Split AudioRendererMixer::VectorFMAC into VectorMath library.

media/base/vector_math.cc

+// Copyright (c) 2012 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "media/base/vector_math.h"
+
+#include "base/cpu.h"
+#include "base/logging.h"
+#include "build/build_config.h"
+
+#if defined(ARCH_CPU_X86_FAMILY) && defined(__SSE__)
+#include <xmmintrin.h>
+#endif
+
+namespace media {
+
+void VectorMath::FMAC(const float src[], float scale, int len, float dest[]) {
+  // Rely on function level static initialization to keep VectorFMACProc
+  // selection thread safe.
+  typedef void (*VectorFMACProc)(const float src[], float scale, int len,
+                                 float dest[]);
+#if defined(ARCH_CPU_X86_FAMILY) && defined(__SSE__)
+  static const VectorFMACProc kVectorFMACProc =
+      base::CPU().has_sse() ? FMAC_SSE : FMAC_C;
+#else
+  static const VectorFMACProc kVectorFMACProc = FMAC_C;
+#endif
+
+  return kVectorFMACProc(src, scale, len, dest);
+}
+
+void VectorMath::FMAC_C(const float src[], float scale, int len,
+                                      float dest[]) {
+  for (int i = 0; i < len; ++i)
+    dest[i] += src[i] * scale;
+}
+
+#if defined(ARCH_CPU_X86_FAMILY) && defined(__SSE__)
+void VectorMath::FMAC_SSE(const float src[], float scale, int len,
+                                        float dest[]) {
+  // Ensure |src| and |dest| are 16-byte aligned.
+  DCHECK_EQ(0u, reinterpret_cast<uintptr_t>(src) & 0x0F);
+  DCHECK_EQ(0u, reinterpret_cast<uintptr_t>(dest) & 0x0F);

[Ami GONE FROM CHROMIUM, 2012/08/23 17:28:12]

Do these checks belong in FMAC() instead of here?

[DaleCurtis, 2012/08/23 19:59:54]

Technically no, but since CPU selection is done at run time, it's probably safer
to put them there. As a bonus it allows testing without the branding=Chrome
flag. Done.

+
+  __m128 m_scale = _mm_set_ps1(scale);
+  int rem = len % 4;
+  for (int i = 0; i < len - rem; i += 4) {
+    _mm_store_ps(dest + i, _mm_add_ps(_mm_load_ps(dest + i),
+                 _mm_mul_ps(_mm_load_ps(src + i), m_scale)));
+  }
+
+  // Handle any remaining values that wouldn't fit in an SSE pass.
+  if (rem)
+    FMAC_C(src + len - rem, scale, rem, dest + len - rem);
+}
+#endif
+
+}  // namespace media