1 files changed, 109 insertions, 0 deletions
diff --git a/src/dsp/super_res.cc b/src/dsp/super_res.cc
new file mode 100644
index 0000000..d041bd1
--- /dev/null
+++ b/src/dsp/super_res.cc
@@ -0,0 +1,109 @@
+// Copyright 2020 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/dsp/super_res.h"
+
+#include <cassert>
+
+#include "src/dsp/dsp.h"
+#include "src/utils/common.h"
+#include "src/utils/constants.h"
+
+namespace libgav1 {
+namespace dsp {
+namespace {
+
+template <int bitdepth, typename Pixel>
+void SuperRes_C(const void* /*coefficients*/, void* const source,
+                const ptrdiff_t stride, const int height,
+                const int downscaled_width, const int upscaled_width,
+                const int initial_subpixel_x, const int step,
+                void* const dest) {
+  assert(step <= 1 << kSuperResScaleBits);
+  auto* src = static_cast<Pixel*>(source) - DivideBy2(kSuperResFilterTaps);
+  auto* dst = static_cast<Pixel*>(dest);
+  int y = height;
+  do {
+    ExtendLine<Pixel>(src + DivideBy2(kSuperResFilterTaps), downscaled_width,
+                      kSuperResHorizontalBorder, kSuperResHorizontalBorder);
+    // If (original) upscaled_width is <= 9, the downscaled_width may be
+    // upscaled_width - 1 (i.e. 8, 9), and become the same (i.e. 4) when
+    // subsampled via RightShiftWithRounding. This leads to an edge case where
+    // |step| == 1 << 14.
+    int subpixel_x = initial_subpixel_x;
+    int x = 0;
+    do {
+      int sum = 0;
+      const Pixel* const src_x = &src[subpixel_x >> kSuperResScaleBits];
+      const int src_x_subpixel =
+          (subpixel_x & kSuperResScaleMask) >> kSuperResExtraBits;
+      // The sign of each tap is: - + - + + - + -
+      sum -= src_x[0] * kUpscaleFilterUnsigned[src_x_subpixel][0];
+      sum += src_x[1] * kUpscaleFilterUnsigned[src_x_subpixel][1];
+      sum -= src_x[2] * kUpscaleFilterUnsigned[src_x_subpixel][2];
+      sum += src_x[3] * kUpscaleFilterUnsigned[src_x_subpixel][3];
+      sum += src_x[4] * kUpscaleFilterUnsigned[src_x_subpixel][4];
+      sum -= src_x[5] * kUpscaleFilterUnsigned[src_x_subpixel][5];
+      sum += src_x[6] * kUpscaleFilterUnsigned[src_x_subpixel][6];
+      sum -= src_x[7] * kUpscaleFilterUnsigned[src_x_subpixel][7];
+      dst[x] = Clip3(RightShiftWithRounding(sum, kFilterBits), 0,
+                     (1 << bitdepth) - 1);
+      subpixel_x += step;
+    } while (++x < upscaled_width);
+    src += stride;
+    dst += stride;
+  } while (--y != 0);
+}
+
+void Init8bpp() {
+  Dsp* dsp = dsp_internal::GetWritableDspTable(8);
+  assert(dsp != nullptr);
+  dsp->super_res_coefficients = nullptr;
+#if LIBGAV1_ENABLE_ALL_DSP_FUNCTIONS
+  dsp->super_res = SuperRes_C<8, uint8_t>;
+#else  // !LIBGAV1_ENABLE_ALL_DSP_FUNCTIONS
+  static_cast<void>(dsp);
+#ifndef LIBGAV1_Dsp8bpp_SuperRes
+  dsp->super_res = SuperRes_C<8, uint8_t>;
+#endif
+#endif  // LIBGAV1_ENABLE_ALL_DSP_FUNCTIONS
+}
+
+#if LIBGAV1_MAX_BITDEPTH >= 10
+void Init10bpp() {
+  Dsp* dsp = dsp_internal::GetWritableDspTable(10);
+  assert(dsp != nullptr);
+  dsp->super_res_coefficients = nullptr;
+#if LIBGAV1_ENABLE_ALL_DSP_FUNCTIONS
+  dsp->super_res = SuperRes_C<10, uint16_t>;
+#else  // !LIBGAV1_ENABLE_ALL_DSP_FUNCTIONS
+  static_cast<void>(dsp);
+#ifndef LIBGAV1_Dsp10bpp_SuperRes
+  dsp->super_res = SuperRes_C<10, uint16_t>;
+#endif
+#endif  // LIBGAV1_ENABLE_ALL_DSP_FUNCTIONS
+}
+#endif
+
+}  // namespace
+
+void SuperResInit_C() {
+  Init8bpp();
+#if LIBGAV1_MAX_BITDEPTH >= 10
+  Init10bpp();
+#endif
+}
+
+}  // namespace dsp
+}  // namespace libgav1