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/*
* File: memcmp.S
*
* Copyright 2004-2007 Analog Devices Inc.
* 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
*/
.align 2
/*
* C Library function MEMCMP
* R0 = First Address
* R1 = Second Address
* R2 = count
* Favours word aligned data.
*/
.globl _memcmp;
_memcmp:
I1 = P3;
P0 = R0; /* P0 = s1 address */
P3 = R1; /* P3 = s2 Address */
P2 = R2 ; /* P2 = count */
CC = R2 <= 7(IU);
IF CC JUMP .Ltoo_small;
I0 = R1; /* s2 */
R1 = R1 | R0; /* OR addresses together */
R1 <<= 30; /* check bottom two bits */
CC = AZ; /* AZ set if zero. */
IF !CC JUMP .Lbytes ; /* Jump if addrs not aligned. */
P1 = P2 >> 2; /* count = n/4 */
R3 = 3;
R2 = R2 & R3; /* remainder */
P2 = R2; /* set remainder */
LSETUP (.Lquad_loop_s , .Lquad_loop_e) LC0=P1;
.Lquad_loop_s:
NOP;
R0 = [P0++];
R1 = [I0++];
CC = R0 == R1;
IF !CC JUMP .Lquad_different;
.Lquad_loop_e:
NOP;
P3 = I0; /* s2 */
.Ltoo_small:
CC = P2 == 0; /* Check zero count*/
IF CC JUMP .Lfinished; /* very unlikely*/
.Lbytes:
LSETUP (.Lbyte_loop_s , .Lbyte_loop_e) LC0=P2;
.Lbyte_loop_s:
R1 = B[P3++](Z); /* *s2 */
R0 = B[P0++](Z); /* *s1 */
CC = R0 == R1;
IF !CC JUMP .Ldifferent;
.Lbyte_loop_e:
NOP;
.Ldifferent:
R0 = R0 - R1;
P3 = I1;
RTS;
.Lquad_different:
/* We've read two quads which don't match.
* Can't just compare them, because we're
* a little-endian machine, so the MSBs of
* the regs occur at later addresses in the
* string.
* Arrange to re-read those two quads again,
* byte-by-byte.
*/
P0 += -4; /* back up to the start of the */
P3 = I0; /* quads, and increase the*/
P2 += 4; /* remainder count*/
P3 += -4;
JUMP .Lbytes;
.Lfinished:
R0 = 0;
P3 = I1;
RTS;
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