The Tor Browser: media/libpng/arm/linux.c@6474c204b198

Cloned upstream origin tor-browser at tor-browser-31.3.0esr-4.5-1-build1
revision ID fc1c9ff7c1b2defdbc039f12214767608f46423f for hacking purpose.

     1 /* contrib/arm-neon/linux.c

     2  *

     3  * Copyright (c) 2014 Glenn Randers-Pehrson

     4  * Written by John Bowler, 2014.

     5  * Last changed in libpng 1.6.10 [March 6, 2014]

     6  *

     7  * This code is released under the libpng license.

     8  * For conditions of distribution and use, see the disclaimer

     9  * and license in png.h

    10  *

    11  * SEE contrib/arm-neon/README before reporting bugs

    12  *

    13  * STATUS: SUPPORTED

    14  * BUG REPORTS: png-mng-implement@sourceforge.net

    15  *

    16  * png_have_neon implemented for Linux by reading the widely available

    17  * pseudo-file /proc/cpuinfo.

    18  *

    19  * This code is strict ANSI-C and is probably moderately portable, it does

    20  * however use <stdio.h> and assumes that /proc/cpuinfo is never localized.

    21  */

    22 #include <stdio.h>

    24 static int

    25 png_have_neon(png_structp png_ptr)

    26 {

    27    FILE *f = fopen("/proc/cpuinfo", "rb");

    29    if (f != NULL)

    30    {

    31       /* This is a simple state machine which reads the input byte-by-byte until

    32        * it gets a match on the 'neon' feature or reaches the end of the stream.

    33        */

    34       static const char ch_feature[] = { 70, 69, 65, 84, 85, 82, 69, 83 };

    35       static const char ch_neon[] = { 78, 69, 79, 78 };

    37       enum

    38       {

    39          StartLine, Feature, Colon, StartTag, Neon, HaveNeon, SkipTag, SkipLine

    40       }  state;

    41       int counter;

    43       for (state=StartLine, counter=0;;)

    44       {

    45          int ch = fgetc(f);

    47          if (ch == EOF)

    48          {

    49             /* EOF means error or end-of-file, return false; neon at EOF is

    50              * assumed to be a mistake.

    51              */

    52             fclose(f);

    53             return 0;

    54          }

    56          switch (state)

    57          {

    58             case StartLine:

    59                /* Match spaces at the start of line */

    60                if (ch <= 32) /* skip control characters and space */

    61                   break;

    63                counter=0;

    64                state = Feature;

    65                /* FALL THROUGH */

    67             case Feature:

    68                /* Match 'FEATURE', ASCII case insensitive. */

    69                if ((ch & ~0x20) == ch_feature[counter])

    70                {

    71                   if (++counter == (sizeof ch_feature))

    72                      state = Colon;

    73                   break;

    74                }

    76                /* did not match 'feature' */

    77                state = SkipLine;

    78                /* FALL THROUGH */

    80             case SkipLine:

    81             skipLine:

    82                /* Skip everything until we see linefeed or carriage return */

    83                if (ch != 10 && ch != 13)

    84                   break;

    86                state = StartLine;

    87                break;

    89             case Colon:

    90                /* Match any number of space or tab followed by ':' */

    91                if (ch == 32 || ch == 9)

    92                   break;

    94                if (ch == 58) /* i.e. ':' */

    95                {

    96                   state = StartTag;

    97                   break;

    98                }

   100                /* Either a bad line format or a 'feature' prefix followed by

   101                 * other characters.

   102                 */

   103                state = SkipLine;

   104                goto skipLine;

   106             case StartTag:

   107                /* Skip space characters before a tag */

   108                if (ch == 32 || ch == 9)

   109                   break;

   111                state = Neon;

   112                counter = 0;

   113                /* FALL THROUGH */

   115             case Neon:

   116                /* Look for 'neon' tag */

   117                if ((ch & ~0x20) == ch_neon[counter])

   118                {

   119                   if (++counter == (sizeof ch_neon))

   120                      state = HaveNeon;

   121                   break;

   122                }

   124                state = SkipTag;

   125                /* FALL THROUGH */

   127             case SkipTag:

   128                /* Skip non-space characters */

   129                if (ch == 10 || ch == 13)

   130                   state = StartLine;

   132                else if (ch == 32 || ch == 9)

   133                   state = StartTag;

   134                break;

   136             case HaveNeon:

   137                /* Have seen a 'neon' prefix, but there must be a space or new

   138                 * line character to terminate it.

   139                 */

   140                if (ch == 10 || ch == 13 || ch == 32 || ch == 9)

   141                {

   142                   fclose(f);

   143                   return 1;

   144                }

   146                state = SkipTag;

   147                break;

   149             default:

   150                png_error(png_ptr, "png_have_neon: internal error (bug)");

   151          }

   152       }

   153    }

   155    else

   156       png_warning(png_ptr, "/proc/cpuinfo open failed");

   158    return 0;

   159 }

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