root/arch/arc/lib/strchr-700.S

   1 /* SPDX-License-Identifier: GPL-2.0-only */
   2 /*
   3  * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
   4  */
   5 
   6 /* ARC700 has a relatively long pipeline and branch prediction, so we want
   7    to avoid branches that are hard to predict.  On the other hand, the
   8    presence of the norm instruction makes it easier to operate on whole
   9    words branch-free.  */
  10 
  11 #include <linux/linkage.h>
  12 
  13 ENTRY_CFI(strchr)
  14         extb_s  r1,r1
  15         asl     r5,r1,8
  16         bmsk    r2,r0,1
  17         or      r5,r5,r1
  18         mov_s   r3,0x01010101
  19         breq.d  r2,r0,.Laligned
  20         asl     r4,r5,16
  21         sub_s   r0,r0,r2
  22         asl     r7,r2,3
  23         ld_s    r2,[r0]
  24 #ifdef __LITTLE_ENDIAN__
  25         asl     r7,r3,r7
  26 #else
  27         lsr     r7,r3,r7
  28 #endif
  29         or      r5,r5,r4
  30         ror     r4,r3
  31         sub     r12,r2,r7
  32         bic_s   r12,r12,r2
  33         and     r12,r12,r4
  34         brne.d  r12,0,.Lfound0_ua
  35         xor     r6,r2,r5
  36         ld.a    r2,[r0,4]
  37         sub     r12,r6,r7
  38         bic     r12,r12,r6
  39 #ifdef __LITTLE_ENDIAN__
  40         and     r7,r12,r4
  41         breq    r7,0,.Loop ; For speed, we want this branch to be unaligned.
  42         b       .Lfound_char ; Likewise this one.
  43 #else
  44         and     r12,r12,r4
  45         breq    r12,0,.Loop ; For speed, we want this branch to be unaligned.
  46         lsr_s   r12,r12,7
  47         bic     r2,r7,r6
  48         b.d     .Lfound_char_b
  49         and_s   r2,r2,r12
  50 #endif
  51 ; /* We require this code address to be unaligned for speed...  */
  52 .Laligned:
  53         ld_s    r2,[r0]
  54         or      r5,r5,r4
  55         ror     r4,r3
  56 ; /* ... so that this code address is aligned, for itself and ...  */
  57 .Loop:
  58         sub     r12,r2,r3
  59         bic_s   r12,r12,r2
  60         and     r12,r12,r4
  61         brne.d  r12,0,.Lfound0
  62         xor     r6,r2,r5
  63         ld.a    r2,[r0,4]
  64         sub     r12,r6,r3
  65         bic     r12,r12,r6
  66         and     r7,r12,r4
  67         breq    r7,0,.Loop /* ... so that this branch is unaligned.  */
  68         ; Found searched-for character.  r0 has already advanced to next word.
  69 #ifdef __LITTLE_ENDIAN__
  70 /* We only need the information about the first matching byte
  71    (i.e. the least significant matching byte) to be exact,
  72    hence there is no problem with carry effects.  */
  73 .Lfound_char:
  74         sub     r3,r7,1
  75         bic     r3,r3,r7
  76         norm    r2,r3
  77         sub_s   r0,r0,1
  78         asr_s   r2,r2,3
  79         j.d     [blink]
  80         sub_s   r0,r0,r2
  81 
  82         .balign 4
  83 .Lfound0_ua:
  84         mov     r3,r7
  85 .Lfound0:
  86         sub     r3,r6,r3
  87         bic     r3,r3,r6
  88         and     r2,r3,r4
  89         or_s    r12,r12,r2
  90         sub_s   r3,r12,1
  91         bic_s   r3,r3,r12
  92         norm    r3,r3
  93         add_s   r0,r0,3
  94         asr_s   r12,r3,3
  95         asl.f   0,r2,r3
  96         sub_s   r0,r0,r12
  97         j_s.d   [blink]
  98         mov.pl  r0,0
  99 #else /* BIG ENDIAN */
 100 .Lfound_char:
 101         lsr     r7,r7,7
 102 
 103         bic     r2,r7,r6
 104 .Lfound_char_b:
 105         norm    r2,r2
 106         sub_s   r0,r0,4
 107         asr_s   r2,r2,3
 108         j.d     [blink]
 109         add_s   r0,r0,r2
 110 
 111 .Lfound0_ua:
 112         mov_s   r3,r7
 113 .Lfound0:
 114         asl_s   r2,r2,7
 115         or      r7,r6,r4
 116         bic_s   r12,r12,r2
 117         sub     r2,r7,r3
 118         or      r2,r2,r6
 119         bic     r12,r2,r12
 120         bic.f   r3,r4,r12
 121         norm    r3,r3
 122 
 123         add.pl  r3,r3,1
 124         asr_s   r12,r3,3
 125         asl.f   0,r2,r3
 126         add_s   r0,r0,r12
 127         j_s.d   [blink]
 128         mov.mi  r0,0
 129 #endif /* ENDIAN */
 130 END_CFI(strchr)