kc3-lang/libpng/arm/arm_init.c

Branch - branch -libpng16libpng17

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• Hash : 69a3e5bf
  Author :
  Date : 2025-04-25T16:19:30
  

  chore: Clean up the error directives
  
  Make the error directives uniformly consistent with one another.
  Remove surrounding quotes and trailing punctuation, and rephrase
  some of the error messages and some of their associated comments
  for either brevity or clarity.
  

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• arm/arm_init.c

• /* arm_init.c - NEON optimised filter functions
   *
   * Copyright (c) 2018-2022 Cosmin Truta
   * Copyright (c) 2014,2016 Glenn Randers-Pehrson
   * Written by Mans Rullgard, 2011.
   *
   * This code is released under the libpng license.
   * For conditions of distribution and use, see the disclaimer
   * and license in png.h
   */
  
  /* This module requires POSIX 1003.1 functions. */
  #define _POSIX_SOURCE 1
  
  #include "../pngpriv.h"
  
  #ifdef PNG_READ_SUPPORTED
  
  #if PNG_ARM_NEON_OPT > 0
  #ifdef PNG_ARM_NEON_CHECK_SUPPORTED /* Do run-time checks */
  /* WARNING: it is strongly recommended that you do not build libpng with
   * run-time checks for CPU features if at all possible.  In the case of the ARM
   * NEON instructions there is no processor-specific way of detecting the
   * presence of the required support, therefore run-time detection is extremely
   * OS specific.
   *
   * You may set the macro PNG_ARM_NEON_FILE to the file name of file containing
   * a fragment of C source code which defines the png_have_neon function.  There
   * are a number of implementations in contrib/arm-neon, but the only one that
   * has partial support is contrib/arm-neon/linux.c - a generic Linux
   * implementation which reads /proc/cpufino.
   */
  #include <signal.h> /* for sig_atomic_t */
  
  #ifndef PNG_ARM_NEON_FILE
  #  if defined(__aarch64__) || defined(_M_ARM64)
       /* ARM Neon is expected to be unconditionally available on ARM64. */
  #    error PNG_ARM_NEON_CHECK_SUPPORTED must not be defined on ARM64
  #  elif defined(__ARM_NEON__) || defined(__ARM_NEON)
       /* ARM Neon is expected to be available on the target CPU architecture. */
  #    error PNG_ARM_NEON_CHECK_SUPPORTED must not be defined on this CPU arch
  #  elif defined(__linux__)
  #    define PNG_ARM_NEON_FILE "contrib/arm-neon/linux.c"
  #  else
  #    error No support for run-time ARM Neon checking; use compile-time options
  #  endif
  #endif
  
  static int png_have_neon(png_structp png_ptr);
  #ifdef PNG_ARM_NEON_FILE
  #  include PNG_ARM_NEON_FILE
  #endif
  #endif /* PNG_ARM_NEON_CHECK_SUPPORTED */
  
  #ifndef PNG_ALIGNED_MEMORY_SUPPORTED
  #  error ALIGNED_MEMORY is required; please define PNG_ALIGNED_MEMORY_SUPPORTED
  #endif
  
  void
  png_init_filter_functions_neon(png_structp pp, unsigned int bpp)
  {
     /* The switch statement is compiled in for ARM_NEON_API, the call to
      * png_have_neon is compiled in for ARM_NEON_CHECK.  If both are defined
      * the check is only performed if the API has not set the NEON option on
      * or off explicitly.  In this case the check controls what happens.
      *
      * If the CHECK is not compiled in and the option is UNSET the behavior prior
      * to 1.6.7 was to use the NEON code - this was a bug caused by having the
      * wrong order of the 'ON' and 'default' cases.  UNSET now defaults to OFF,
      * as documented in png.h
      */
     png_debug(1, "in png_init_filter_functions_neon");
  #ifdef PNG_ARM_NEON_API_SUPPORTED
     switch ((pp->options >> PNG_ARM_NEON) & 3)
     {
        case PNG_OPTION_UNSET:
           /* Allow the run-time check to execute if it has been enabled -
            * thus both API and CHECK can be turned on.  If it isn't supported
            * this case will fall through to the 'default' below, which just
            * returns.
            */
  #endif /* PNG_ARM_NEON_API_SUPPORTED */
  #ifdef PNG_ARM_NEON_CHECK_SUPPORTED
           {
              static volatile sig_atomic_t no_neon = -1; /* not checked */
  
              if (no_neon < 0)
                 no_neon = !png_have_neon(pp);
  
              if (no_neon)
                 return;
           }
  #ifdef PNG_ARM_NEON_API_SUPPORTED
           break;
  #endif
  #endif /* PNG_ARM_NEON_CHECK_SUPPORTED */
  
  #ifdef PNG_ARM_NEON_API_SUPPORTED
        default: /* OFF or INVALID */
           return;
  
        case PNG_OPTION_ON:
           /* Option turned on */
           break;
     }
  #endif
  
     /* IMPORTANT: any new external functions used here must be declared using
      * PNG_INTERNAL_FUNCTION in ../pngpriv.h.  This is required so that the
      * 'prefix' option to configure works:
      *
      *    ./configure --with-libpng-prefix=foobar_
      *
      * Verify you have got this right by running the above command, doing a build
      * and examining pngprefix.h; it must contain a #define for every external
      * function you add.  (Notice that this happens automatically for the
      * initialization function.)
      */
     pp->read_filter[PNG_FILTER_VALUE_UP-1] = png_read_filter_row_up_neon;
  
     if (bpp == 3)
     {
        pp->read_filter[PNG_FILTER_VALUE_SUB-1] = png_read_filter_row_sub3_neon;
        pp->read_filter[PNG_FILTER_VALUE_AVG-1] = png_read_filter_row_avg3_neon;
        pp->read_filter[PNG_FILTER_VALUE_PAETH-1] =
           png_read_filter_row_paeth3_neon;
     }
  
     else if (bpp == 4)
     {
        pp->read_filter[PNG_FILTER_VALUE_SUB-1] = png_read_filter_row_sub4_neon;
        pp->read_filter[PNG_FILTER_VALUE_AVG-1] = png_read_filter_row_avg4_neon;
        pp->read_filter[PNG_FILTER_VALUE_PAETH-1] =
            png_read_filter_row_paeth4_neon;
     }
  }
  #endif /* PNG_ARM_NEON_OPT > 0 */
  #endif /* READ */
  

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