Sireesh Tripurari | b478e66 | 2014-05-09 15:15:10 +0530 | [diff] [blame^] | 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> |
| 23 | |
| 24 | static int |
| 25 | png_have_neon(png_structp png_ptr) |
| 26 | { |
| 27 | FILE *f = fopen("/proc/cpuinfo", "rb"); |
| 28 | |
| 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 }; |
| 36 | |
| 37 | enum |
| 38 | { |
| 39 | StartLine, Feature, Colon, StartTag, Neon, HaveNeon, SkipTag, SkipLine |
| 40 | } state; |
| 41 | int counter; |
| 42 | |
| 43 | for (state=StartLine, counter=0;;) |
| 44 | { |
| 45 | int ch = fgetc(f); |
| 46 | |
| 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 | } |
| 55 | |
| 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; |
| 62 | |
| 63 | counter=0; |
| 64 | state = Feature; |
| 65 | /* FALL THROUGH */ |
| 66 | |
| 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 | } |
| 75 | |
| 76 | /* did not match 'feature' */ |
| 77 | state = SkipLine; |
| 78 | /* FALL THROUGH */ |
| 79 | |
| 80 | case SkipLine: |
| 81 | skipLine: |
| 82 | /* Skip everything until we see linefeed or carriage return */ |
| 83 | if (ch != 10 && ch != 13) |
| 84 | break; |
| 85 | |
| 86 | state = StartLine; |
| 87 | break; |
| 88 | |
| 89 | case Colon: |
| 90 | /* Match any number of space or tab followed by ':' */ |
| 91 | if (ch == 32 || ch == 9) |
| 92 | break; |
| 93 | |
| 94 | if (ch == 58) /* i.e. ':' */ |
| 95 | { |
| 96 | state = StartTag; |
| 97 | break; |
| 98 | } |
| 99 | |
| 100 | /* Either a bad line format or a 'feature' prefix followed by |
| 101 | * other characters. |
| 102 | */ |
| 103 | state = SkipLine; |
| 104 | goto skipLine; |
| 105 | |
| 106 | case StartTag: |
| 107 | /* Skip space characters before a tag */ |
| 108 | if (ch == 32 || ch == 9) |
| 109 | break; |
| 110 | |
| 111 | state = Neon; |
| 112 | counter = 0; |
| 113 | /* FALL THROUGH */ |
| 114 | |
| 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 | } |
| 123 | |
| 124 | state = SkipTag; |
| 125 | /* FALL THROUGH */ |
| 126 | |
| 127 | case SkipTag: |
| 128 | /* Skip non-space characters */ |
| 129 | if (ch == 10 || ch == 13) |
| 130 | state = StartLine; |
| 131 | |
| 132 | else if (ch == 32 || ch == 9) |
| 133 | state = StartTag; |
| 134 | break; |
| 135 | |
| 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 | } |
| 145 | |
| 146 | state = SkipTag; |
| 147 | break; |
| 148 | |
| 149 | default: |
| 150 | png_error(png_ptr, "png_have_neon: internal error (bug)"); |
| 151 | } |
| 152 | } |
| 153 | } |
| 154 | |
| 155 | else |
| 156 | png_warning(png_ptr, "/proc/cpuinfo open failed"); |
| 157 | |
| 158 | return 0; |
| 159 | } |