LXR linux/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
  87