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FFmpeg/libavutil/arm/cpu.c
Martin Storsjö ab8f1a6989 arm: Fall back to runtime cpu feature detection via /proc/cpuinfo
On recent android versions, /proc/self/auxw is unreadable
(unless the process is running running under the shell uid or
in debuggable mode, which makes it hard to notice). See
http://b.android.com/43055 and
https://android-review.googlesource.com/51271 for more information
about the issue.

This makes sure e.g. neon optimizations are enabled at runtime in
android apps even when built in release mode, if configured to
use the runtime detection.

CC: libav-stable@libav.org
Signed-off-by: Martin Storsjö <martin@martin.st>
2013-02-11 17:15:15 +02:00

147 lines
4.0 KiB
C

/*
* This file is part of Libav.
*
* Libav is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* Libav is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with Libav; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include "libavutil/cpu.h"
#include "config.h"
#define CORE_FLAG(f) \
(AV_CPU_FLAG_ ## f * (HAVE_ ## f ## _EXTERNAL || HAVE_ ## f ## _INLINE))
#define CORE_CPU_FLAGS \
(CORE_FLAG(ARMV5TE) | \
CORE_FLAG(ARMV6) | \
CORE_FLAG(ARMV6T2) | \
CORE_FLAG(VFP) | \
CORE_FLAG(VFPV3) | \
CORE_FLAG(NEON))
#if defined __linux__ || defined __ANDROID__
#include <stdint.h>
#include <stdio.h>
#include <string.h>
#include "libavutil/avstring.h"
#define AT_HWCAP 16
/* Relevant HWCAP values from kernel headers */
#define HWCAP_VFP (1 << 6)
#define HWCAP_EDSP (1 << 7)
#define HWCAP_THUMBEE (1 << 11)
#define HWCAP_NEON (1 << 12)
#define HWCAP_VFPv3 (1 << 13)
#define HWCAP_TLS (1 << 15)
static int get_hwcap(uint32_t *hwcap)
{
struct { uint32_t a_type; uint32_t a_val; } auxv;
FILE *f = fopen("/proc/self/auxv", "r");
int err = -1;
if (!f)
return -1;
while (fread(&auxv, sizeof(auxv), 1, f) > 0) {
if (auxv.a_type == AT_HWCAP) {
*hwcap = auxv.a_val;
err = 0;
break;
}
}
fclose(f);
return err;
}
static int get_cpuinfo(uint32_t *hwcap)
{
FILE *f = fopen("/proc/cpuinfo", "r");
char buf[200];
if (!f)
return -1;
*hwcap = 0;
while (fgets(buf, sizeof(buf), f)) {
if (av_strstart(buf, "Features", NULL)) {
if (strstr(buf, " edsp "))
*hwcap |= HWCAP_EDSP;
if (strstr(buf, " tls "))
*hwcap |= HWCAP_TLS;
if (strstr(buf, " thumbee "))
*hwcap |= HWCAP_THUMBEE;
if (strstr(buf, " vfp "))
*hwcap |= HWCAP_VFP;
if (strstr(buf, " vfpv3 "))
*hwcap |= HWCAP_VFPv3;
if (strstr(buf, " neon "))
*hwcap |= HWCAP_NEON;
break;
}
}
fclose(f);
return 0;
}
int ff_get_cpu_flags_arm(void)
{
int flags = CORE_CPU_FLAGS;
uint32_t hwcap;
if (get_hwcap(&hwcap) < 0)
if (get_cpuinfo(&hwcap) < 0)
return flags;
#define check_cap(cap, flag) do { \
if (hwcap & HWCAP_ ## cap) \
flags |= AV_CPU_FLAG_ ## flag; \
} while (0)
/* No flags explicitly indicate v6 or v6T2 so check others which
imply support. */
check_cap(EDSP, ARMV5TE);
check_cap(TLS, ARMV6);
check_cap(THUMBEE, ARMV6T2);
check_cap(VFP, VFP);
check_cap(VFPv3, VFPV3);
check_cap(NEON, NEON);
/* The v6 checks above are not reliable so let higher flags
trickle down. */
if (flags & (AV_CPU_FLAG_VFPV3 | AV_CPU_FLAG_NEON))
flags |= AV_CPU_FLAG_ARMV6T2;
if (flags & AV_CPU_FLAG_ARMV6T2)
flags |= AV_CPU_FLAG_ARMV6;
return flags;
}
#else
int ff_get_cpu_flags_arm(void)
{
return AV_CPU_FLAG_ARMV5TE * HAVE_ARMV5TE |
AV_CPU_FLAG_ARMV6 * HAVE_ARMV6 |
AV_CPU_FLAG_ARMV6T2 * HAVE_ARMV6T2 |
AV_CPU_FLAG_VFP * HAVE_VFP |
AV_CPU_FLAG_VFPV3 * HAVE_VFPV3 |
AV_CPU_FLAG_NEON * HAVE_NEON;
}
#endif