opencv

1

2
/* arm_init.c - NEON optimised filter functions
3
 *
4
 * Copyright (c) 2018-2022 Cosmin Truta
5
 * Copyright (c) 2014,2016 Glenn Randers-Pehrson
6
 * Written by Mans Rullgard, 2011.
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

13
/* This module requires POSIX 1003.1 functions. */
14
#define _POSIX_SOURCE 1
15

16
#include "../pngpriv.h"
17

18
#ifdef PNG_READ_SUPPORTED
19

20
#if PNG_ARM_NEON_OPT > 0
21
#ifdef PNG_ARM_NEON_CHECK_SUPPORTED /* Do run-time checks */
22
/* WARNING: it is strongly recommended that you do not build libpng with
23
 * run-time checks for CPU features if at all possible.  In the case of the ARM
24
 * NEON instructions there is no processor-specific way of detecting the
25
 * presence of the required support, therefore run-time detection is extremely
26
 * OS specific.
27
 *
28
 * You may set the macro PNG_ARM_NEON_FILE to the file name of file containing
29
 * a fragment of C source code which defines the png_have_neon function.  There
30
 * are a number of implementations in contrib/arm-neon, but the only one that
31
 * has partial support is contrib/arm-neon/linux.c - a generic Linux
32
 * implementation which reads /proc/cpufino.
33
 */
34
#include <signal.h> /* for sig_atomic_t */
35

36
#ifndef PNG_ARM_NEON_FILE
37
#  if defined(__aarch64__) || defined(_M_ARM64)
38
     /* ARM Neon is expected to be unconditionally available on ARM64. */
39
#    error "PNG_ARM_NEON_CHECK_SUPPORTED must not be defined on ARM64"
40
#  elif defined(__ARM_NEON__) || defined(__ARM_NEON)
41
     /* ARM Neon is expected to be available on the target CPU architecture. */
42
#    error "PNG_ARM_NEON_CHECK_SUPPORTED must not be defined on this CPU arch"
43
#  elif defined(__linux__)
44
#    define PNG_ARM_NEON_FILE "contrib/arm-neon/linux.c"
45
#  else
46
#    error "No support for run-time ARM Neon checking; use compile-time options"
47
#  endif
48
#endif
49

50
static int png_have_neon(png_structp png_ptr);
51
#ifdef PNG_ARM_NEON_FILE
52
#  include PNG_ARM_NEON_FILE
53
#endif
54
#endif /* PNG_ARM_NEON_CHECK_SUPPORTED */
55

56
#ifndef PNG_ALIGNED_MEMORY_SUPPORTED
57
#  error "ALIGNED_MEMORY is required; set: -DPNG_ALIGNED_MEMORY_SUPPORTED"
58
#endif
59

60
void
61
png_init_filter_functions_neon(png_structp pp, unsigned int bpp)
62
{
63
   /* The switch statement is compiled in for ARM_NEON_API, the call to
64
    * png_have_neon is compiled in for ARM_NEON_CHECK.  If both are defined
65
    * the check is only performed if the API has not set the NEON option on
66
    * or off explicitly.  In this case the check controls what happens.
67
    *
68
    * If the CHECK is not compiled in and the option is UNSET the behavior prior
69
    * to 1.6.7 was to use the NEON code - this was a bug caused by having the
70
    * wrong order of the 'ON' and 'default' cases.  UNSET now defaults to OFF,
71
    * as documented in png.h
72
    */
73
   png_debug(1, "in png_init_filter_functions_neon");
74
#ifdef PNG_ARM_NEON_API_SUPPORTED
75
   switch ((pp->options >> PNG_ARM_NEON) & 3)
76
   {
77
      case PNG_OPTION_UNSET:
78
         /* Allow the run-time check to execute if it has been enabled -
79
          * thus both API and CHECK can be turned on.  If it isn't supported
80
          * this case will fall through to the 'default' below, which just
81
          * returns.
82
          */
83
#endif /* PNG_ARM_NEON_API_SUPPORTED */
84
#ifdef PNG_ARM_NEON_CHECK_SUPPORTED
85
         {
86
            static volatile sig_atomic_t no_neon = -1; /* not checked */
87

88
            if (no_neon < 0)
89
               no_neon = !png_have_neon(pp);
90

91
            if (no_neon)
92
               return;
93
         }
94
#ifdef PNG_ARM_NEON_API_SUPPORTED
95
         break;
96
#endif
97
#endif /* PNG_ARM_NEON_CHECK_SUPPORTED */
98

99
#ifdef PNG_ARM_NEON_API_SUPPORTED
100
      default: /* OFF or INVALID */
101
         return;
102

103
      case PNG_OPTION_ON:
104
         /* Option turned on */
105
         break;
106
   }
107
#endif
108

109
   /* IMPORTANT: any new external functions used here must be declared using
110
    * PNG_INTERNAL_FUNCTION in ../pngpriv.h.  This is required so that the
111
    * 'prefix' option to configure works:
112
    *
113
    *    ./configure --with-libpng-prefix=foobar_
114
    *
115
    * Verify you have got this right by running the above command, doing a build
116
    * and examining pngprefix.h; it must contain a #define for every external
117
    * function you add.  (Notice that this happens automatically for the
118
    * initialization function.)
119
    */
120
   pp->read_filter[PNG_FILTER_VALUE_UP-1] = png_read_filter_row_up_neon;
121

122
   if (bpp == 3)
123
   {
124
      pp->read_filter[PNG_FILTER_VALUE_SUB-1] = png_read_filter_row_sub3_neon;
125
      pp->read_filter[PNG_FILTER_VALUE_AVG-1] = png_read_filter_row_avg3_neon;
126
      pp->read_filter[PNG_FILTER_VALUE_PAETH-1] =
127
         png_read_filter_row_paeth3_neon;
128
   }
129

130
   else if (bpp == 4)
131
   {
132
      pp->read_filter[PNG_FILTER_VALUE_SUB-1] = png_read_filter_row_sub4_neon;
133
      pp->read_filter[PNG_FILTER_VALUE_AVG-1] = png_read_filter_row_avg4_neon;
134
      pp->read_filter[PNG_FILTER_VALUE_PAETH-1] =
135
          png_read_filter_row_paeth4_neon;
136
   }
137
}
138
#endif /* PNG_ARM_NEON_OPT > 0 */
139
#endif /* READ */
140