1 files changed, 90 insertions, 0 deletions
diff --git a/vpx_ports/aarch32_cpudetect.c b/vpx_ports/aarch32_cpudetect.c
new file mode 100644
index 000000000..639f4ff8e
--- /dev/null
+++ b/vpx_ports/aarch32_cpudetect.c
@@ -0,0 +1,90 @@
+/*
+ *  Copyright (c) 2023 The WebM project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+// Feature detection code for Armv7-A / AArch32.
+
+#include "./vpx_config.h"
+#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 || HAVE_NEON_ASM
+  // 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 || HAVE_NEON_ASM
+  return flags;
+}
+
+#elif defined(ANDROID_USE_CPU_FEATURES_LIB)
+
+static int arm_get_cpu_caps(void) {
+  int flags = 0;
+#if HAVE_NEON || HAVE_NEON_ASM
+  uint64_t features = android_getCpuFeatures();
+  if (features & ANDROID_CPU_ARM_FEATURE_NEON) {
+    flags |= HAS_NEON;
+  }
+#endif  // HAVE_NEON || HAVE_NEON_ASM
+  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 VPX_AARCH32_HWCAP_NEON (1 << 12)
+
+static int arm_get_cpu_caps(void) {
+  int flags = 0;
+  unsigned long hwcap = getauxval(AT_HWCAP);
+#if HAVE_NEON || HAVE_NEON_ASM
+  if (hwcap & VPX_AARCH32_HWCAP_NEON) {
+    flags |= HAS_NEON;
+  }
+#endif  // HAVE_NEON || HAVE_NEON_ASM
+  return flags;
+}
+#else   // end __linux__
+#error \
+    "Runtime CPU detection selected, but no CPU detection method available" \
+"for your platform. Rerun configure with --disable-runtime-cpu-detect."
+#endif
+
+int arm_cpu_caps(void) {
+  int flags = 0;
+  if (arm_cpu_env_flags(&flags)) {
+    return flags;
+  }
+  return arm_get_cpu_caps() & arm_cpu_env_mask();
+}