/* arm_init.c - NEON optimised filter functions * * Copyright (c) 2013 Glenn Randers-Pehrson * Written by Mans Rullgard, 2011. * Last changed in libpng 1.6.8 [December 19, 2013] * * 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 */ #include /* 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. * * Documentation: http://www.kandroid.org/ndk/docs/CPU-ARM-NEON.html */ #include 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 /* for POSIX 1003.1 */ #include /* for EINTR */ #include #include #include #include #include /* 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. */ 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; /* Failsafe: failure to open means no NEON */ if (fd == -1) { png_warning(png_ptr, "/proc/self/auxv open failed"); return 0; } 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; } } 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 */ #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 */ #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 /* PNG_READ_SUPPORTED */