1 files changed, 84 insertions, 0 deletions
diff --git a/src/utils/cpu.cc b/src/utils/cpu.cc
new file mode 100644
index 0000000..a6b7057
--- /dev/null
+++ b/src/utils/cpu.cc
@@ -0,0 +1,84 @@
+// Copyright 2019 The libgav1 Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include "src/utils/cpu.h"
+
+#if defined(__GNUC__) && (defined(__i386__) || defined(__x86_64__))
+#include <cpuid.h>
+#elif defined(_MSC_VER) && (defined(_M_IX86) || defined(_M_X64))
+#include <immintrin.h>  // _xgetbv
+#include <intrin.h>
+#endif
+
+namespace libgav1 {
+
+#if defined(__i386__) || defined(__x86_64__) || defined(_M_IX86) || \
+    defined(_M_X64)
+namespace {
+
+#if defined(__GNUC__)
+void CpuId(int leaf, uint32_t info[4]) {
+  __cpuid_count(leaf, 0 /*ecx=subleaf*/, info[0], info[1], info[2], info[3]);
+}
+
+uint64_t Xgetbv() {
+  const uint32_t ecx = 0;  // ecx specifies the extended control register
+  uint32_t eax;
+  uint32_t edx;
+  __asm__ volatile("xgetbv" : "=a"(eax), "=d"(edx) : "c"(ecx));
+  return (static_cast<uint64_t>(edx) << 32) | eax;
+}
+#else  // _MSC_VER
+void CpuId(int leaf, uint32_t info[4]) {
+  __cpuidex(reinterpret_cast<int*>(info), leaf, 0 /*ecx=subleaf*/);
+}
+
+uint64_t Xgetbv() { return _xgetbv(0); }
+#endif  // __GNUC__
+
+}  // namespace
+
+uint32_t GetCpuInfo() {
+  uint32_t info[4];
+
+  // Get the highest feature value cpuid supports
+  CpuId(0, info);
+  const int max_cpuid_value = info[0];
+  if (max_cpuid_value < 1) return 0;
+
+  CpuId(1, info);
+  uint32_t features = 0;
+  if ((info[3] & (1 << 26)) != 0) features |= kSSE2;
+  if ((info[2] & (1 << 9)) != 0) features |= kSSSE3;
+  if ((info[2] & (1 << 19)) != 0) features |= kSSE4_1;
+
+  // Bits 27 (OSXSAVE) & 28 (256-bit AVX)
+  if ((info[2] & (3 << 27)) == (3 << 27)) {
+    // XMM state and YMM state enabled by the OS
+    if ((Xgetbv() & 0x6) == 0x6) {
+      features |= kAVX;
+      if (max_cpuid_value >= 7) {
+        CpuId(7, info);
+        if ((info[1] & (1 << 5)) != 0) features |= kAVX2;
+      }
+    }
+  }
+
+  return features;
+}
+#else
+uint32_t GetCpuInfo() { return 0; }
+#endif  // x86 || x86_64
+
+}  // namespace libgav1