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/*
* File: memset.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 MEMSET
* R0 = address (leave unchanged to form result)
* R1 = filler byte
* R2 = count
* Favours word aligned data.
*/
.globl _memset;
_memset:
P0 = R0 ; /* P0 = address */
P2 = R2 ; /* P2 = count */
R3 = R0 + R2; /* end */
CC = R2 <= 7(IU);
IF CC JUMP .Ltoo_small;
R1 = R1.B (Z); /* R1 = fill char */
R2 = 3;
R2 = R0 & R2; /* addr bottom two bits */
CC = R2 == 0; /* AZ set if zero. */
IF !CC JUMP .Lforce_align ; /* Jump if addr not aligned. */
.Laligned:
P1 = P2 >> 2; /* count = n/4 */
R2 = R1 << 8; /* create quad filler */
R2.L = R2.L + R1.L(NS);
R2.H = R2.L + R1.H(NS);
P2 = R3;
LSETUP (.Lquad_loop , .Lquad_loop) LC0=P1;
.Lquad_loop:
[P0++] = R2;
CC = P0 == P2;
IF !CC JUMP .Lbytes_left;
RTS;
.Lbytes_left:
R2 = R3; /* end point */
R3 = P0; /* current position */
R2 = R2 - R3; /* bytes left */
P2 = R2;
.Ltoo_small:
CC = P2 == 0; /* Check zero count */
IF CC JUMP .Lfinished; /* Unusual */
.Lbytes:
LSETUP (.Lbyte_loop , .Lbyte_loop) LC0=P2;
.Lbyte_loop:
B[P0++] = R1;
.Lfinished:
RTS;
.Lforce_align:
CC = BITTST (R0, 0); /* odd byte */
R0 = 4;
R0 = R0 - R2;
P1 = R0;
R0 = P0; /* Recover return address */
IF !CC JUMP .Lskip1;
B[P0++] = R1;
.Lskip1:
CC = R2 <= 2; /* 2 bytes */
P2 -= P1; /* reduce count */
IF !CC JUMP .Laligned;
B[P0++] = R1;
B[P0++] = R1;
JUMP .Laligned;
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