1
2 /* arm_init.c - NEON optimised filter functions
3 *
4 * Copyright (c) 2014 Glenn Randers-Pehrson
5 * Written by Mans Rullgard, 2011.
6 * Last changed in libpng 1.6.16 [December 22, 2014]
7 *
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
11 */
12 /* Below, after checking __linux__, various non-C90 POSIX 1003.1 functions are
13 * called.
14 */
15 #define _POSIX_SOURCE 1
16
17 #include "../pngpriv.h"
18 #define PNG_SRC_FILE PNG_SRC_FILE_arm_arm_init
19
20 #ifdef PNG_READ_SUPPORTED
21
22 #if PNG_ARM_NEON_OPT > 0
23 #ifdef PNG_ARM_NEON_CHECK_SUPPORTED /* Do run-time checks */
24 /* WARNING: it is strongly recommended that you do not build libpng with
25 * run-time checks for CPU features if at all possible. In the case of the ARM
26 * NEON instructions there is no processor-specific way of detecting the
27 * presence of the required support, therefore run-time detection is extremely
28 * OS specific.
29 *
30 * You may set the macro PNG_ARM_NEON_FILE to the file name of file containing
31 * a fragment of C source code which defines the png_have_neon function. There
32 * are a number of implementations in contrib/arm-neon, but the only one that
33 * has partial support is contrib/arm-neon/linux.c - a generic Linux
34 * implementation which reads /proc/cpufino.
35 */
36 #ifndef PNG_ARM_NEON_FILE
37 # ifdef __linux__
38 # define PNG_ARM_NEON_FILE "contrib/arm-neon/linux.c"
39 # endif
40 #endif
41
42 #ifdef PNG_ARM_NEON_FILE
43
44 #include <signal.h> /* for sig_atomic_t */
45 static int png_have_neon(png_structp png_ptr);
46 #include PNG_ARM_NEON_FILE
47
48 #else /* PNG_ARM_NEON_FILE */
49 # error "PNG_ARM_NEON_FILE undefined: no support for run-time ARM NEON checks"
50 #endif /* PNG_ARM_NEON_FILE */
51 #endif /* PNG_ARM_NEON_CHECK_SUPPORTED */
52
53 #ifndef PNG_ALIGNED_MEMORY_SUPPORTED
54 # error "ALIGNED_MEMORY is required; set: -DPNG_ALIGNED_MEMORY_SUPPORTED"
55 #endif
56
57 void
png_init_filter_functions_neon(png_structp pp,unsigned int bpp)58 png_init_filter_functions_neon(png_structp pp, unsigned int bpp)
59 {
60 /* The switch statement is compiled in for ARM_NEON_API, the call to
61 * png_have_neon is compiled in for ARM_NEON_CHECK. If both are defined
62 * the check is only performed if the API has not set the NEON option on
63 * or off explicitly. In this case the check controls what happens.
64 *
65 * If the CHECK is not compiled in and the option is UNSET the behavior prior
66 * to 1.6.7 was to use the NEON code - this was a bug caused by having the
67 * wrong order of the 'ON' and 'default' cases. UNSET now defaults to OFF,
68 * as documented in png.h
69 */
70 #ifdef PNG_ARM_NEON_API_SUPPORTED
71 switch ((pp->options >> PNG_ARM_NEON) & 3)
72 {
73 case PNG_OPTION_UNSET:
74 /* Allow the run-time check to execute if it has been enabled -
75 * thus both API and CHECK can be turned on. If it isn't supported
76 * this case will fall through to the 'default' below, which just
77 * returns.
78 */
79 #endif /* PNG_ARM_NEON_API_SUPPORTED */
80 #ifdef PNG_ARM_NEON_CHECK_SUPPORTED
81 {
82 static volatile sig_atomic_t no_neon = -1; /* not checked */
83
84 if (no_neon < 0)
85 no_neon = !png_have_neon(pp);
86
87 if (no_neon)
88 return;
89 }
90 #ifdef PNG_ARM_NEON_API_SUPPORTED
91 break;
92 #endif
93 #endif /* PNG_ARM_NEON_CHECK_SUPPORTED */
94
95 #ifdef PNG_ARM_NEON_API_SUPPORTED
96 default: /* OFF or INVALID */
97 return;
98
99 case PNG_OPTION_ON:
100 /* Option turned on */
101 break;
102 }
103 #endif
104
105 /* IMPORTANT: any new external functions used here must be declared using
106 * PNG_INTERNAL_FUNCTION in ../pngpriv.h. This is required so that the
107 * 'prefix' option to configure works:
108 *
109 * ./configure --with-libpng-prefix=foobar_
110 *
111 * Verify you have got this right by running the above command, doing a build
112 * and examining pngprefix.h; it must contain a #define for every external
113 * function you add. (Notice that this happens automatically for the
114 * initialization function.)
115 */
116 pp->read_filter[PNG_FILTER_VALUE_UP-1] = png_read_filter_row_up_neon;
117
118 if (bpp == 3)
119 {
120 pp->read_filter[PNG_FILTER_VALUE_SUB-1] = png_read_filter_row_sub3_neon;
121 pp->read_filter[PNG_FILTER_VALUE_AVG-1] = png_read_filter_row_avg3_neon;
122 pp->read_filter[PNG_FILTER_VALUE_PAETH-1] =
123 png_read_filter_row_paeth3_neon;
124 }
125
126 else if (bpp == 4)
127 {
128 pp->read_filter[PNG_FILTER_VALUE_SUB-1] = png_read_filter_row_sub4_neon;
129 pp->read_filter[PNG_FILTER_VALUE_AVG-1] = png_read_filter_row_avg4_neon;
130 pp->read_filter[PNG_FILTER_VALUE_PAETH-1] =
131 png_read_filter_row_paeth4_neon;
132 }
133 }
134 #endif /* PNG_ARM_NEON_OPT > 0 */
135 #endif /* READ */
136