arch/blackfin/lib/memset.S

   1 /*
   2  * Copyright 2004-2009 Analog Devices Inc.
   3  *
   4  * Licensed under the ADI BSD license or the GPL-2 (or later)
   5  */
   6
   7 #include <linux/linkage.h>
   8
   9 .align 2
  10
  11 #ifdef CONFIG_MEMSET_L1
  12 .section .l1.text
  13 #else
  14 .text
  15 #endif
  16
  17 /*
  18  * C Library function MEMSET
  19  * R0 = address (leave unchanged to form result)
  20  * R1 = filler byte
  21  * R2 = count
  22  * Favours word aligned data.
  23  * The strncpy assumes that I0 and I1 are not used in this function
  24  */
  25
  26 ENTRY(_memset)
  27         P0 = R0 ;              /* P0 = address */
  28         P2 = R2 ;              /* P2 = count   */
  29         R3 = R0 + R2;          /* end          */
  30         CC = R2 <= 7(IU);
  31         IF CC JUMP  .Ltoo_small;
  32         R1 = R1.B (Z);         /* R1 = fill char */
  33         R2 =  3;
  34         R2 = R0 & R2;          /* addr bottom two bits */
  35         CC =  R2 == 0;             /* AZ set if zero.   */
  36         IF !CC JUMP  .Lforce_align ;  /* Jump if addr not aligned. */
  37
  38 .Laligned:
  39         P1 = P2 >> 2;          /* count = n/4        */
  40         R2 = R1 <<  8;         /* create quad filler */
  41         R2.L = R2.L + R1.L(NS);
  42         R2.H = R2.L + R1.H(NS);
  43         P2 = R3;
  44
  45         LSETUP (.Lquad_loop , .Lquad_loop) LC0=P1;
  46 .Lquad_loop:
  47         [P0++] = R2;
  48
  49         CC = P0 == P2;
  50         IF !CC JUMP .Lbytes_left;
  51         RTS;
  52
  53 .Lbytes_left:
  54         R2 = R3;                /* end point */
  55         R3 = P0;                /* current position */
  56         R2 = R2 - R3;           /* bytes left */
  57         P2 = R2;
  58
  59 .Ltoo_small:
  60         CC = P2 == 0;           /* Check zero count */
  61         IF CC JUMP .Lfinished;    /* Unusual */
  62
  63 .Lbytes:
  64         LSETUP (.Lbyte_loop , .Lbyte_loop) LC0=P2;
  65 .Lbyte_loop:
  66         B[P0++] = R1;
  67
  68 .Lfinished:
  69         RTS;
  70
  71 .Lforce_align:
  72         CC = BITTST (R0, 0);  /* odd byte */
  73         R0 = 4;
  74         R0 = R0 - R2;
  75         P1 = R0;
  76         R0 = P0;                    /* Recover return address */
  77         IF !CC JUMP .Lskip1;
  78         B[P0++] = R1;
  79 .Lskip1:
  80         CC = R2 <= 2;          /* 2 bytes */
  81         P2 -= P1;              /* reduce count */
  82         IF !CC JUMP .Laligned;
  83         B[P0++] = R1;
  84         B[P0++] = R1;
  85         JUMP .Laligned;
  86
  87 ENDPROC(_memset)