arch/hexagon/mm/strnlen_user.S

   1 /*
   2  * User string length functions for kernel
   3  *
   4  * Copyright (c) 2010-2011, The Linux Foundation. All rights reserved.
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License version 2 and
   8  * only version 2 as published by the Free Software Foundation.
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13  * GNU General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License
  16  * along with this program; if not, write to the Free Software
  17  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
  18  * 02110-1301, USA.
  19  */
  20
  21 #define isrc    r0
  22 #define max     r1      /*  Do not change!  */
  23
  24 #define end     r2
  25 #define tmp1    r3
  26
  27 #define obo     r6      /*  off-by-one  */
  28 #define start   r7
  29 #define mod8    r8
  30 #define dbuf    r15:14
  31 #define dcmp    r13:12
  32
  33 /*
  34  * The vector mask version of this turned out *really* badly.
  35  * The hardware loop version also turned out *really* badly.
  36  * Seems straight pointer arithmetic basically wins here.
  37  */
  38
  39 #define fname __strnlen_user
  40
  41         .text
  42         .global fname
  43         .type fname, @function
  44         .p2align 5  /*  why?  */
  45 fname:
  46         {
  47                 mod8 = and(isrc,#7);
  48                 end = add(isrc,max);
  49                 start = isrc;
  50         }
  51         {
  52                 P0 = cmp.eq(mod8,#0);
  53                 mod8 = and(end,#7);
  54                 dcmp = #0;
  55                 if (P0.new) jump:t dw_loop;     /*  fire up the oven  */
  56         }
  57
  58 alignment_loop:
  59 fail_1: {
  60                 tmp1 = memb(start++#1);
  61         }
  62         {
  63                 P0 = cmp.eq(tmp1,#0);
  64                 if (P0.new) jump:nt exit_found;
  65                 P1 = cmp.gtu(end,start);
  66                 mod8 = and(start,#7);
  67         }
  68         {
  69                 if (!P1) jump exit_error;  /*  hit the end  */
  70                 P0 = cmp.eq(mod8,#0);
  71         }
  72         {
  73                 if (!P0) jump alignment_loop;
  74         }
  75
  76
  77
  78 dw_loop:
  79 fail_2: {
  80                 dbuf = memd(start);
  81                 obo = add(start,#1);
  82         }
  83         {
  84                 P0 = vcmpb.eq(dbuf,dcmp);
  85         }
  86         {
  87                 tmp1 = P0;
  88                 P0 = cmp.gtu(end,start);
  89         }
  90         {
  91                 tmp1 = ct0(tmp1);
  92                 mod8 = and(end,#7);
  93                 if (!P0) jump end_check;
  94         }
  95         {
  96                 P0 = cmp.eq(tmp1,#32);
  97                 if (!P0.new) jump:nt exit_found;
  98                 if (!P0.new) start = add(obo,tmp1);
  99         }
 100         {
 101                 start = add(start,#8);
 102                 jump dw_loop;
 103         }       /*  might be nice to combine these jumps...   */
 104
 105
 106 end_check:
 107         {
 108                 P0 = cmp.gt(tmp1,mod8);
 109                 if (P0.new) jump:nt exit_error; /*  neverfound!  */
 110                 start = add(obo,tmp1);
 111         }
 112
 113 exit_found:
 114         {
 115                 R0 = sub(start,isrc);
 116                 jumpr R31;
 117         }
 118
 119 exit_error:
 120         {
 121                 R0 = add(max,#1);
 122                 jumpr R31;
 123         }
 124
 125         /*  Uh, what does the "fixup" return here?  */
 126         .falign
 127 fix_1:
 128         {
 129                 R0 = #0;
 130                 jumpr R31;
 131         }
 132
 133         .size fname,.-fname
 134
 135
 136 .section __ex_table,"a"
 137 .long fail_1,fix_1
 138 .long fail_2,fix_1
 139 .previous