1/*
2 * File:         arch/blackfin/lib/memcpy.S
3 * Based on:
4 * Author:
5 *
6 * Created:
7 * Description:  internal version of memcpy(), issued by the compiler
8 *               to copy blocks of data around.
9 *               This is really memmove() - it has to be able to deal with
10 *               possible overlaps, because that ambiguity is when the compiler
11 *               gives up and calls a function. We have our own, internal version
12 *               so that we get something we trust, even if the user has redefined
13 *               the normal symbol.
14 *
15 * Modified:
16 *               Copyright 2004-2006 Analog Devices Inc.
17 *
18 * Bugs:         Enter bugs at http://blackfin.uclinux.org/
19 *
20 * This program is free software; you can redistribute it and/or modify
21 * it under the terms of the GNU General Public License as published by
22 * the Free Software Foundation; either version 2 of the License, or
23 * (at your option) any later version.
24 *
25 * This program is distributed in the hope that it will be useful,
26 * but WITHOUT ANY WARRANTY; without even the implied warranty of
27 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
28 * GNU General Public License for more details.
29 *
30 * You should have received a copy of the GNU General Public License
31 * along with this program; if not, see the file COPYING, or write
32 * to the Free Software Foundation, Inc.,
33 * 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
34 */
35
36#include <linux/linkage.h>
37
38/* void *memcpy(void *dest, const void *src, size_t n);
39 * R0 = To Address (dest) (leave unchanged to form result)
40 * R1 = From Address (src)
41 * R2 = count
42 *
43 * Note: Favours word alignment
44 */
45
46#ifdef CONFIG_MEMCPY_L1
47.section .l1.text
48#else
49.text
50#endif
51
52.align 2
53
54ENTRY(_memcpy)
55	CC = R2 <=  0;	/* length not positive? */
56	IF CC JUMP .L_P1L2147483647;	/* Nothing to do */
57
58	P0 = R0 ;	/* dst*/
59	P1 = R1 ;	/* src*/
60	P2 = R2 ;	/* length */
61
62	/* check for overlapping data */
63	CC = R1 < R0;	/* src < dst */
64	IF !CC JUMP .Lno_overlap;
65	R3 = R1 + R2;
66	CC = R0 < R3;	/* and dst < src+len */
67	IF CC JUMP .Lhas_overlap;
68
69.Lno_overlap:
70	/* Check for aligned data.*/
71
72	R3 = R1 | R0;
73	R0 = 0x3;
74	R3 = R3 & R0;
75	CC = R3;	/* low bits set on either address? */
76	IF CC JUMP .Lnot_aligned;
77
78	/* Both addresses are word-aligned, so we can copy
79	at least part of the data using word copies.*/
80	P2 = P2 >> 2;
81	CC = P2 <= 2;
82	IF !CC JUMP .Lmore_than_seven;
83	/* less than eight bytes... */
84	P2 = R2;
85	LSETUP(.Lthree_start, .Lthree_end) LC0=P2;
86	R0 = R1;	/* setup src address for return */
87.Lthree_start:
88	R3 = B[P1++] (X);
89.Lthree_end:
90	B[P0++] = R3;
91
92	RTS;
93
94.Lmore_than_seven:
95	/* There's at least eight bytes to copy. */
96	P2 += -1;	/* because we unroll one iteration */
97	LSETUP(.Lword_loops, .Lword_loope) LC0=P2;
98	R0 = R1;
99	I1 = P1;
100	R3 = [I1++];
101#ifdef ANOMALY_05000202
102.Lword_loops:
103	[P0++] = R3;
104.Lword_loope:
105	R3 = [I1++];
106#else
107.Lword_loops:
108.Lword_loope:
109	MNOP || [P0++] = R3 || R3 = [I1++];
110#endif
111	[P0++] = R3;
112	/* Any remaining bytes to copy? */
113	R3 = 0x3;
114	R3 = R2 & R3;
115	CC = R3 == 0;
116	P1 = I1;	/* in case there's something left, */
117	IF !CC JUMP .Lbytes_left;
118	RTS;
119.Lbytes_left:	P2 = R3;
120.Lnot_aligned:
121	/* From here, we're copying byte-by-byte. */
122	LSETUP (.Lbyte_start, .Lbyte_end) LC0=P2;
123	R0 = R1;	/* Save src address for return */
124.Lbyte_start:
125	R1 = B[P1++] (X);
126.Lbyte_end:
127	B[P0++] = R1;
128
129.L_P1L2147483647:
130	RTS;
131
132.Lhas_overlap:
133	/* Need to reverse the copying, because the
134	 * dst would clobber the src.
135	 * Don't bother to work out alignment for
136	 * the reverse case.
137	 */
138	R0 = R1;	/* save src for later. */
139	P0 = P0 + P2;
140	P0 += -1;
141	P1 = P1 + P2;
142	P1 += -1;
143	LSETUP(.Lover_start, .Lover_end) LC0=P2;
144.Lover_start:
145	R1 = B[P1--] (X);
146.Lover_end:
147	B[P0--] = R1;
148
149	RTS;
150
151ENDPROC(_memcpy)
152