arch/blackfin/lib/memset.S

   1 /*
   2  * File:         arch/blackfin/lib/memset.S
   3  * Based on:
   4  * Author:
   5  *
   6  * Created:
   7  * Description:
   8  *
   9  * Modified:
  10  *               Copyright 2004-2006 Analog Devices Inc.
  11  *
  12  * Bugs:         Enter bugs at http://blackfin.uclinux.org/
  13  *
  14  * This program is free software; you can redistribute it and/or modify
  15  * it under the terms of the GNU General Public License as published by
  16  * the Free Software Foundation; either version 2 of the License, or
  17  * (at your option) any later version.
  18  *
  19  * This program is distributed in the hope that it will be useful,
  20  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  21  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  22  * GNU General Public License for more details.
  23  *
  24  * You should have received a copy of the GNU General Public License
  25  * along with this program; if not, see the file COPYING, or write
  26  * to the Free Software Foundation, Inc.,
  27  * 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
  28  */
  29
  30 #include <linux/linkage.h>
  31
  32 .align 2
  33
  34 #ifdef CONFIG_MEMSET_L1
  35 .section .l1.text
  36 #else
  37 .text
  38 #endif
  39
  40 /*
  41  * C Library function MEMSET
  42  * R0 = address (leave unchanged to form result)
  43  * R1 = filler byte
  44  * R2 = count
  45  * Favours word aligned data.
  46  */
  47
  48 ENTRY(_memset)
  49         P0 = R0 ;              /* P0 = address */
  50         P2 = R2 ;              /* P2 = count   */
  51         R3 = R0 + R2;          /* end          */
  52         CC = R2 <= 7(IU);
  53         IF CC JUMP  .Ltoo_small;
  54         R1 = R1.B (Z);         /* R1 = fill char */
  55         R2 =  3;
  56         R2 = R0 & R2;          /* addr bottom two bits */
  57         CC =  R2 == 0;             /* AZ set if zero.   */
  58         IF !CC JUMP  .Lforce_align ;  /* Jump if addr not aligned. */
  59
  60 .Laligned:
  61         P1 = P2 >> 2;          /* count = n/4        */
  62         R2 = R1 <<  8;         /* create quad filler */
  63         R2.L = R2.L + R1.L(NS);
  64         R2.H = R2.L + R1.H(NS);
  65         P2 = R3;
  66
  67         LSETUP (.Lquad_loop , .Lquad_loop) LC0=P1;
  68 .Lquad_loop:
  69         [P0++] = R2;
  70
  71         CC = P0 == P2;
  72         IF !CC JUMP .Lbytes_left;
  73         RTS;
  74
  75 .Lbytes_left:
  76         R2 = R3;                /* end point */
  77         R3 = P0;                /* current position */
  78         R2 = R2 - R3;           /* bytes left */
  79         P2 = R2;
  80
  81 .Ltoo_small:
  82         CC = P2 == 0;           /* Check zero count */
  83         IF CC JUMP .Lfinished;    /* Unusual */
  84
  85 .Lbytes:
  86         LSETUP (.Lbyte_loop , .Lbyte_loop) LC0=P2;
  87 .Lbyte_loop:
  88         B[P0++] = R1;
  89
  90 .Lfinished:
  91         RTS;
  92
  93 .Lforce_align:
  94         CC = BITTST (R0, 0);  /* odd byte */
  95         R0 = 4;
  96         R0 = R0 - R2;
  97         P1 = R0;
  98         R0 = P0;                    /* Recover return address */
  99         IF !CC JUMP .Lskip1;
 100         B[P0++] = R1;
 101 .Lskip1:
 102         CC = R2 <= 2;          /* 2 bytes */
 103         P2 -= P1;              /* reduce count */
 104         IF !CC JUMP .Laligned;
 105         B[P0++] = R1;
 106         B[P0++] = R1;
 107         JUMP .Laligned;
 108
 109 .size _memset,.-_memset