18dd07e3e6
pnglibconf.h, allowing more of the decisions to be made internally
(pngpriv.h) during the compile. Without this, symbol prefixing is broken
under certain circumstances on ARM platforms. Now only the API parts of
the optimizations ('check' vs 'api') are exposed in the public header files
except that the new setting PNG_ARM_NEON_OPT documents how libpng makes the
decision about whether or not to use the optimizations.
220 lines
6.2 KiB
C
220 lines
6.2 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 1.5.16 [(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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#if PNG_ARM_NEON_OPT > 0
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#ifdef PNG_ARM_NEON_CHECK_SUPPORTED /* Do run-time checks */
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#include <signal.h> /* for sig_atomic_t */
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#ifdef __ANDROID__
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/* Linux provides access to information about CPU capabilites via
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* /proc/self/auxv, however Android blocks this while still claiming to be
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* Linux. The Andoid NDK, however, provides appropriate support.
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*
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* Documentation: http://www.kandroid.org/ndk/docs/CPU-ARM-NEON.html
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*/
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#include <cpu-features.h>
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static int
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png_have_neon(png_structp png_ptr)
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{
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/* This is a whole lot easier than the mess below, however it is probably
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* implemented as below, therefore it is better to cache the result (these
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* function calls may be slow!)
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*/
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PNG_UNUSED(png_ptr)
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return android_getCpuFamily() == ANDROID_CPU_FAMILY_ARM &&
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(android_getCpuFeatures() & ANDROID_CPU_ARM_FEATURE_NEON) != 0;
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}
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#elif defined(__linux__)
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/* The generic __linux__ implementation requires reading /proc/self/auxv and
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* looking at each element for one that records NEON capabilities.
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*/
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#include <unistd.h> /* for POSIX 1003.1 */
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#include <errno.h> /* for EINTR */
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#include <sys/types.h>
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#include <sys/stat.h>
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#include <fcntl.h>
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#include <elf.h>
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#include <asm/hwcap.h>
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/* A read call may be interrupted, in which case it returns -1 and sets errno to
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* EINTR if nothing was done, otherwise (if something was done) a partial read
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* may result.
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*/
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static size_t
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safe_read(png_structp png_ptr, int fd, void *buffer_in, size_t nbytes)
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{
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size_t ntotal = 0;
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char *buffer = png_voidcast(char*, buffer_in);
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while (nbytes > 0)
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{
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unsigned int nread;
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int iread;
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/* Passing nread > INT_MAX to read is implementation defined in POSIX
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* 1003.1, therefore despite the unsigned argument portable code must
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* limit the value to INT_MAX!
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*/
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if (nbytes > INT_MAX)
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nread = INT_MAX;
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else
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nread = (unsigned int)/*SAFE*/nbytes;
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iread = read(fd, buffer, nread);
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if (iread == -1)
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{
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/* This is the devil in the details, a read can terminate early with 0
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* bytes read because of EINTR, yet it still returns -1 otherwise end
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* of file cannot be distinguished.
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*/
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if (errno != EINTR)
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{
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png_warning(png_ptr, "/proc read failed");
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return 0; /* I.e. a permanent failure */
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}
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}
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else if (iread < 0)
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{
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/* Not a valid 'read' result: */
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png_warning(png_ptr, "OS /proc read bug");
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return 0;
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}
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else if (iread > 0)
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{
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/* Continue reading until a permanent failure, or EOF */
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buffer += iread;
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nbytes -= (unsigned int)/*SAFE*/iread;
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ntotal += (unsigned int)/*SAFE*/iread;
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}
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else
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return ntotal;
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}
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return ntotal; /* nbytes == 0 */
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}
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static int
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png_have_neon(png_structp png_ptr)
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{
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int fd = open("/proc/self/auxv", O_RDONLY);
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Elf32_auxv_t aux;
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/* Failsafe: failure to open means no NEON */
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if (fd == -1)
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{
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png_warning(png_ptr, "/proc/self/auxv open failed");
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return 0;
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}
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while (safe_read(png_ptr, fd, &aux, sizeof aux) == sizeof aux)
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{
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if (aux.a_type == AT_HWCAP && (aux.a_un.a_val & HWCAP_NEON) != 0)
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{
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close(fd);
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return 1;
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}
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}
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close(fd);
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return 0;
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}
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#else
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/* We don't know how to do a run-time check on this system */
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# error "no support for run-time ARM NEON checks"
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#endif /* OS checks */
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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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#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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case PNG_OPTION_ON:
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/* Option turned on */
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break;
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default: /* OFF or INVALID */
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return;
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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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