dba54b8888
implementation of the ARM NEON discovery function to be set at build-time and provide sample implementations from the current code in the contrib/arm-neon subdirectory. The __linux__ code has also been changed to compile and link on Android by using /proc/cpuinfo, and the old linux code is in contrib/arm-neon/linux-auxv.c. The new code avoids POSIX and Linux dependencies apart from opening /proc/cpuinfo and is C90 compliant.
134 lines
4.5 KiB
C
134 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) 2013 Glenn Randers-Pehrson
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* Written by Mans Rullgard, 2011.
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* Last changed in libpng 1.6.8 [December 19, 2013]
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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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* presense of the required support, therefore run-time detectioon 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 /* PNG_READ_SUPPORTED */
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