sysdeps/x86_64/strtok.S

   1 /* strtok (str, delim) -- Return next DELIM separated token from STR.
   2    For AMD x86-64.
   3    Copyright (C) 1998,2000,2001,2002,2003 Free Software Foundation, Inc.
   4    This file is part of the GNU C Library.
   5    Based on i686 version contributed by Ulrich Drepper
   6    <drepper@cygnus.com>, 1998.
   7
   8    The GNU C Library is free software; you can redistribute it and/or
   9    modify it under the terms of the GNU Lesser General Public
  10    License as published by the Free Software Foundation; either
  11    version 2.1 of the License, or (at your option) any later version.
  12
  13    The GNU C Library is distributed in the hope that it will be useful,
  14    but WITHOUT ANY WARRANTY; without even the implied warranty of
  15    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  16    Lesser General Public License for more details.
  17
  18    You should have received a copy of the GNU Lesser General Public
  19    License along with the GNU C Library; if not, write to the Free
  20    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  21    02111-1307 USA.  */
  22
  23 #include <sysdep.h>
  24 #include "asm-syntax.h"
  25 #include "bp-sym.h"
  26 #include "bp-asm.h"
  27
  28 /* This file can be used for the strtok and strtok_r functions:
  29
  30    strtok:
  31         INPUT PARAMETER:
  32         str             %rdi
  33         delim           %rsi
  34
  35    strtok_r:
  36         INPUT PARAMETER:
  37         str             %rdi
  38         delim           %rsi
  39         save_ptr        %rdx
  40
  41    We do a common implementation here.  */
  42
  43 #ifdef USE_AS_STRTOK_R
  44 # define SAVE_PTR (%r9)
  45 #else
  46         .bss
  47         .local save_ptr
  48         ASM_TYPE_DIRECTIVE (save_ptr, @object)
  49         .size save_ptr, 8
  50 save_ptr:
  51         .space 8
  52
  53 # ifdef PIC
  54 #  define SAVE_PTR save_ptr(%rip)
  55 # else
  56 #  define SAVE_PTR save_ptr
  57 # endif
  58
  59 # define FUNCTION strtok
  60 #endif
  61
  62         .text
  63 ENTRY (BP_SYM (FUNCTION))
  64         /* First we create a table with flags for all possible characters.
  65            For the ASCII (7bit/8bit) or ISO-8859-X character sets which are
  66            supported by the C string functions we have 256 characters.
  67            Before inserting marks for the stop characters we clear the whole
  68            table.  */
  69         movq %rdi, %r8                  /* Save value.  */
  70         subq $256, %rsp                 /* Make space for 256 bytes.  */
  71         cfi_adjust_cfa_offset(256)
  72         movq $32,  %rcx                 /* 32*8 bytes = 256 bytes.  */
  73         movq %rsp, %rdi
  74         xorq %rax, %rax                 /* We store 0s.  */
  75         cld
  76         rep
  77         stosq
  78
  79         /* Note: %rcx = 0 !!! */
  80
  81 #ifdef USE_AS_STRTOK_R
  82         /* The value is stored in the third argument.  */
  83         movq %rdx, %rax
  84         movq %rdx, %r9          /* Save value - see def. of SAVE_PTR.  */
  85         movq (%rax), %rax
  86 #else
  87         /* The value is in the local variable defined above.  But
  88            we have to take care for PIC code.  */
  89         movq SAVE_PTR, %rax
  90 #endif
  91         movq %r8, %rdx          /* Get start of string.  */
  92
  93         /* If the pointer is NULL we have to use the stored value of
  94            the last run.  */
  95         cmpq $0, %rdx
  96         cmove %rax, %rdx
  97         testq %rdx, %rdx
  98         jz L(returnNULL)
  99         movq %rsi, %rax         /* Get start of delimiter set.  */
 100
 101 /* For understanding the following code remember that %rcx == 0 now.
