arch/arc/lib/strchr-700.S

   1 /*
   2  * Copyright (C) 2004, 2007-2010, 2011-2014 Synopsys, Inc. All rights reserved.
   3  *
   4  * SPDX-License-Identifier:     GPL-2.0+
   5  */
   6
   7 /*
   8  * ARC700 has a relatively long pipeline and branch prediction, so we want
   9  * to avoid branches that are hard to predict.  On the other hand, the
  10  * presence of the norm instruction makes it easier to operate on whole
  11  * words branch-free.
  12  */
  13
  14 .global strchr
  15 .align 4
  16 strchr:
  17         extb_s  %r1, %r1
  18         asl     %r5, %r1, 8
  19         bmsk    %r2, %r0, 1
  20         or      %r5, %r5, %r1
  21         mov_s   %r3, 0x01010101
  22         breq.d  %r2, %r0, .Laligned
  23         asl     %r4, %r5, 16
  24         sub_s   %r0, %r0, %r2
  25         asl     %r7, %r2, 3
  26         ld_s    %r2, [%r0]
  27 #ifdef __LITTLE_ENDIAN__
  28         asl     %r7, %r3, %r7
  29 #else /* __BIG_ENDIAN__ */
  30         lsr     %r7, %r3, %r7
  31 #endif /* _ENDIAN__ */
  32         or      %r5, %r5, %r4
  33         ror     %r4, %r3
  34         sub     %r12, %r2, %r7
  35         bic_s   %r12, %r12, %r2
  36         and     %r12, %r12, %r4
  37         brne.d  %r12, 0, .Lfound0_ua
  38         xor     %r6, %r2, %r5
  39         ld.a    %r2, [%r0, 4]
  40         sub     %r12, %r6, %r7
  41         bic     %r12, %r12, %r6
  42 #ifdef __LITTLE_ENDIAN__
  43         and     %r7, %r12, %r4
  44         /* For speed, we want this branch to be unaligned. */
  45         breq    %r7, 0, .Loop
  46         /* Likewise this one */
  47         b       .Lfound_char
  48 #else /* __BIG_ENDIAN__ */
  49         and     %r12, %r12, %r4
  50         /* For speed, we want this branch to be unaligned. */
  51         breq    %r12, 0, .Loop
  52         lsr_s   %r12, %r12, 7
  53         bic     %r2, %r7, %r6
  54         b.d     .Lfound_char_b
  55         and_s   %r2, %r2, %r12
  56 #endif /* _ENDIAN__ */
  57         /* We require this code address to be unaligned for speed...  */
  58 .Laligned:
  59         ld_s    %r2, [%r0]
  60         or      %r5, %r5, %r4
  61         ror     %r4, %r3
  62         /* ... so that this code address is aligned, for itself and ...  */
  63 .Loop:
  64         sub     %r12, %r2, %r3
  65         bic_s   %r12, %r12, %r2
  66         and     %r12, %r12, %r4
  67         brne.d  %r12, 0, .Lfound0
  68         xor     %r6, %r2, %r5
  69         ld.a    %r2, [%r0, 4]
  70         sub     %r12, %r6, %r3
  71         bic     %r12, %r12, %r6
  72         and     %r7, %r12, %r4
  73         breq    %r7, 0, .Loop
  74         /*
  75          *... so that this branch is unaligned.
  76          * Found searched-for character.
  77          * r0 has already advanced to next word.
  78          */
  79 #ifdef __LITTLE_ENDIAN__
  80         /*
  81          * We only need the information about the first matching byte
  82          * (i.e. the least significant matching byte) to be exact,
  83          * hence there is no problem with carry effects.
  84          */
  85 .Lfound_char:
  86         sub     %r3, %r7, 1
  87         bic     %r3, %r3, %r7
  88         norm    %r2, %r3
  89         sub_s   %r0, %r0, 1
  90         asr_s   %r2, %r2, 3
  91         j.d     [%blink]
  92         sub_s   %r0, %r0, %r2
  93
  94         .balign 4
  95 .Lfound0_ua:
  96         mov     %r3, %r7
  97 .Lfound0:
  98         sub     %r3, %r6, %r3
  99         bic     %r3, %r3, %r6
 100         and     %r2, %r3, %r4
 101         or_s    %r12, %r12, %r2
 102         sub_s   %r3, %r12, 1
 103         bic_s   %r3, %r3, %r12
 104         norm    %r3, %r3
 105         add_s   %r0, %r0, 3
 106         asr_s   %r12, %r3, 3
 107         asl.f   0, %r2, %r3
 108         sub_s   %r0, %r0, %r12
 109         j_s.d   [%blink]
 110         mov.pl  %r0, 0
 111 #else /* __BIG_ENDIAN__ */
 112 .Lfound_char:
 113         lsr     %r7, %r7, 7
 114
 115         bic     %r2, %r7, %r6
 116 .Lfound_char_b:
 117         norm    %r2, %r2
 118         sub_s   %r0, %r0, 4
 119         asr_s   %r2, %r2, 3
 120         j.d     [%blink]
 121         add_s   %r0, %r0, %r2
 122
 123 .Lfound0_ua:
 124         mov_s   %r3, %r7
 125 .Lfound0:
 126         asl_s   %r2, %r2, 7
 127         or      %r7, %r6, %r4
 128         bic_s   %r12, %r12, %r2
 129         sub     %r2, %r7, %r3
 130         or      %r2, %r2, %r6
 131         bic     %r12, %r2, %r12
 132         bic.f   %r3, %r4, %r12
 133         norm    %r3, %r3
 134
 135         add.pl  %r3, %r3, 1
 136         asr_s   %r12, %r3, 3
 137         asl.f   0, %r2, %r3
 138         add_s   %r0, %r0, %r12
 139         j_s.d   [%blink]
 140         mov.mi  %r0, 0
 141 #endif /* _ENDIAN__ */