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cpu.c
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1 /*
2  * This file is part of FFmpeg.
3  *
4  * FFmpeg is free software; you can redistribute it and/or
5  * modify it under the terms of the GNU Lesser General Public
6  * License as published by the Free Software Foundation; either
7  * version 2.1 of the License, or (at your option) any later version.
8  *
9  * FFmpeg is distributed in the hope that it will be useful,
10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
12  * Lesser General Public License for more details.
13  *
14  * You should have received a copy of the GNU Lesser General Public
15  * License along with FFmpeg; if not, write to the Free Software
16  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
17  */
18 
19 #include "libavutil/cpu.h"
20 #include "libavutil/cpu_internal.h"
21 #include "config.h"
22 
23 #define CORE_FLAG(f) \
24  (AV_CPU_FLAG_ ## f * (HAVE_ ## f ## _EXTERNAL || HAVE_ ## f ## _INLINE))
25 
26 #define CORE_CPU_FLAGS \
27  (CORE_FLAG(ARMV5TE) | \
28  CORE_FLAG(ARMV6) | \
29  CORE_FLAG(ARMV6T2) | \
30  CORE_FLAG(VFP) | \
31  CORE_FLAG(VFPV3) | \
32  CORE_FLAG(NEON))
33 
34 #if defined __linux__ || defined __ANDROID__
35 
36 #include <stdint.h>
37 #include <stdio.h>
38 #include <string.h>
39 #include "libavutil/avstring.h"
40 
41 #define AT_HWCAP 16
42 
43 /* Relevant HWCAP values from kernel headers */
44 #define HWCAP_VFP (1 << 6)
45 #define HWCAP_EDSP (1 << 7)
46 #define HWCAP_THUMBEE (1 << 11)
47 #define HWCAP_NEON (1 << 12)
48 #define HWCAP_VFPv3 (1 << 13)
49 #define HWCAP_TLS (1 << 15)
50 
51 static int get_hwcap(uint32_t *hwcap)
52 {
53  struct { uint32_t a_type; uint32_t a_val; } auxv;
54  FILE *f = fopen("/proc/self/auxv", "r");
55  int err = -1;
56 
57  if (!f)
58  return -1;
59 
60  while (fread(&auxv, sizeof(auxv), 1, f) > 0) {
61  if (auxv.a_type == AT_HWCAP) {
62  *hwcap = auxv.a_val;
63  err = 0;
64  break;
65  }
66  }
67 
68  fclose(f);
69  return err;
70 }
71 
72 static int get_cpuinfo(uint32_t *hwcap)
73 {
74  FILE *f = fopen("/proc/cpuinfo", "r");
75  char buf[200];
76 
77  if (!f)
78  return -1;
79 
80  *hwcap = 0;
81  while (fgets(buf, sizeof(buf), f)) {
82  if (av_strstart(buf, "Features", NULL)) {
83  if (strstr(buf, " edsp "))
84  *hwcap |= HWCAP_EDSP;
85  if (strstr(buf, " tls "))
86  *hwcap |= HWCAP_TLS;
87  if (strstr(buf, " thumbee "))
88  *hwcap |= HWCAP_THUMBEE;
89  if (strstr(buf, " vfp "))
90  *hwcap |= HWCAP_VFP;
91  if (strstr(buf, " vfpv3 "))
92  *hwcap |= HWCAP_VFPv3;
93  if (strstr(buf, " neon "))
94  *hwcap |= HWCAP_NEON;
95  break;
96  }
97  }
98  fclose(f);
99  return 0;
100 }
101 
102 int ff_get_cpu_flags_arm(void)
103 {
104  int flags = CORE_CPU_FLAGS;
105  uint32_t hwcap;
106 
107  if (get_hwcap(&hwcap) < 0)
108  if (get_cpuinfo(&hwcap) < 0)
109  return flags;
110 
111 #define check_cap(cap, flag) do { \
112  if (hwcap & HWCAP_ ## cap) \
113  flags |= AV_CPU_FLAG_ ## flag; \
114  } while (0)
115 
116  /* No flags explicitly indicate v6 or v6T2 so check others which
117  imply support. */
118  check_cap(EDSP, ARMV5TE);
119  check_cap(TLS, ARMV6);
120  check_cap(THUMBEE, ARMV6T2);
121  check_cap(VFP, VFP);
122  check_cap(VFPv3, VFPV3);
123  check_cap(NEON, NEON);
124 
125  /* The v6 checks above are not reliable so let higher flags
126  trickle down. */
127  if (flags & (AV_CPU_FLAG_VFPV3 | AV_CPU_FLAG_NEON))
128  flags |= AV_CPU_FLAG_ARMV6T2;
129  if (flags & AV_CPU_FLAG_ARMV6T2)
130  flags |= AV_CPU_FLAG_ARMV6;
131 
132  return flags;
133 }
134 
135 #else
136 
138 {
139  return AV_CPU_FLAG_ARMV5TE * HAVE_ARMV5TE |
140  AV_CPU_FLAG_ARMV6 * HAVE_ARMV6 |
141  AV_CPU_FLAG_ARMV6T2 * HAVE_ARMV6T2 |
142  AV_CPU_FLAG_VFP * HAVE_VFP |
143  AV_CPU_FLAG_VFPV3 * HAVE_VFPV3 |
144  AV_CPU_FLAG_NEON * HAVE_NEON;
145 }
146 
147 #endif