ffmpeg/libavutil/arm/cpu.c
Janne Grunau e2710e790c arm: add a cpu flag for the VFPv2 vector mode
The vector mode was deprecated in ARMv7-A/VFPv3 and various cpu
implementations do not support it in hardware. Vector mode code will
depending the OS either be emulated in software or result in an illegal
instruction on cpus which does not support it. This was not really
problem in practice since NEON implementations of the same functions are
preferred. It will however become a problem for checkasm which tests
every cpu flag separately.

Since this is a cpu feature newer cpu do not support anymore the
behaviour of this flag differs from the other flags. It can be only
activated by runtime cpu feature selection.
2015-12-14 16:42:35 +01:00

154 lines
4.3 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 "libavutil/cpu_internal.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 ") || strstr(buf, " asimd "))
*hwcap |= HWCAP_NEON;
if (strstr(buf, " fp ")) // Listed on 64 bit ARMv8 kernels
*hwcap |= HWCAP_VFP | HWCAP_VFPv3;
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;
/* set the virtual VFPv2 vector mode flag */
if ((flags & AV_CPU_FLAG_VFP) && !(flags & (AV_CPU_FLAG_VFPV3 | AV_CPU_FLAG_NEON)))
flags |= AV_CPU_FLAG_VFP_VM;
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