1 files changed, 86 insertions, 0 deletions
diff --git a/third_party/aom/aom_ports/aarch32_cpudetect.c b/third_party/aom/aom_ports/aarch32_cpudetect.c
new file mode 100644
index 0000000000..753f957112
--- /dev/null
+++ b/third_party/aom/aom_ports/aarch32_cpudetect.c
@@ -0,0 +1,86 @@
+/*
+ * 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();
+}