2 /* arm_init.c - NEON optimised filter functions
4 * Copyright (c) 2013 Glenn Randers-Pehrson
5 * Written by Mans Rullgard, 2011.
6 * Last changed in libpng 1.5.17 [July 18, 2013]
8 * This code is released under the libpng license.
9 * For conditions of distribution and use, see the disclaimer
10 * and license in png.h
12 /* Below, after checking __linux__, various non-C90 POSIX 1003.1 functions are
15 #define _POSIX_SOURCE 1
17 #include "../pngpriv.h"
19 #ifdef PNG_READ_SUPPORTED
20 if (((png_ptr->options >> PNG_MAXIMUM_INFLATE_WINDOW) & 3) ==
22 #if PNG_ARM_NEON_OPT > 0
23 #ifdef PNG_ARM_NEON_CHECK_SUPPORTED /* Do run-time checks */
24 #include <signal.h> /* for sig_atomic_t */
27 /* Linux provides access to information about CPU capabilites via
28 * /proc/self/auxv, however Android blocks this while still claiming to be
29 * Linux. The Andoid NDK, however, provides appropriate support.
31 * Documentation: http://www.kandroid.org/ndk/docs/CPU-ARM-NEON.html
33 #include <cpu-features.h>
36 png_have_neon(png_structp png_ptr)
38 /* This is a whole lot easier than the mess below, however it is probably
39 * implemented as below, therefore it is better to cache the result (these
40 * function calls may be slow!)
43 return android_getCpuFamily() == ANDROID_CPU_FAMILY_ARM &&
44 (android_getCpuFeatures() & ANDROID_CPU_ARM_FEATURE_NEON) != 0;
46 #elif defined(__linux__)
47 /* The generic __linux__ implementation requires reading /proc/self/auxv and
48 * looking at each element for one that records NEON capabilities.
50 #include <unistd.h> /* for POSIX 1003.1 */
51 #include <errno.h> /* for EINTR */
53 #include <sys/types.h>
57 #include <asm/hwcap.h>
59 /* A read call may be interrupted, in which case it returns -1 and sets errno to
60 * EINTR if nothing was done, otherwise (if something was done) a partial read
64 safe_read(png_structp png_ptr, int fd, void *buffer_in, size_t nbytes)
67 char *buffer = png_voidcast(char*, buffer_in);
74 /* Passing nread > INT_MAX to read is implementation defined in POSIX
75 * 1003.1, therefore despite the unsigned argument portable code must
76 * limit the value to INT_MAX!
82 nread = (unsigned int)/*SAFE*/nbytes;
84 iread = read(fd, buffer, nread);
88 /* This is the devil in the details, a read can terminate early with 0
89 * bytes read because of EINTR, yet it still returns -1 otherwise end
90 * of file cannot be distinguished.
94 png_warning(png_ptr, "/proc read failed");
95 return 0; /* I.e. a permanent failure */
101 /* Not a valid 'read' result: */
102 png_warning(png_ptr, "OS /proc read bug");
108 /* Continue reading until a permanent failure, or EOF */
110 nbytes -= (unsigned int)/*SAFE*/iread;
111 ntotal += (unsigned int)/*SAFE*/iread;
118 return ntotal; /* nbytes == 0 */
122 png_have_neon(png_structp png_ptr)
124 int fd = open("/proc/self/auxv", O_RDONLY);
127 /* Failsafe: failure to open means no NEON */
130 png_warning(png_ptr, "/proc/self/auxv open failed");
134 while (safe_read(png_ptr, fd, &aux, sizeof aux) == sizeof aux)
136 if (aux.a_type == AT_HWCAP && (aux.a_un.a_val & HWCAP_NEON) != 0)
147 /* We don't know how to do a run-time check on this system */
148 # error "no support for run-time ARM NEON checks"
149 #endif /* OS checks */
150 #endif /* PNG_ARM_NEON_CHECK_SUPPORTED */
152 #ifndef PNG_ALIGNED_MEMORY_SUPPORTED
153 # error "ALIGNED_MEMORY is required; set: -DPNG_ALIGNED_MEMORY_SUPPORTED"
157 png_init_filter_functions_neon(png_structp pp, unsigned int bpp)
159 #ifdef PNG_ARM_NEON_API_SUPPORTED
160 switch ((pp->options >> PNG_ARM_NEON) & 3)
162 case PNG_OPTION_UNSET:
163 /* Allow the run-time check to execute if it has been enabled -
164 * thus both API and CHECK can be turned on. If it isn't supported
165 * this case will fall through to the 'default' below, which just
168 #endif /* PNG_ARM_NEON_API_SUPPORTED */
169 #ifdef PNG_ARM_NEON_CHECK_SUPPORTED
171 static volatile sig_atomic_t no_neon = -1; /* not checked */
174 no_neon = !png_have_neon(pp);
179 #ifdef PNG_ARM_NEON_API_SUPPORTED
182 #endif /* PNG_ARM_NEON_CHECK_SUPPORTED */
183 #ifdef PNG_ARM_NEON_API_SUPPORTED
185 /* Option turned on */
188 default: /* OFF or INVALID */
193 /* IMPORTANT: any new external functions used here must be declared using
194 * PNG_INTERNAL_FUNCTION in ../pngpriv.h. This is required so that the
195 * 'prefix' option to configure works:
197 * ./configure --with-libpng-prefix=foobar_
199 * Verify you have got this right by running the above command, doing a build
200 * and examining pngprefix.h; it must contain a #define for every external
201 * function you add. (Notice that this happens automatically for the
202 * initialization function.)
204 pp->read_filter[PNG_FILTER_VALUE_UP-1] = png_read_filter_row_up_neon;
208 pp->read_filter[PNG_FILTER_VALUE_SUB-1] = png_read_filter_row_sub3_neon;
209 pp->read_filter[PNG_FILTER_VALUE_AVG-1] = png_read_filter_row_avg3_neon;
210 pp->read_filter[PNG_FILTER_VALUE_PAETH-1] =
211 png_read_filter_row_paeth3_neon;
216 pp->read_filter[PNG_FILTER_VALUE_SUB-1] = png_read_filter_row_sub4_neon;
217 pp->read_filter[PNG_FILTER_VALUE_AVG-1] = png_read_filter_row_avg4_neon;
218 pp->read_filter[PNG_FILTER_VALUE_PAETH-1] =
219 png_read_filter_row_paeth4_neon;
222 #endif /* PNG_ARM_NEON_OPT > 0 */
223 #endif /* PNG_READ_SUPPORTED */