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/*
* Copyright (c) 2023, Alliance for Open Media. All rights reserved
*
* This source code is subject to the terms of the BSD 2 Clause License and
* the Alliance for Open Media Patent License 1.0. If the BSD 2 Clause License
* was not distributed with this source code in the LICENSE file, you can
* obtain it at www.aomedia.org/license/software. If the Alliance for Open
* Media Patent License 1.0 was not distributed with this source code in the
* PATENTS file, you can obtain it at www.aomedia.org/license/patent.
*/
// Feature detection code for Armv7-A / AArch32.
#include "arm_cpudetect.h"
#if !CONFIG_RUNTIME_CPU_DETECT
static int arm_get_cpu_caps(void) {
// This function should actually be a no-op. There is no way to adjust any of
// these because the RTCD tables do not exist: the functions are called
// statically.
int flags = 0;
#if HAVE_NEON
flags |= HAS_NEON;
#endif // HAVE_NEON
return flags;
}
#elif defined(_MSC_VER) // end !CONFIG_RUNTIME_CPU_DETECT
static int arm_get_cpu_caps(void) {
int flags = 0;
#if HAVE_NEON
// MSVC has no inline __asm support for Arm, but it does let you __emit
// instructions via their assembled hex code.
// All of these instructions should be essentially nops.
__try {
// VORR q0,q0,q0
__emit(0xF2200150);
flags |= HAS_NEON;
} __except (GetExceptionCode() == EXCEPTION_ILLEGAL_INSTRUCTION) {
// Ignore exception.
}
#endif // HAVE_NEON
return flags;
}
#elif defined(ANDROID_USE_CPU_FEATURES_LIB)
static int arm_get_cpu_caps(void) {
int flags = 0;
#if HAVE_NEON
uint64_t features = android_getCpuFeatures();
if (features & ANDROID_CPU_ARM_FEATURE_NEON) flags |= HAS_NEON;
#endif // HAVE_NEON
return flags;
}
#elif defined(__linux__) // end defined(AOM_USE_ANDROID_CPU_FEATURES)
#include <sys/auxv.h>
// Define hwcap values ourselves: building with an old auxv header where these
// hwcap values are not defined should not prevent features from being enabled.
#define AOM_AARCH32_HWCAP_NEON (1 << 12)
static int arm_get_cpu_caps(void) {
int flags = 0;
unsigned long hwcap = getauxval(AT_HWCAP);
#if HAVE_NEON
if (hwcap & AOM_AARCH32_HWCAP_NEON) flags |= HAS_NEON;
#endif // HAVE_NEON
return flags;
}
#else // end __linux__
#error \
"Runtime CPU detection selected, but no CPU detection method " \
"available for your platform. Rerun cmake with -DCONFIG_RUNTIME_CPU_DETECT=0."
#endif
int aom_arm_cpu_caps(void) {
int flags = 0;
if (arm_cpu_env_flags(&flags)) {
return flags;
}
return arm_get_cpu_caps() & arm_cpu_env_mask();
}
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