Import aom library

This is the reference implementation for the Alliance for Open Media's av1 video code.

The commit used was 4d668d7feb1f8abd809d1bca0418570a7f142a36.

third_party/aom/aom_dsp/arm/subtract_neon.c

@@ -0,0 +1,80 @@
+/*
+ * Copyright (c) 2016, 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.
+ */
+
+#include <arm_neon.h>
+
+#include "./aom_config.h"
+#include "aom/aom_integer.h"
+
+void aom_subtract_block_neon(int rows, int cols, int16_t *diff,
+                             ptrdiff_t diff_stride, const uint8_t *src,
+                             ptrdiff_t src_stride, const uint8_t *pred,
+                             ptrdiff_t pred_stride) {
+  int r, c;
+
+  if (cols > 16) {
+    for (r = 0; r < rows; ++r) {
+      for (c = 0; c < cols; c += 32) {
+        const uint8x16_t v_src_00 = vld1q_u8(&src[c + 0]);
+        const uint8x16_t v_src_16 = vld1q_u8(&src[c + 16]);
+        const uint8x16_t v_pred_00 = vld1q_u8(&pred[c + 0]);
+        const uint8x16_t v_pred_16 = vld1q_u8(&pred[c + 16]);
+        const uint16x8_t v_diff_lo_00 =
+            vsubl_u8(vget_low_u8(v_src_00), vget_low_u8(v_pred_00));
+        const uint16x8_t v_diff_hi_00 =
+            vsubl_u8(vget_high_u8(v_src_00), vget_high_u8(v_pred_00));
+        const uint16x8_t v_diff_lo_16 =
+            vsubl_u8(vget_low_u8(v_src_16), vget_low_u8(v_pred_16));
+        const uint16x8_t v_diff_hi_16 =
+            vsubl_u8(vget_high_u8(v_src_16), vget_high_u8(v_pred_16));
+        vst1q_s16(&diff[c + 0], vreinterpretq_s16_u16(v_diff_lo_00));
+        vst1q_s16(&diff[c + 8], vreinterpretq_s16_u16(v_diff_hi_00));
+        vst1q_s16(&diff[c + 16], vreinterpretq_s16_u16(v_diff_lo_16));
+        vst1q_s16(&diff[c + 24], vreinterpretq_s16_u16(v_diff_hi_16));
+      }
+      diff += diff_stride;
+      pred += pred_stride;
+      src += src_stride;
+    }
+  } else if (cols > 8) {
+    for (r = 0; r < rows; ++r) {
+      const uint8x16_t v_src = vld1q_u8(&src[0]);
+      const uint8x16_t v_pred = vld1q_u8(&pred[0]);
+      const uint16x8_t v_diff_lo =
+          vsubl_u8(vget_low_u8(v_src), vget_low_u8(v_pred));
+      const uint16x8_t v_diff_hi =
+          vsubl_u8(vget_high_u8(v_src), vget_high_u8(v_pred));
+      vst1q_s16(&diff[0], vreinterpretq_s16_u16(v_diff_lo));
+      vst1q_s16(&diff[8], vreinterpretq_s16_u16(v_diff_hi));
+      diff += diff_stride;
+      pred += pred_stride;
+      src += src_stride;
+    }
+  } else if (cols > 4) {
+    for (r = 0; r < rows; ++r) {
+      const uint8x8_t v_src = vld1_u8(&src[0]);
+      const uint8x8_t v_pred = vld1_u8(&pred[0]);
+      const uint16x8_t v_diff = vsubl_u8(v_src, v_pred);
+      vst1q_s16(&diff[0], vreinterpretq_s16_u16(v_diff));
+      diff += diff_stride;
+      pred += pred_stride;
+      src += src_stride;
+    }
+  } else {
+    for (r = 0; r < rows; ++r) {
+      for (c = 0; c < cols; ++c) diff[c] = src[c] - pred[c];
+
+      diff += diff_stride;
+      pred += pred_stride;
+      src += src_stride;
+    }
+  }
+}