arch/sparc/lib/strlen.S

   1 /* strlen.S: Sparc optimized strlen code
   2  * Hand optimized from GNU libc's strlen
   3  * Copyright (C) 1991,1996 Free Software Foundation
   4  * Copyright (C) 1996,2008 David S. Miller (davem@davemloft.net)
   5  * Copyright (C) 1996, 1997 Jakub Jelinek (jj@sunsite.mff.cuni.cz)
   6  */
   7
   8 #include <linux/linkage.h>
   9 #include <asm/asm.h>
  10
  11 #define LO_MAGIC 0x01010101
  12 #define HI_MAGIC 0x80808080
  13
  14         .text
  15 ENTRY(strlen)
  16         mov     %o0, %o1
  17         andcc   %o0, 3, %g0
  18         BRANCH32(be, pt, 9f)
  19          sethi  %hi(HI_MAGIC), %o4
  20         ldub    [%o0], %o5
  21         BRANCH_REG_ZERO(pn, %o5, 11f)
  22          add    %o0, 1, %o0
  23         andcc   %o0, 3, %g0
  24         BRANCH32(be, pn, 4f)
  25          or     %o4, %lo(HI_MAGIC), %o3
  26         ldub    [%o0], %o5
  27         BRANCH_REG_ZERO(pn, %o5, 12f)
  28          add    %o0, 1, %o0
  29         andcc   %o0, 3, %g0
  30         BRANCH32(be, pt, 5f)
  31          sethi  %hi(LO_MAGIC), %o4
  32         ldub    [%o0], %o5
  33         BRANCH_REG_ZERO(pn, %o5, 13f)
  34          add    %o0, 1, %o0
  35         BRANCH32(ba, pt, 8f)
  36          or     %o4, %lo(LO_MAGIC), %o2
  37 9:
  38         or      %o4, %lo(HI_MAGIC), %o3
  39 4:
  40         sethi   %hi(LO_MAGIC), %o4
  41 5:
  42         or      %o4, %lo(LO_MAGIC), %o2
  43 8:
  44         ld      [%o0], %o5
  45 2:
  46         sub     %o5, %o2, %o4
  47         andcc   %o4, %o3, %g0
  48         BRANCH32(be, pt, 8b)
  49          add    %o0, 4, %o0
  50
  51         /* Check every byte. */
  52         srl     %o5, 24, %g7
  53         andcc   %g7, 0xff, %g0
  54         BRANCH32(be, pn, 1f)
  55          add    %o0, -4, %o4
  56         srl     %o5, 16, %g7
  57         andcc   %g7, 0xff, %g0
  58         BRANCH32(be, pn, 1f)
  59          add    %o4, 1, %o4
  60         srl     %o5, 8, %g7
  61         andcc   %g7, 0xff, %g0
  62         BRANCH32(be, pn, 1f)
  63          add    %o4, 1, %o4
  64         andcc   %o5, 0xff, %g0
  65         BRANCH32_ANNUL(bne, pt, 2b)
  66          ld     [%o0], %o5
  67         add     %o4, 1, %o4
  68 1:
  69         retl
  70          sub    %o4, %o1, %o0
  71 11:
  72         retl
  73          mov    0, %o0
  74 12:
  75         retl
  76          mov    1, %o0
  77 13:
  78         retl
  79          mov    2, %o0
  80 ENDPROC(strlen)