diff options
Diffstat (limited to 'contrib/arm-neon')
| -rw-r--r-- | contrib/arm-neon/README | 83 | ||||
| -rw-r--r-- | contrib/arm-neon/android-ndk.c | 39 | ||||
| -rw-r--r-- | contrib/arm-neon/linux-auxv.c | 120 | ||||
| -rw-r--r-- | contrib/arm-neon/linux.c | 159 |
4 files changed, 401 insertions, 0 deletions
diff --git a/contrib/arm-neon/README b/contrib/arm-neon/README new file mode 100644 index 000000000..535c8d3f7 --- /dev/null +++ b/contrib/arm-neon/README @@ -0,0 +1,83 @@ +OPERATING SYSTEM SPECIFIC ARM NEON DETECTION +-------------------------------------------- + +Detection of the ability to exexcute ARM NEON on an ARM processor requires +operating system support. (The information is not available in user mode.) + +HOW TO USE THIS +--------------- + +This directory contains C code fragments that can be included in arm/arm_init.c +by setting the macro PNG_ARM_NEON_FILE to the file name in "" or <> at build +time. This setting is not recorded in pnglibconf.h and can be changed simply by +rebuilding arm/arm_init.o with the required macro definition. + +For any of this code to be used the ARM NEON code must be enabled and run time +checks must be supported. I.e.: + +#if PNG_ARM_NEON_OPT > 0 +#ifdef PNG_ARM_NEON_CHECK_SUPPORTED + +This is done in a 'configure' build by passing configure the argument: + + --enable-arm-neon=check + +Apart from the basic Linux implementation in contrib/arm-neon/linux.c this code +is unsupported. That means that it is not even compiled on a regular basis and +may be broken in any given minor release. + +FILE FORMAT +----------- + +Each file documents its testing status as of the last time it was tested (which +may have been a long time ago): + +STATUS: one of: + SUPPORTED: This indicates that the file is included in the regularly + performed test builds and bugs are fixed when discovered. + COMPILED: This indicates that the code did compile at least once. See the + more detailed description for the extent to which the result was + successful. + TESTED: This means the code was fully compiled into the libpng test programs + and these were run at least once. + +BUG REPORTS: an email address to which to send reports of problems + +The file is a fragment of C code. It should not define any 'extern' symbols; +everything should be static. It must define the function: + +static int png_have_neon(png_structp png_ptr); + +That function must return 1 if ARM NEON instructions are supported, 0 if not. +It must not execute png_error unless it detects a bug. A png_error will prevent +the reading of the PNG and in the future, writing too. + +BUG REPORTS +----------- + +If you mail a bug report for any file that is not SUPPORTED there may only be +limited response. Consider fixing it and sending a patch to fix the problem - +this is more likely to result in action. + +CONTRIBUTIONS +------------- + +You may send contributions of new implementations to +png-mng-implement@sourceforge.net. Please write code in strict C90 C where +possible. Obviously OS dependencies are to be expected. If you submit code you +must have the authors permission and it must have a license that is acceptable +to the current maintainer; in particular that license must permit modification +and redistribution. + +Please try to make the contribution a single file and give the file a clear and +unambiguous name that identifies the target OS. If multiple files really are +required put them all in a sub-directory. + +You must also be prepared to handle bug reports from users of the code, either +by joining the png-mng-implement mailing list or by providing an email for the +"BUG REPORTS" entry or both. Please make sure that the header of the file +contains the STATUS and BUG REPORTS fields as above. + +Please list the OS requirements as precisely as possible. Ideally you should +also list the environment in which the code has been tested and certainly list +any environments where you suspect it might not work. diff --git a/contrib/arm-neon/android-ndk.c b/contrib/arm-neon/android-ndk.c new file mode 100644 index 000000000..724012348 --- /dev/null +++ b/contrib/arm-neon/android-ndk.c @@ -0,0 +1,39 @@ +/* contrib/arm-neon/android-ndk.c + * + * Copyright (c) 2014 Glenn Randers-Pehrson + * Written by John Bowler, 2014. + * 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 + * and license in png.h + * + * SEE contrib/arm-neon/README before reporting bugs + * + * STATUS: COMPILED, UNTESTED + * BUG REPORTS: png-mng-implement@sourceforge.net + * + * png_have_neon implemented for the Android NDK, see: + * + * Documentation: + * http://www.kandroid.org/ndk/docs/CPU-ARM-NEON.html + * http://code.google.com/p/android/issues/detail?id=49065 + * + * NOTE: this requires that libpng is built against the Android NDK and linked + * with an implementation of the Android ARM 'cpu-features' library. The code + * has been compiled only, not linked: no version of the library has been found, + * only the header files exist in the NDK. + */ +#include <cpu-features.h> + +static int +png_have_neon(png_structp png_ptr) +{ + /* This is a whole lot easier than the linux code, 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; +} diff --git a/contrib/arm-neon/linux-auxv.c b/contrib/arm-neon/linux-auxv.c new file mode 100644 index 000000000..696e297ef --- /dev/null +++ b/contrib/arm-neon/linux-auxv.c @@ -0,0 +1,120 @@ +/* contrib/arm-neon/linux-auxv.c + * + * Copyright (c) 2014 Glenn Randers-Pehrson + * Written by Mans Rullgard, 2011. + * 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 + * and license in png.h + * + * SEE contrib/arm-neon/README before reporting bugs + * + * STATUS: COMPILED, TESTED + * BUG REPORTS: png-mng-implement@sourceforge.net + * + * png_have_neon implemented for Linux versions which allow access to + * /proc/self/auxv. This is probably faster, cleaner and safer than the code to + * read /proc/cpuinfo in contrib/arm-neon/linux, however it is yet another piece + * of potentially untested code and has more complex dependencies than the code + * to read cpuinfo. + * + * This 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. + */ +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; +} diff --git a/contrib/arm-neon/linux.c b/contrib/arm-neon/linux.c new file mode 100644 index 000000000..182f37605 --- /dev/null +++ b/contrib/arm-neon/linux.c @@ -0,0 +1,159 @@ +/* contrib/arm-neon/linux.c + * + * Copyright (c) 2014 Glenn Randers-Pehrson + * Written by John Bowler, 2014. + * 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 + * and license in png.h + * + * SEE contrib/arm-neon/README before reporting bugs + * + * STATUS: SUPPORTED + * BUG REPORTS: png-mng-implement@sourceforge.net + * + * png_have_neon implemented for Linux by reading the widely available + * pseudo-file /proc/cpuinfo. + * + * This code is strict ANSI-C and is probably moderately portable, it does + * however use <stdio.h> and assumes that /proc/cpuinfo is never localized. + */ +#include <stdio.h> + +static int +png_have_neon(png_structp png_ptr) +{ + FILE *f = fopen("/proc/cpuinfo", "rb"); + + if (f != NULL) + { + /* This is a simple state machine which reads the input byte-by-byte until + * it gets a match on the 'neon' feature or reaches the end of the stream. + */ + static const char ch_feature[] = { 70, 69, 65, 84, 85, 82, 69, 83 }; + static const char ch_neon[] = { 78, 69, 79, 78 }; + + enum + { + StartLine, Feature, Colon, StartTag, Neon, HaveNeon, SkipTag, SkipLine + } state; + int counter; + + for (state=StartLine, counter=0;;) + { + int ch = fgetc(f); + + if (ch == EOF) + { + /* EOF means error or end-of-file, return false; neon at EOF is + * assumed to be a mistake. + */ + fclose(f); + return 0; + } + + switch (state) + { + case StartLine: + /* Match spaces at the start of line */ + if (ch <= 32) /* skip control characters and space */ + break; + + counter=0; + state = Feature; + /* FALL THROUGH */ + + case Feature: + /* Match 'FEATURE', ASCII case insensitive. */ + if ((ch & ~0x20) == ch_feature[counter]) + { + if (++counter == (sizeof ch_feature)) + state = Colon; + break; + } + + /* did not match 'feature' */ + state = SkipLine; + /* FALL THROUGH */ + + case SkipLine: + skipLine: + /* Skip everything until we see linefeed or carriage return */ + if (ch != 10 && ch != 13) + break; + + state = StartLine; + break; + + case Colon: + /* Match any number of space or tab followed by ':' */ + if (ch == 32 || ch == 9) + break; + + if (ch == 58) /* i.e. ':' */ + { + state = StartTag; + break; + } + + /* Either a bad line format or a 'feature' prefix followed by + * other characters. + */ + state = SkipLine; + goto skipLine; + + case StartTag: + /* Skip space characters before a tag */ + if (ch == 32 || ch == 9) + break; + + state = Neon; + counter = 0; + /* FALL THROUGH */ + + case Neon: + /* Look for 'neon' tag */ + if ((ch & ~0x20) == ch_neon[counter]) + { + if (++counter == (sizeof ch_neon)) + state = HaveNeon; + break; + } + + state = SkipTag; + /* FALL THROUGH */ + + case SkipTag: + /* Skip non-space characters */ + if (ch == 10 || ch == 13) + state = StartLine; + + else if (ch == 32 || ch == 9) + state = StartTag; + break; + + case HaveNeon: + /* Have seen a 'neon' prefix, but there must be a space or new + * line character to terminate it. + */ + if (ch == 10 || ch == 13 || ch == 32 || ch == 9) + { + fclose(f); + return 1; + } + + state = SkipTag; + break; + + default: + png_error(png_ptr, "png_have_neon: internal error (bug)"); + } + } + } + + else + png_warning(png_ptr, "/proc/cpuinfo open failed"); + + return 0; +} |