source/libs/libpng/libpng-src/arm/arm_init.c

   1
   2 /* arm_init.c - NEON optimised filter functions
   3  *
   4  * Copyright (c) 2014,2016 Glenn Randers-Pehrson
   5  * Written by Mans Rullgard, 2011.
   6  * Last changed in libpng 1.6.22 [May 26, 2016]
   7  *
   8  * This code is released under the libpng license.
   9  * For conditions of distribution and use, see the disclaimer
  10  * and license in png.h
  11  */
  12 /* Below, after checking __linux__, various non-C90 POSIX 1003.1 functions are
  13  * called.
  14  */
  15 #define _POSIX_SOURCE 1
  16
  17 #include "../pngpriv.h"
  18
  19 #ifdef PNG_READ_SUPPORTED
  20
  21 #if PNG_ARM_NEON_OPT > 0
  22 #ifdef PNG_ARM_NEON_CHECK_SUPPORTED /* Do run-time checks */
  23 /* WARNING: it is strongly recommended that you do not build libpng with
  24  * run-time checks for CPU features if at all possible.  In the case of the ARM
  25  * NEON instructions there is no processor-specific way of detecting the
  26  * presence of the required support, therefore run-time detection is extremely
  27  * OS specific.
  28  *
  29  * You may set the macro PNG_ARM_NEON_FILE to the file name of file containing
  30  * a fragment of C source code which defines the png_have_neon function.  There
  31  * are a number of implementations in contrib/arm-neon, but the only one that
  32  * has partial support is contrib/arm-neon/linux.c - a generic Linux
  33  * implementation which reads /proc/cpufino.
  34  */
  35 #ifndef PNG_ARM_NEON_FILE
  36 #  ifdef __linux__
  37 #     define PNG_ARM_NEON_FILE "contrib/arm-neon/linux.c"
  38 #  endif
  39 #endif
  40
  41 #ifdef PNG_ARM_NEON_FILE
  42
  43 #include <signal.h> /* for sig_atomic_t */
  44 static int png_have_neon(png_structp png_ptr);
  45 #include PNG_ARM_NEON_FILE
  46
  47 #else  /* PNG_ARM_NEON_FILE */
  48 #  error "PNG_ARM_NEON_FILE undefined: no support for run-time ARM NEON checks"
  49 #endif /* PNG_ARM_NEON_FILE */
  50 #endif /* PNG_ARM_NEON_CHECK_SUPPORTED */
  51
  52 #ifndef PNG_ALIGNED_MEMORY_SUPPORTED
  53 #  error "ALIGNED_MEMORY is required; set: -DPNG_ALIGNED_MEMORY_SUPPORTED"
  54 #endif
  55
  56 void
  57 png_init_filter_functions_neon(png_structp pp, unsigned int bpp)
  58 {
  59    /* The switch statement is compiled in for ARM_NEON_API, the call to
  60     * png_have_neon is compiled in for ARM_NEON_CHECK.  If both are defined
  61     * the check is only performed if the API has not set the NEON option on
  62     * or off explicitly.  In this case the check controls what happens.
  63     *
  64     * If the CHECK is not compiled in and the option is UNSET the behavior prior
  65     * to 1.6.7 was to use the NEON code - this was a bug caused by having the
  66     * wrong order of the 'ON' and 'default' cases.  UNSET now defaults to OFF,
  67     * as documented in png.h
  68     */
  69    png_debug(1, "in png_init_filter_functions_neon");
  70 #ifdef PNG_ARM_NEON_API_SUPPORTED
  71    switch ((pp->options >> PNG_ARM_NEON) & 3)
  72    {
  73       case PNG_OPTION_UNSET:
  74          /* Allow the run-time check to execute if it has been enabled -
  75           * thus both API and CHECK can be turned on.  If it isn't supported
  76           * this case will fall through to the 'default' below, which just
  77           * returns.
  78           */
  79 #endif /* PNG_ARM_NEON_API_SUPPORTED */
  80 #ifdef PNG_ARM_NEON_CHECK_SUPPORTED
  81          {
  82             static volatile sig_atomic_t no_neon = -1; /* not checked */
  83
  84             if (no_neon < 0)
  85                no_neon = !png_have_neon(pp);
  86
  87             if (no_neon)
  88                return;
  89          }
  90 #ifdef PNG_ARM_NEON_API_SUPPORTED
  91          break;
  92 #endif
  93 #endif /* PNG_ARM_NEON_CHECK_SUPPORTED */
  94
  95 #ifdef PNG_ARM_NEON_API_SUPPORTED
  96       default: /* OFF or INVALID */
  97          return;
  98
  99       case PNG_OPTION_ON:
 100          /* Option turned on */
 101          break;
 102    }
 103 #endif
 104
 105    /* IMPORTANT: any new external functions used here must be declared using
 106     * PNG_INTERNAL_FUNCTION in ../pngpriv.h.  This is required so that the
 107     * 'prefix' option to configure works:
 108     *
 109     *    ./configure --with-libpng-prefix=foobar_
 110     *
 111     * Verify you have got this right by running the above command, doing a build
 112     * and examining pngprefix.h; it must contain a #define for every external
 113     * function you add.  (Notice that this happens automatically for the
 114     * initialization function.)
 115     */
 116    pp->read_filter[PNG_FILTER_VALUE_UP-1] = png_read_filter_row_up_neon;
 117
 118    if (bpp == 3)
 119    {
 120       pp->read_filter[PNG_FILTER_VALUE_SUB-1] = png_read_filter_row_sub3_neon;
 121       pp->read_filter[PNG_FILTER_VALUE_AVG-1] = png_read_filter_row_avg3_neon;
 122       pp->read_filter[PNG_FILTER_VALUE_PAETH-1] =
 123          png_read_filter_row_paeth3_neon;
 124    }
 125
 126    else if (bpp == 4)
 127    {
 128       pp->read_filter[PNG_FILTER_VALUE_SUB-1] = png_read_filter_row_sub4_neon;
 129       pp->read_filter[PNG_FILTER_VALUE_AVG-1] = png_read_filter_row_avg4_neon;
 130       pp->read_filter[PNG_FILTER_VALUE_PAETH-1] =
 131           png_read_filter_row_paeth4_neon;
 132    }
 133 }
 134 #endif /* PNG_ARM_NEON_OPT > 0 */
 135 #endif /* READ */