diff options
Diffstat (limited to 'arm/arm_init.c')
| -rw-r--r-- | arm/arm_init.c | 147 |
1 files changed, 24 insertions, 123 deletions
diff --git a/arm/arm_init.c b/arm/arm_init.c index 271c6121d..952b8029f 100644 --- a/arm/arm_init.c +++ b/arm/arm_init.c @@ -1,9 +1,9 @@ /* arm_init.c - NEON optimised filter functions * - * Copyright (c) 2013 Glenn Randers-Pehrson + * Copyright (c) 2014 Glenn Randers-Pehrson * Written by Mans Rullgard, 2011. - * Last changed in libpng 1.6.6 [September 16, 2013] + * Last changed in libpng 1.6.10 [March 6, 2014] * * This code is released under the libpng license. * For conditions of distribution and use, see the disclaimer @@ -19,132 +19,33 @@ #ifdef PNG_READ_SUPPORTED #if PNG_ARM_NEON_OPT > 0 #ifdef PNG_ARM_NEON_CHECK_SUPPORTED /* Do run-time checks */ -#include <signal.h> /* for sig_atomic_t */ - -#ifdef __ANDROID__ -/* Linux provides access to information about CPU capabilites via - * /proc/self/auxv, however Android blocks this while still claiming to be - * Linux. The Andoid NDK, however, provides appropriate support. +/* 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 + * presense of the required support, therefore run-time detectioon is extremely + * OS specific. * - * Documentation: http://www.kandroid.org/ndk/docs/CPU-ARM-NEON.html - */ -#include <cpu-features.h> - -static int -png_have_neon(png_structp png_ptr) -{ - /* This is a whole lot easier than the mess below, however it is probably - * implemented as below, therefore it is better to cache the result (these - * function calls may be slow!) - */ - PNG_UNUSED(png_ptr) - return android_getCpuFamily() == ANDROID_CPU_FAMILY_ARM && - (android_getCpuFeatures() & ANDROID_CPU_ARM_FEATURE_NEON) != 0; -} -#elif defined(__linux__) -/* The generic __linux__ implementation requires reading /proc/self/auxv and - * looking at each element for one that records NEON capabilities. - */ -#include <unistd.h> /* for POSIX 1003.1 */ -#include <errno.h> /* for EINTR */ - -#include <sys/types.h> -#include <sys/stat.h> -#include <fcntl.h> -#include <elf.h> -#include <asm/hwcap.h> - -/* A read call may be interrupted, in which case it returns -1 and sets errno to - * EINTR if nothing was done, otherwise (if something was done) a partial read - * may result. + * 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. */ -static size_t -safe_read(png_structp png_ptr, int fd, void *buffer_in, size_t nbytes) -{ - size_t ntotal = 0; - char *buffer = png_voidcast(char*, buffer_in); - - while (nbytes > 0) - { - unsigned int nread; - int iread; - - /* Passing nread > INT_MAX to read is implementation defined in POSIX - * 1003.1, therefore despite the unsigned argument portable code must - * limit the value to INT_MAX! - */ - if (nbytes > INT_MAX) - nread = INT_MAX; - - else - nread = (unsigned int)/*SAFE*/nbytes; - - iread = read(fd, buffer, nread); - - if (iread == -1) - { - /* This is the devil in the details, a read can terminate early with 0 - * bytes read because of EINTR, yet it still returns -1 otherwise end - * of file cannot be distinguished. - */ - if (errno != EINTR) - { - png_warning(png_ptr, "/proc read failed"); - return 0; /* I.e., a permanent failure */ - } - } - - else if (iread < 0) - { - /* Not a valid 'read' result: */ - png_warning(png_ptr, "OS /proc read bug"); - return 0; - } - - else if (iread > 0) - { - /* Continue reading until a permanent failure, or EOF */ - buffer += iread; - nbytes -= (unsigned int)/*SAFE*/iread; - ntotal += (unsigned int)/*SAFE*/iread; - } - - else - return ntotal; - } - - return ntotal; /* nbytes == 0 */ -} - -static int -png_have_neon(png_structp png_ptr) -{ - int fd = open("/proc/self/auxv", O_RDONLY); - Elf32_auxv_t aux; +#ifndef PNG_ARM_NEON_FILE +# ifdef __linux__ +# define PNG_ARM_NEON_FILE "contrib/arm-neon/linux.c" +# endif +#endif - /* Failsafe: failure to open means no NEON */ - if (fd == -1) - { - png_warning(png_ptr, "/proc/self/auxv open failed"); - return 0; - } +#ifdef PNG_ARM_NEON_FILE - while (safe_read(png_ptr, fd, &aux, sizeof aux) == sizeof aux) - { - if (aux.a_type == AT_HWCAP && (aux.a_un.a_val & HWCAP_NEON) != 0) - { - close(fd); - return 1; - } - } +#include <signal.h> /* for sig_atomic_t */ +static int png_have_neon(png_structp png_ptr); +#include PNG_ARM_NEON_FILE - close(fd); - return 0; -} -#else - /* We don't know how to do a run-time check on this system */ -# error "no support for run-time ARM NEON checks" -#endif /* OS checks */ +#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 |