1 files changed, 80 insertions, 0 deletions
diff --git a/third_party/aom/aom_dsp/flow_estimation/corner_detect.h b/third_party/aom/aom_dsp/flow_estimation/corner_detect.h
new file mode 100644
index 0000000000..d05846ce5d
--- /dev/null
+++ b/third_party/aom/aom_dsp/flow_estimation/corner_detect.h
@@ -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.
+ */
+
+#ifndef AOM_AOM_DSP_FLOW_ESTIMATION_CORNER_DETECT_H_
+#define AOM_AOM_DSP_FLOW_ESTIMATION_CORNER_DETECT_H_
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdbool.h>
+#include <memory.h>
+
+#include "aom_dsp/pyramid.h"
+#include "aom_util/aom_thread.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#define MAX_CORNERS 4096
+
+typedef struct corner_list {
+#if CONFIG_MULTITHREAD
+  // Mutex which is used to prevent the corner list from being computed twice
+  // at the same time
+  //
+  // Semantics:
+  // * This mutex must be held whenever reading or writing the `valid` flag
+  //
+  // * This mutex must also be held while computing the image pyramid,
+  //   to ensure that only one thread may do so at a time.
+  //
+  // * However, once you have read the valid flag and seen a true value,
+  //   it is safe to drop the mutex and read from the remaining fields.
+  //   This is because, once the image pyramid is computed, its contents
+  //   will not be changed until the parent frame buffer is recycled,
+  //   which will not happen until there are no more outstanding references
+  //   to the frame buffer.
+  pthread_mutex_t mutex;
+#endif  // CONFIG_MULTITHREAD
+  // Flag indicating whether the corner list contains valid data
+  bool valid;
+  // Number of corners found
+  int num_corners;
+  // (x, y) coordinates of each corner
+  int corners[2 * MAX_CORNERS];
+} CornerList;
+
+size_t av1_get_corner_list_size(void);
+
+CornerList *av1_alloc_corner_list(void);
+
+bool av1_compute_corner_list(const ImagePyramid *pyr, CornerList *corners);
+
+#ifndef NDEBUG
+// Check if a corner list has already been computed.
+// This is mostly a debug helper - as it is necessary to hold corners->mutex
+// while reading the valid flag, we cannot just write:
+//   assert(corners->valid);
+// This function allows the check to be correctly written as:
+//   assert(aom_is_corner_list_valid(corners));
+bool aom_is_corner_list_valid(CornerList *corners);
+#endif
+
+void av1_invalidate_corner_list(CornerList *corners);
+
+void av1_free_corner_list(CornerList *corners);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif  // AOM_AOM_DSP_FLOW_ESTIMATION_CORNER_DETECT_H_