| /* contrib/arm-neon/linux.c |
| * |
| * Copyright (c) 2014 Glenn Randers-Pehrson |
| * Written by John Bowler, 2014. |
| * Last changed in libpng 1.6.16 [December 22, 2014] |
| * |
| * This code is released under the libpng license. |
| * For conditions of distribution and use, see the disclaimer |
| * and license in png.h |
| * |
| * SEE contrib/arm-neon/README before reporting bugs |
| * |
| * STATUS: SUPPORTED |
| * BUG REPORTS: png-mng-implement@sourceforge.net |
| * |
| * png_have_neon implemented for Linux by reading the widely available |
| * pseudo-file /proc/cpuinfo. |
| * |
| * This code is strict ANSI-C and is probably moderately portable; it does |
| * however use <stdio.h> and it assumes that /proc/cpuinfo is never localized. |
| */ |
| #include <stdio.h> |
| |
| static int |
| png_have_neon(png_structp png_ptr) |
| { |
| FILE *f = fopen("/proc/cpuinfo", "rb"); |
| |
| if (f != NULL) |
| { |
| /* This is a simple state machine which reads the input byte-by-byte until |
| * it gets a match on the 'neon' feature or reaches the end of the stream. |
| */ |
| static const char ch_feature[] = { 70, 69, 65, 84, 85, 82, 69, 83 }; |
| static const char ch_neon[] = { 78, 69, 79, 78 }; |
| |
| enum |
| { |
| StartLine, Feature, Colon, StartTag, Neon, HaveNeon, SkipTag, SkipLine |
| } state; |
| int counter; |
| |
| for (state=StartLine, counter=0;;) |
| { |
| int ch = fgetc(f); |
| |
| if (ch == EOF) |
| { |
| /* EOF means error or end-of-file, return false; neon at EOF is |
| * assumed to be a mistake. |
| */ |
| fclose(f); |
| return 0; |
| } |
| |
| switch (state) |
| { |
| case StartLine: |
| /* Match spaces at the start of line */ |
| if (ch <= 32) /* skip control characters and space */ |
| break; |
| |
| counter=0; |
| state = Feature; |
| /* FALL THROUGH */ |
| |
| case Feature: |
| /* Match 'FEATURE', ASCII case insensitive. */ |
| if ((ch & ~0x20) == ch_feature[counter]) |
| { |
| if (++counter == (sizeof ch_feature)) |
| state = Colon; |
| break; |
| } |
| |
| /* did not match 'feature' */ |
| state = SkipLine; |
| /* FALL THROUGH */ |
| |
| case SkipLine: |
| skipLine: |
| /* Skip everything until we see linefeed or carriage return */ |
| if (ch != 10 && ch != 13) |
| break; |
| |
| state = StartLine; |
| break; |
| |
| case Colon: |
| /* Match any number of space or tab followed by ':' */ |
| if (ch == 32 || ch == 9) |
| break; |
| |
| if (ch == 58) /* i.e. ':' */ |
| { |
| state = StartTag; |
| break; |
| } |
| |
| /* Either a bad line format or a 'feature' prefix followed by |
| * other characters. |
| */ |
| state = SkipLine; |
| goto skipLine; |
| |
| case StartTag: |
| /* Skip space characters before a tag */ |
| if (ch == 32 || ch == 9) |
| break; |
| |
| state = Neon; |
| counter = 0; |
| /* FALL THROUGH */ |
| |
| case Neon: |
| /* Look for 'neon' tag */ |
| if ((ch & ~0x20) == ch_neon[counter]) |
| { |
| if (++counter == (sizeof ch_neon)) |
| state = HaveNeon; |
| break; |
| } |
| |
| state = SkipTag; |
| /* FALL THROUGH */ |
| |
| case SkipTag: |
| /* Skip non-space characters */ |
| if (ch == 10 || ch == 13) |
| state = StartLine; |
| |
| else if (ch == 32 || ch == 9) |
| state = StartTag; |
| break; |
| |
| case HaveNeon: |
| /* Have seen a 'neon' prefix, but there must be a space or new |
| * line character to terminate it. |
| */ |
| if (ch == 10 || ch == 13 || ch == 32 || ch == 9) |
| { |
| fclose(f); |
| return 1; |
| } |
| |
| state = SkipTag; |
| break; |
| |
| default: |
| png_error(png_ptr, "png_have_neon: internal error (bug)"); |
| } |
| } |
| } |
| |
| #ifdef PNG_WARNINGS_SUPPORTED |
| else |
| png_warning(png_ptr, "/proc/cpuinfo open failed"); |
| #endif |
| |
| return 0; |
| } |