, or (at your option) any later version.

   The GNU C Library is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public
   License along with the GNU C Library; if not, see
   <http://www.gnu.org/licenses/>.  */

#include <linux/types.h>

/* Type to use for aligned memory operations.
   This should normally be the biggest type supported by a single load
   and store.  */
#define	op_t	unsigned long int
#define OPSIZ	(sizeof(op_t))

/* Optimal type for storing bytes in registers.  */
#define	reg_char	char

#define MERGE(w0, sh_1, w1, sh_2) (((w0) >> (sh_1)) | ((w1) << (sh_2)))

/* Copy exactly NBYTES bytes from SRC_BP to DST_BP,
   without any assumptions about alignment of the pointers.  */
#define BYTE_COPY_FWD(dst_bp, src_bp, nbytes)				\
do {									\
	size_t __nbytes = (nbytes);					\
	while (__nbytes > 0) {						\
		unsigned char __x = ((unsigned char *) src_bp)[0];	\
		src_bp += 1;						\
		__nbytes -= 1;						\
		((unsigned char *) dst_bp)[0] = __x;			\
		dst_bp += 1;						\
	}								\
} while (0)

/* Copy *up to* NBYTES bytes from SRC_BP to DST_BP, with
   the assumption that DST_BP is aligned on an OPSIZ multiple.  If
   not all bytes could be easily copied, store remaining number of bytes
   in NBYTES_LEFT, otherwise store 0.  */
/* extern void _wordcopy_fwd_aligned __P ((long int, long int, size_t)); */
/* extern void _wordcopy_fwd_dest_aligned __P ((long int, long int, size_t)); */
#define WORD_COPY_FWD(dst_bp, src_bp, nbytes_left, nbytes)		\
do {									\
	if (src_bp % OPSIZ == 0)					\
		_wordcopy_fwd_aligned(dst_bp, src_bp, (nbytes) / OPSIZ);\
	else								\
		_wordcopy_fwd_dest_aligned(dst_bp, src_bp, (nbytes) / OPSIZ);\
	src_bp += (nbytes) & -OPSIZ;					\
	dst_bp += (nbytes) & -OPSIZ;					\
	(nbytes_left) = (nbytes) % OPSIZ;				\
} while (0)


/* Threshold value for when to enter the unrolled loops.  */
#define	OP_T_THRES	16

/* _wordcopy_fwd_aligned -- Copy block beginning at SRCP to
   block beginning at DSTP with LEN `op_t' words (not LEN bytes!).
   Both SRCP and DSTP should be aligned for memory operations on `op_t's.  */
/* stream-lined (read x8 + write x8) */
static void _wordcopy_fwd_aligned(long int dstp, long int srcp, size_t len)
{
	while (len > 7) {
		register op_t a0, a1, a2, a3, a4, a5, a6, a7;

		a0 = ((op_t *) srcp)[0];
		a1 = ((op_t *) srcp)[1];
		a2 = ((op_t *) srcp)[2];
		a3 = ((op_t *) srcp)[3];
		a4 = ((op_t *) srcp)[4];
		a5 = ((op_t *) srcp)[5];
		a6 = ((op_t *) srcp)[6];
		a7 = ((op_t *) srcp)[7];
		((op_t *) dstp)[0] = a0;
		((op_t *) dstp)[1] = a1;
		((op_t *) dstp)[2] = a2;
		((op_t *) dstp)[3] = a3;
		((op_t *) dstp)[4] = a4;
		((op_t *) dstp)[5] = a5;
		((op_t *) dstp)[6] = a6;

Annotation

Implementation Notes