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/*
* File: arch/blackfin/lib/memcpy.S
* Based on:
* Author:
*
* Created:
* Description: internal version of memcpy(), issued by the compiler
* to copy blocks of data around.
* This is really memmove() - it has to be able to deal with
* possible overlaps, because that ambiguity is when the compiler
* gives up and calls a function. We have our own, internal version
* so that we get something we trust, even if the user has redefined
* the normal symbol.
*
* Modified:
* Copyright 2004-2006 Analog Devices Inc.
*
* Bugs: Enter bugs at http://blackfin.uclinux.org/
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program 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 General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, see the file COPYING, or write
* to the Free Software Foundation, Inc.,
* 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include <linux/linkage.h>
/* void *memcpy(void *dest, const void *src, size_t n);
* R0 = To Address (dest) (leave unchanged to form result)
* R1 = From Address (src)
* R2 = count
*
* Note: Favours word alignment
*/
#ifdef CONFIG_MEMCPY_L1
.section .l1.text
#else
.text
#endif
.align 2
ENTRY(_memcpy)
CC = R2 <= 0; /* length not positive? */
IF CC JUMP .L_P1L2147483647; /* Nothing to do */
P0 = R0 ; /* dst*/
P1 = R1 ; /* src*/
P2 = R2 ; /* length */
/* check for overlapping data */
CC = R1 < R0; /* src < dst */
IF !CC JUMP .Lno_overlap;
R3 = R1 + R2;
CC = R0 < R3; /* and dst < src+len */
IF CC JUMP .Lhas_overlap;
.Lno_overlap:
/* Check for aligned data.*/
R3 = R1 | R0;
R0 = 0x3;
R3 = R3 & R0;
CC = R3; /* low bits set on either address? */
IF CC JUMP .Lnot_aligned;
/* Both addresses are word-aligned, so we can copy
at least part of the data using word copies.*/
P2 = P2 >> 2;
CC = P2 <= 2;
IF !CC JUMP .Lmore_than_seven;
/* less than eight bytes... */
P2 = R2;
LSETUP(.Lthree_start, .Lthree_end) LC0=P2;
R0 = R1; /* setup src address for return */
.Lthree_start:
R3 = B[P1++] (X);
.Lthree_end:
B[P0++] = R3;
RTS;
.Lmore_than_seven:
/* There's at least eight bytes to copy. */
P2 += -1; /* because we unroll one iteration */
LSETUP(.Lword_loop, .Lword_loop) LC0=P2;
R0 = R1;
I1 = P1;
R3 = [I1++];
.Lword_loop:
MNOP || [P0++] = R3 || R3 = [I1++];
[P0++] = R3;
/* Any remaining bytes to copy? */
R3 = 0x3;
R3 = R2 & R3;
CC = R3 == 0;
P1 = I1; /* in case there's something left, */
IF !CC JUMP .Lbytes_left;
RTS;
.Lbytes_left: P2 = R3;
.Lnot_aligned:
/* From here, we're copying byte-by-byte. */
LSETUP (.Lbyte_start, .Lbyte_end) LC0=P2;
R0 = R1; /* Save src address for return */
.Lbyte_start:
R1 = B[P1++] (X);
.Lbyte_end:
B[P0++] = R1;
.L_P1L2147483647:
RTS;
.Lhas_overlap:
/* Need to reverse the copying, because the
* dst would clobber the src.
* Don't bother to work out alignment for
* the reverse case.
*/
R0 = R1; /* save src for later. */
P0 = P0 + P2;
P0 += -1;
P1 = P1 + P2;
P1 += -1;
LSETUP(.Lover_start, .Lover_end) LC0=P2;
.Lover_start:
R1 = B[P1--] (X);
.Lover_end:
B[P0--] = R1;
RTS;
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