mirror of
https://git.code.sf.net/p/libpng/code.git
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233 lines
6.8 KiB
C
233 lines
6.8 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 1.6.6 [September 16, 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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#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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/* 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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