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			135 lines
		
	
	
		
			4.5 KiB
		
	
	
	
		
			C
		
	
	
	
	
	
			
		
		
	
	
			135 lines
		
	
	
		
			4.5 KiB
		
	
	
	
		
			C
		
	
	
	
	
	
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/* arm_init.c - NEON optimised filter functions
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 *
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 * Copyright (c) 2014 Glenn Randers-Pehrson
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 * Written by Mans Rullgard, 2011.
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 * Last changed in libpng 1.6.16 [(PENDING RELEASE)]
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 *
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 * This code is released under the libpng license.
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 * For conditions of distribution and use, see the disclaimer
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 * and license in png.h
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 */
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/* Below, after checking __linux__, various non-C90 POSIX 1003.1 functions are
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 * called.
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 */
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#define _POSIX_SOURCE 1
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#include "../pngpriv.h"
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#ifdef PNG_READ_SUPPORTED
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#if PNG_ARM_NEON_OPT > 0
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#ifdef PNG_ARM_NEON_CHECK_SUPPORTED /* Do run-time checks */
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/* WARNING: it is strongly recommended that you do not build libpng with
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 * run-time checks for CPU features if at all possible.  In the case of the ARM
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 * NEON instructions there is no processor-specific way of detecting the
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 * presence of the required support, therefore run-time detection is extremely
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 * OS specific.
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 *
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 * You may set the macro PNG_ARM_NEON_FILE to the file name of file containing
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 * a fragment of C source code which defines the png_have_neon function.  There
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 * are a number of implementations in contrib/arm-neon, but the only one that
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 * has partial support is contrib/arm-neon/linux.c - a generic Linux
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 * implementation which reads /proc/cpufino.
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 */
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#ifndef PNG_ARM_NEON_FILE
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#  ifdef __linux__
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#     define PNG_ARM_NEON_FILE "contrib/arm-neon/linux.c"
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#  endif
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#endif
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#ifdef PNG_ARM_NEON_FILE
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#include <signal.h> /* for sig_atomic_t */
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static int png_have_neon(png_structp png_ptr);
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#include PNG_ARM_NEON_FILE
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#else  /* PNG_ARM_NEON_FILE */
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#  error "PNG_ARM_NEON_FILE undefined: no support for run-time ARM NEON checks"
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#endif /* PNG_ARM_NEON_FILE */
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#endif /* PNG_ARM_NEON_CHECK_SUPPORTED */
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#ifndef PNG_ALIGNED_MEMORY_SUPPORTED
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#  error "ALIGNED_MEMORY is required; set: -DPNG_ALIGNED_MEMORY_SUPPORTED"
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#endif
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void
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png_init_filter_functions_neon(png_structp pp, unsigned int bpp)
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{
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   /* The switch statement is compiled in for ARM_NEON_API, the call to
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    * png_have_neon is compiled in for ARM_NEON_CHECK.  If both are defined
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    * the check is only performed if the API has not set the NEON option on
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    * or off explicitly.  In this case the check controls what happens.
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    *
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    * If the CHECK is not compiled in and the option is UNSET the behavior prior
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    * to 1.6.7 was to use the NEON code - this was a bug caused by having the
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    * wrong order of the 'ON' and 'default' cases.  UNSET now defaults to OFF,
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    * as documented in png.h
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    */
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#ifdef PNG_ARM_NEON_API_SUPPORTED
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   switch ((pp->options >> PNG_ARM_NEON) & 3)
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   {
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      case PNG_OPTION_UNSET:
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         /* Allow the run-time check to execute if it has been enabled -
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          * thus both API and CHECK can be turned on.  If it isn't supported
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          * this case will fall through to the 'default' below, which just
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          * returns.
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          */
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#endif /* PNG_ARM_NEON_API_SUPPORTED */
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#ifdef PNG_ARM_NEON_CHECK_SUPPORTED
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         {
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            static volatile sig_atomic_t no_neon = -1; /* not checked */
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            if (no_neon < 0)
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               no_neon = !png_have_neon(pp);
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            if (no_neon)
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               return;
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         }
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#ifdef PNG_ARM_NEON_API_SUPPORTED
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         break;
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#endif
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#endif /* PNG_ARM_NEON_CHECK_SUPPORTED */
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#ifdef PNG_ARM_NEON_API_SUPPORTED
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      default: /* OFF or INVALID */
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         return;
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      case PNG_OPTION_ON:
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         /* Option turned on */
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         break;
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   }
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#endif
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   /* IMPORTANT: any new external functions used here must be declared using
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    * PNG_INTERNAL_FUNCTION in ../pngpriv.h.  This is required so that the
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    * 'prefix' option to configure works:
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    *
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    *    ./configure --with-libpng-prefix=foobar_
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    *
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    * Verify you have got this right by running the above command, doing a build
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    * and examining pngprefix.h; it must contain a #define for every external
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    * function you add.  (Notice that this happens automatically for the
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    * initialization function.)
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    */
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   pp->read_filter[PNG_FILTER_VALUE_UP-1] = png_read_filter_row_up_neon;
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   if (bpp == 3)
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   {
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      pp->read_filter[PNG_FILTER_VALUE_SUB-1] = png_read_filter_row_sub3_neon;
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      pp->read_filter[PNG_FILTER_VALUE_AVG-1] = png_read_filter_row_avg3_neon;
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      pp->read_filter[PNG_FILTER_VALUE_PAETH-1] =
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         png_read_filter_row_paeth3_neon;
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   }
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   else if (bpp == 4)
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   {
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      pp->read_filter[PNG_FILTER_VALUE_SUB-1] = png_read_filter_row_sub4_neon;
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      pp->read_filter[PNG_FILTER_VALUE_AVG-1] = png_read_filter_row_avg4_neon;
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      pp->read_filter[PNG_FILTER_VALUE_PAETH-1] =
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          png_read_filter_row_paeth4_neon;
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   }
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}
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#endif /* PNG_ARM_NEON_OPT > 0 */
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#endif /* READ */
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