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 */
 44static 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
 56void
 57png_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 */