sysdeps/sparc/sparc64/strcmp.S

   1 /* Compare two strings for differences.
   2    For SPARC v9.
   3    Copyright (C) 2011-2013 Free Software Foundation, Inc.
   4    This file is part of the GNU C Library.
   5    Contributed by David S. Miller <davem@davemloft.net>
   6
   7    The GNU C Library is free software; you can redistribute it and/or
   8    modify it under the terms of the GNU Lesser General Public
   9    License as published by the Free Software Foundation; either
  10    version 2.1 of the License, or (at your option) any later version.
  11
  12    The GNU C Library is distributed in the hope that it will be useful,
  13    but WITHOUT ANY WARRANTY; without even the implied warranty of
  14    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  15    Lesser General Public License for more details.
  16
  17    You should have received a copy of the GNU Lesser General Public
  18    License along with the GNU C Library; if not, see
  19    <http://www.gnu.org/licenses/>.  */
  20
  21 #include <sysdep.h>
  22 #include <asm/asi.h>
  23
  24 #ifndef XCC
  25         .register       %g2, #scratch
  26         .register       %g3, #scratch
  27         .register       %g6, #scratch
  28 #endif
  29
  30 #define rSTR1           %o0
  31 #define rSTR2           %o1
  32 #define r0101           %o2     /* 0x0101010101010101 */
  33 #define r8080           %o3     /* 0x8080808080808080 */
  34 #define rSTRXOR         %o4
  35 #define rWORD1          %o5
  36 #define rTMP1           %g1
  37 #define rTMP2           %g2
  38 #define rWORD2          %g3
  39 #define rSLL            %g4
  40 #define rSRL            %g5
  41 #define rBARREL         %g6
  42
  43         /* There are two cases, either the two pointers are aligned
  44          * identically or they are not.  If they have the same
  45          * alignment we can use the normal full speed loop.  Otherwise
  46          * we have to use the barrel-shifter version.
  47          */
  48
  49         .text
  50         .align  32
  51 ENTRY(strcmp)
  52         or      rSTR2, rSTR1, rTMP1
  53         sethi   %hi(0x80808080), r8080
  54
  55         andcc   rTMP1, 0x7, %g0
  56         bne,pn  %icc, .Lmaybe_barrel_shift
  57          or     r8080, %lo(0x80808080), r8080
  58         ldx     [rSTR1], rWORD1
  59
  60         sub     rSTR2, rSTR1, rSTR2
  61         sllx    r8080, 32, rTMP1
  62
  63         ldx     [rSTR1 + rSTR2], rWORD2
  64         or      r8080, rTMP1, r8080
  65
  66         ba,pt   %xcc, .Laligned_loop_entry
  67          srlx   r8080, 7, r0101
  68
  69         .align  32
  70 .Laligned_loop_entry:
  71 .Laligned_loop:
  72         add     rSTR1, 8, rSTR1
  73
  74         sub     rWORD1, r0101, rTMP2
  75         xorcc   rWORD1, rWORD2, rSTRXOR
  76         bne,pn  %xcc, .Lcommon_endstring
  77
  78          andn   r8080, rWORD1, rTMP1
  79
  80         ldxa    [rSTR1] ASI_PNF, rWORD1
  81         andcc   rTMP1, rTMP2, %g0
  82         be,a,pt %xcc, .Laligned_loop
  83
  84          ldxa   [rSTR1 + rSTR2] ASI_PNF, rWORD2
  85
  86 .Lcommon_equal:
  87         retl
  88          mov    0, %o0
  89
  90         /* All loops terminate here once they find an unequal word.
  91          * If a zero byte appears in the word before the first unequal
  92          * byte, we must report zero.  Otherwise we report '1' or '-1'
  93          * depending upon whether the first mis-matching byte is larger
  94          * in the first string or the second, respectively.
  95          *
  96          * First we compute a 64-bit mask value that has "0x01" in
  97          * each byte where a zero exists in rWORD1.  rSTRXOR holds the
  98          * value (rWORD1 ^ rWORD2).  Therefore, if considered as an
  99          * unsigned quantity, our "0x01" mask value is "greater than"
 100          * rSTRXOR then a zero terminating byte comes first and
 101          * therefore we report '0'.
