arch/metag/lib/memset.S

   1 !   Copyright (C) 2008-2012 Imagination Technologies Ltd.
   2
   3         .text
   4         .global _memset
   5         .type   _memset,function
   6 ! D1Ar1 dst
   7 ! D0Ar2 c
   8 ! D1Ar3 cnt
   9 ! D0Re0 dst
  10 _memset:
  11         AND     D0Ar2,D0Ar2,#0xFF       ! Ensure a byte input value
  12         MULW    D0Ar2,D0Ar2,#0x0101     ! Duplicate byte value into  0-15
  13         ANDS    D0Ar4,D1Ar1,#7          ! Extract bottom LSBs of dst
  14         LSL     D0Re0,D0Ar2,#16         ! Duplicate byte value into 16-31
  15         ADD     A0.2,D0Ar2,D0Re0        ! Duplicate byte value into 4 (A0.2)
  16         MOV     D0Re0,D1Ar1             ! Return dst
  17         BZ      $LLongStub              ! if start address is aligned
  18         ! start address is not aligned on an 8 byte boundary, so we
  19         ! need the number of bytes up to the next 8 byte address
  20         ! boundary, or the length of the string if less than 8, in D1Ar5
  21         MOV     D0Ar2,#8                ! Need 8 - N in D1Ar5 ...
  22         SUB     D1Ar5,D0Ar2,D0Ar4       !            ... subtract N
  23         CMP     D1Ar3,D1Ar5
  24         MOVMI   D1Ar5,D1Ar3
  25         B       $LByteStub              ! dst is mis-aligned, do $LByteStub
  26
  27 !
  28 ! Preamble to LongLoop which generates 4*8 bytes per interation (5 cycles)
  29 !
  30 $LLongStub:
  31         LSRS    D0Ar2,D1Ar3,#5
  32         AND     D1Ar3,D1Ar3,#0x1F
  33         MOV     A1.2,A0.2
  34         BEQ     $LLongishStub
  35         SUB     TXRPT,D0Ar2,#1
  36         CMP     D1Ar3,#0
  37 $LLongLoop:
  38         SETL    [D1Ar1++],A0.2,A1.2
  39         SETL    [D1Ar1++],A0.2,A1.2
  40         SETL    [D1Ar1++],A0.2,A1.2
  41         SETL    [D1Ar1++],A0.2,A1.2
  42         BR      $LLongLoop
  43         BZ      $Lexit
  44 !
  45 ! Preamble to LongishLoop which generates 1*8 bytes per interation (2 cycles)
  46 !
  47 $LLongishStub:
  48         LSRS    D0Ar2,D1Ar3,#3
  49         AND     D1Ar3,D1Ar3,#0x7
  50         MOV     D1Ar5,D1Ar3
  51         BEQ     $LByteStub
  52         SUB     TXRPT,D0Ar2,#1
  53         CMP     D1Ar3,#0
  54 $LLongishLoop:
  55         SETL    [D1Ar1++],A0.2,A1.2
  56         BR      $LLongishLoop
  57         BZ      $Lexit
  58 !
  59 ! This does a byte structured burst of up to 7 bytes
  60 !
  61 !       D1Ar1 should point to the location required
  62 !       D1Ar3 should be the remaining total byte count
  63 !       D1Ar5 should be burst size (<= D1Ar3)
  64 !
  65 $LByteStub:
  66         SUBS    D1Ar3,D1Ar3,D1Ar5       ! Reduce count
  67         ADD     D1Ar1,D1Ar1,D1Ar5       ! Advance pointer to end of area
  68         MULW    D1Ar5,D1Ar5,#4          ! Scale to (1*4), (2*4), (3*4)
  69         SUB     D1Ar5,D1Ar5,#(8*4)      ! Rebase to -(7*4), -(6*4), -(5*4), ...
  70         MOV     A1.2,D1Ar5
  71         SUB     PC,CPC1,A1.2            ! Jump into table below
  72         SETB    [D1Ar1+#(-7)],A0.2
  73         SETB    [D1Ar1+#(-6)],A0.2
  74         SETB    [D1Ar1+#(-5)],A0.2
  75         SETB    [D1Ar1+#(-4)],A0.2
  76         SETB    [D1Ar1+#(-3)],A0.2
  77         SETB    [D1Ar1+#(-2)],A0.2
  78         SETB    [D1Ar1+#(-1)],A0.2
  79 !
  80 ! Return if all data has been output, otherwise do $LLongStub
  81 !
  82         BNZ     $LLongStub
  83 $Lexit:
  84         MOV     PC,D1RtP
  85         .size _memset,.-_memset
  86