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/* arm_init.c - NEON optimised filter functions
*
* Copyright (c) 2014,2016 Glenn Randers-Pehrson
* Written by Mans Rullgard, 2011.
* Last changed in libpng 1.6.22 [June 9, 2016]
*
* This code is released under the libpng license.
* For conditions of distribution and use, see the disclaimer
* and license in png.h
*/
/* Below, after checking __linux__, various non-C90 POSIX 1003.1 functions are
* called.
*/
#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.
*/
#ifndef PNG_ARM_NEON_FILE
# ifdef __linux__
# define PNG_ARM_NEON_FILE "contrib/arm-neon/linux.c"
# endif
#endif
#ifdef PNG_ARM_NEON_FILE
#include <signal.h> /* for sig_atomic_t */
static int png_have_neon(png_structp png_ptr);
#include PNG_ARM_NEON_FILE
#else /* PNG_ARM_NEON_FILE */
# error "PNG_ARM_NEON_FILE undefined: no support for run-time ARM NEON checks"
#endif /* PNG_ARM_NEON_FILE */
#endif /* PNG_ARM_NEON_CHECK_SUPPORTED */
#ifndef PNG_ALIGNED_MEMORY_SUPPORTED
# error "ALIGNED_MEMORY is required; set: -DPNG_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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