cpu.c

   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 ") || strstr(buf, " asimd "))
  94                 *hwcap |= HWCAP_NEON;
  95             if (strstr(buf, " fp ")) // Listed on 64 bit ARMv8 kernels
  96                 *hwcap |= HWCAP_VFP | HWCAP_VFPv3;
  97             break;
  98         }
  99     }
 100     fclose(f);
 101     return 0;
 102 }
 103
 104 int ff_get_cpu_flags_arm(void)
 105 {
 106     int flags = CORE_CPU_FLAGS;
 107     uint32_t hwcap;
 108
 109     if (get_hwcap(&hwcap) < 0)
 110         if (get_cpuinfo(&hwcap) < 0)
 111             return flags;
 112
 113 #define check_cap(cap, flag) do {               \
 114         if (hwcap & HWCAP_ ## cap)              \
 115             flags |= AV_CPU_FLAG_ ## flag;      \
 116     } while (0)
 117
 118     /* No flags explicitly indicate v6 or v6T2 so check others which
 119        imply support. */
 120     check_cap(EDSP,    ARMV5TE);
 121     check_cap(TLS,     ARMV6);
 122     check_cap(THUMBEE, ARMV6T2);
 123     check_cap(VFP,     VFP);
 124     check_cap(VFPv3,   VFPV3);
 125     check_cap(NEON,    NEON);
 126
 127     /* The v6 checks above are not reliable so let higher flags
 128        trickle down. */
 129     if (flags & (AV_CPU_FLAG_VFPV3 | AV_CPU_FLAG_NEON))
 130         flags |= AV_CPU_FLAG_ARMV6T2;
 131     else
 132     /* Some functions use the 'setend' instruction which is deprecated on ARMv8
 133      * and serializing on some ARMv7 cores. This ensures such functions
 134      * are only enabled on ARMv6. */
 135         flags |= AV_CPU_FLAG_SETEND;
 136
 137     if (flags & AV_CPU_FLAG_ARMV6T2)
 138         flags |= AV_CPU_FLAG_ARMV6;
 139
 140     return flags;
 141 }
 142
 143 #else
 144
 145 int ff_get_cpu_flags_arm(void)
 146 {
 147     return AV_CPU_FLAG_ARMV5TE * HAVE_ARMV5TE |
 148            AV_CPU_FLAG_ARMV6   * HAVE_ARMV6   |
 149            AV_CPU_FLAG_ARMV6T2 * HAVE_ARMV6T2 |
 150            AV_CPU_FLAG_VFP     * HAVE_VFP     |
 151            AV_CPU_FLAG_VFPV3   * HAVE_VFPV3   |
 152            AV_CPU_FLAG_NEON    * HAVE_NEON    |
 153            AV_CPU_FLAG_SETEND  * !(HAVE_NEON | HAVE_VFPV3);
 154 }
 155
 156 #endif