 102    Although all the following instruction only modify %cl we always
 103    have a correct zero-extended 64-bit value in %rcx.  */
 104
 105 L(2):   movb (%rax), %cl        /* get byte from stopset */
 106         testb %cl, %cl          /* is NUL char? */
 107         jz L(1)                 /* yes => start compare loop */
 108         movb %cl, (%rsp,%rcx)   /* set corresponding byte in stopset table */
 109
 110         movb 1(%rax), %cl       /* get byte from stopset */
 111         testb $0xff, %cl        /* is NUL char? */
 112         jz L(1)                 /* yes => start compare loop */
 113         movb %cl, (%rsp,%rcx)   /* set corresponding byte in stopset table */
 114
 115         movb 2(%rax), %cl       /* get byte from stopset */
 116         testb $0xff, %cl        /* is NUL char? */
 117         jz L(1)                 /* yes => start compare loop */
 118         movb %cl, (%rsp,%rcx)   /* set corresponding byte in stopset table */
 119
 120         movb 3(%rax), %cl       /* get byte from stopset */
 121         addq $4, %rax           /* increment stopset pointer */
 122         movb %cl, (%rsp,%rcx)   /* set corresponding byte in stopset table */
 123         testb $0xff, %cl        /* is NUL char? */
 124         jnz L(2)                /* no => process next dword from stopset */
 125
 126 L(1):
 127
 128         leaq -4(%rdx), %rax     /* prepare loop */
 129
 130         /* We use a neat trick for the following loop.  Normally we would
 131            have to test for two termination conditions
 132            1. a character in the stopset was found
 133            and
 134            2. the end of the string was found
 135            As a sign that the character is in the stopset we store its
 136            value in the table.  The value of NUL is NUL so the loop
 137            terminates for NUL in every case.  */
 138
 139 L(3):   addq $4, %rax           /* adjust pointer for full loop round */
 140
 141         movb (%rax), %cl        /* get byte from string */
 142         testb %cl, (%rsp,%rcx)  /* is it contained in stopset? */
 143         jz L(4)                 /* no => start of token */
 144
 145         movb 1(%rax), %cl       /* get byte from string */
 146         testb %cl, (%rsp,%rcx)  /* is it contained in stopset? */
 147         jz L(5)                 /* no => start of token */
 148
 149         movb 2(%rax), %cl       /* get byte from string */
 150         testb %cl, (%rsp,%rcx)  /* is it contained in stopset? */
 151         jz L(6)                 /* no => start of token */
 152
 153         movb 3(%rax), %cl       /* get byte from string */
 154         testb %cl, (%rsp,%rcx)  /* is it contained in stopset? */
 155         jnz L(3)                /* yes => start of loop */
 156
 157         incq %rax               /* adjust pointer */
 158 L(6):   incq %rax
 159 L(5):   incq %rax
 160
 161         /* Now we have to terminate the string.  */
 162
 163 L(4):   leaq -4(%rax), %rdx     /* We use %rDX for the next run.  */
 164
 165 L(7):   addq $4, %rdx           /* adjust pointer for full loop round */
 166
 167         movb (%rdx), %cl        /* get byte from string */
 168         cmpb %cl, (%rsp,%rcx)   /* is it contained in skipset? */
 169         je L(8)                 /* yes => return */
 170
 171         movb 1(%rdx), %cl       /* get byte from string */
 172         cmpb %cl, (%rsp,%rcx)   /* is it contained in skipset? */
 173         je L(9)                 /* yes => return */
 174
 175         movb 2(%rdx), %cl       /* get byte from string */
 176         cmpb %cl, (%rsp,%rcx)   /* is it contained in skipset? */
 177         je L(10)                /* yes => return */
 178
 179         movb 3(%rdx), %cl       /* get byte from string */
 180         cmpb %cl, (%rsp,%rcx)   /* is it contained in skipset? */
 181         jne L(7)                /* no => start loop again */
 182
 183         incq %rdx               /* adjust pointer */
 184 L(10):  incq %rdx
 185 L(9):   incq %rdx
 186
 187 L(8):   cmpq %rax, %rdx
 188         je L(returnNULL)        /* There was no token anymore.  */
 189
 190         movb $0, (%rdx)         /* Terminate string.  */
 191
 192         /* Are we at end of string?  */
 193         cmpb $0, %cl
 194         leaq 1(%rdx), %rcx
 195         cmovne %rcx, %rdx
 196
 197         /* Store the pointer to the next character.  */
 198         movq %rdx, SAVE_PTR
 199
 200 L(epilogue):
 201         /* Remove the stopset table.  */
 202         addq $256, %rsp
 203         cfi_adjust_cfa_offset(-256)
 204         retq
 205
 206 L(returnNULL):
 207         xorq %rax, %rax
 208         jmp L(epilogue)
 209
 210 END (BP_SYM (FUNCTION))