 102          *
 103          * The formula for this mask is:
 104          *
 105          *    mask_tmp1 = ~rWORD1 & 0x8080808080808080;
 106          *    mask_tmp2 = ((rWORD1 & 0x7f7f7f7f7f7f7f7f) +
 107          *                 0x7f7f7f7f7f7f7f7f);
 108          *
 109          *    mask = ((mask_tmp1 & ~mask_tmp2) >> 7);
 110          */
 111 .Lcommon_endstring:
 112         andn    rWORD1, r8080, rTMP2
 113         or      r8080, 1, %o1
 114
 115         mov     1, %o0
 116         sub     rTMP2, %o1, rTMP2
 117
 118         cmp     rWORD1, rWORD2
 119         andn    rTMP1, rTMP2, rTMP1
 120
 121         movleu  %xcc, -1, %o0
 122         srlx    rTMP1, 7, rTMP1
 123
 124         cmp     rTMP1, rSTRXOR
 125         retl
 126          movgu  %xcc, 0, %o0
 127
 128 .Lmaybe_barrel_shift:
 129         sub     rSTR2, rSTR1, rSTR2
 130         sllx    r8080, 32, rTMP1
 131
 132         or      r8080, rTMP1, r8080
 133         and     rSTR1, 0x7, rTMP2
 134
 135         srlx    r8080, 7, r0101
 136         andn    rSTR1, 0x7, rSTR1
 137
 138         ldxa    [rSTR1] ASI_PNF, rWORD1
 139         andcc   rSTR2, 0x7, rSLL
 140         sll     rTMP2, 3, rSTRXOR
 141
 142         bne,pn  %icc, .Lneed_barrel_shift
 143          mov    -1, rTMP1
 144         ldxa    [rSTR1 + rSTR2] ASI_PNF, rBARREL
 145
 146         srlx    rTMP1, rSTRXOR, rTMP2
 147
 148         orn     rWORD1, rTMP2, rWORD1
 149         ba,pt   %xcc, .Laligned_loop_entry
 150          orn    rBARREL, rTMP2, rWORD2
 151
 152 .Lneed_barrel_shift:
 153         sllx    rSLL, 3, rSLL
 154         andn    rSTR2, 0x7, rSTR2
 155
 156         ldxa    [rSTR1 + rSTR2] ASI_PNF, rBARREL
 157         mov     64, rTMP2
 158         sub     rTMP2, rSLL, rSRL
 159
 160         srlx    rTMP1, rSTRXOR, rTMP1
 161         add     rSTR2, 8, rSTR2
 162
 163         orn     rWORD1, rTMP1, rWORD1
 164         sllx    rBARREL, rSLL, rWORD2
 165         ldxa    [rSTR1 + rSTR2] ASI_PNF, rBARREL
 166
 167         add     rSTR1, 8, rSTR1
 168         sub     rWORD1, r0101, rTMP2
 169
 170         srlx    rBARREL, rSRL, rSTRXOR
 171
 172         or      rWORD2, rSTRXOR, rWORD2
 173
 174         orn     rWORD2, rTMP1, rWORD2
 175         ba,pt   %xcc, .Lbarrel_shift_loop_entry
 176          andn   r8080, rWORD1, rTMP1
 177
 178 .Lbarrel_shift_loop:
 179         sllx    rBARREL, rSLL, rWORD2
 180         ldxa    [rSTR1 + rSTR2] ASI_PNF, rBARREL
 181
 182         add     rSTR1, 8, rSTR1
 183         sub     rWORD1, r0101, rTMP2
 184
 185         srlx    rBARREL, rSRL, rSTRXOR
 186         andn    r8080, rWORD1, rTMP1
 187
 188         or      rWORD2, rSTRXOR, rWORD2
 189
 190 .Lbarrel_shift_loop_entry:
 191         xorcc   rWORD1, rWORD2, rSTRXOR
 192         bne,pn  %xcc, .Lcommon_endstring
 193
 194          andcc  rTMP1, rTMP2, %g0
 195         be,a,pt %xcc, .Lbarrel_shift_loop
 196          ldxa   [rSTR1] ASI_PNF, rWORD1
 197
 198         retl
 199          mov    0, %o0
 200 END(strcmp)
 201 libc_hidden_builtin_def (strcmp)