1 files changed, 232 insertions, 0 deletions
diff --git a/third_party/libwebrtc/common_audio/ring_buffer.c b/third_party/libwebrtc/common_audio/ring_buffer.c
new file mode 100644
index 0000000000..590f5f9bf1
--- /dev/null
+++ b/third_party/libwebrtc/common_audio/ring_buffer.c
@@ -0,0 +1,232 @@
+/*
+ *  Copyright (c) 2011 The WebRTC project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+// A ring buffer to hold arbitrary data. Provides no thread safety. Unless
+// otherwise specified, functions return 0 on success and -1 on error.
+
+#include "common_audio/ring_buffer.h"
+
+#include <stddef.h>  // size_t
+#include <stdlib.h>
+#include <string.h>
+
+// Get address of region(s) from which we can read data.
+// If the region is contiguous, `data_ptr_bytes_2` will be zero.
+// If non-contiguous, `data_ptr_bytes_2` will be the size in bytes of the second
+// region. Returns room available to be read or `element_count`, whichever is
+// smaller.
+static size_t GetBufferReadRegions(RingBuffer* buf,
+                                   size_t element_count,
+                                   void** data_ptr_1,
+                                   size_t* data_ptr_bytes_1,
+                                   void** data_ptr_2,
+                                   size_t* data_ptr_bytes_2) {
+
+  const size_t readable_elements = WebRtc_available_read(buf);
+  const size_t read_elements = (readable_elements < element_count ?
+      readable_elements : element_count);
+  const size_t margin = buf->element_count - buf->read_pos;
+
+  // Check to see if read is not contiguous.
+  if (read_elements > margin) {
+    // Write data in two blocks that wrap the buffer.
+    *data_ptr_1 = buf->data + buf->read_pos * buf->element_size;
+    *data_ptr_bytes_1 = margin * buf->element_size;
+    *data_ptr_2 = buf->data;
+    *data_ptr_bytes_2 = (read_elements - margin) * buf->element_size;
+  } else {
+    *data_ptr_1 = buf->data + buf->read_pos * buf->element_size;
+    *data_ptr_bytes_1 = read_elements * buf->element_size;
+    *data_ptr_2 = NULL;
+    *data_ptr_bytes_2 = 0;
+  }
+
+  return read_elements;
+}
+
+RingBuffer* WebRtc_CreateBuffer(size_t element_count, size_t element_size) {
+  RingBuffer* self = NULL;
+  if (element_count == 0 || element_size == 0) {
+    return NULL;
+  }
+
+  self = malloc(sizeof(RingBuffer));
+  if (!self) {
+    return NULL;
+  }
+
+  self->data = malloc(element_count * element_size);
+  if (!self->data) {
+    free(self);
+    self = NULL;
+    return NULL;
+  }
+
+  self->element_count = element_count;
+  self->element_size = element_size;
+  WebRtc_InitBuffer(self);
+
+  return self;
+}
+
+void WebRtc_InitBuffer(RingBuffer* self) {
+  self->read_pos = 0;
+  self->write_pos = 0;
+  self->rw_wrap = SAME_WRAP;
+
+  // Initialize buffer to zeros
+  memset(self->data, 0, self->element_count * self->element_size);
+}
+
+void WebRtc_FreeBuffer(void* handle) {
+  RingBuffer* self = (RingBuffer*)handle;
+  if (!self) {
+    return;
+  }
+
+  free(self->data);
+  free(self);
+}
+
+size_t WebRtc_ReadBuffer(RingBuffer* self,
+                         void** data_ptr,
+                         void* data,
+                         size_t element_count) {
+
+  if (self == NULL) {
+    return 0;
+  }
+  if (data == NULL) {
+    return 0;
+  }
+
+  {
+    void* buf_ptr_1 = NULL;
+    void* buf_ptr_2 = NULL;
+    size_t buf_ptr_bytes_1 = 0;
+    size_t buf_ptr_bytes_2 = 0;
+    const size_t read_count = GetBufferReadRegions(self,
+                                                   element_count,
+                                                   &buf_ptr_1,
+                                                   &buf_ptr_bytes_1,
+                                                   &buf_ptr_2,
+                                                   &buf_ptr_bytes_2);
+    if (buf_ptr_bytes_2 > 0) {
+      // We have a wrap around when reading the buffer. Copy the buffer data to
+      // `data` and point to it.
+      memcpy(data, buf_ptr_1, buf_ptr_bytes_1);
+      memcpy(((char*) data) + buf_ptr_bytes_1, buf_ptr_2, buf_ptr_bytes_2);
+      buf_ptr_1 = data;
+    } else if (!data_ptr) {
+      // No wrap, but a memcpy was requested.
+      memcpy(data, buf_ptr_1, buf_ptr_bytes_1);
+    }
+    if (data_ptr) {
+      // `buf_ptr_1` == `data` in the case of a wrap.
+      *data_ptr = read_count == 0 ? NULL : buf_ptr_1;
+    }
+
+    // Update read position
+    WebRtc_MoveReadPtr(self, (int) read_count);
+
+    return read_count;
+  }
+}
+
+size_t WebRtc_WriteBuffer(RingBuffer* self,
+                          const void* data,
+                          size_t element_count) {
+  if (!self) {
+    return 0;
+  }
+  if (!data) {
+    return 0;
+  }
+
+  {
+    const size_t free_elements = WebRtc_available_write(self);
+    const size_t write_elements = (free_elements < element_count ? free_elements
+        : element_count);
+    size_t n = write_elements;
+    const size_t margin = self->element_count - self->write_pos;
+
+    if (write_elements > margin) {
+      // Buffer wrap around when writing.
+      memcpy(self->data + self->write_pos * self->element_size,
+             data, margin * self->element_size);
+      self->write_pos = 0;
+      n -= margin;
+      self->rw_wrap = DIFF_WRAP;
+    }
+    memcpy(self->data + self->write_pos * self->element_size,
+           ((const char*) data) + ((write_elements - n) * self->element_size),
+           n * self->element_size);
+    self->write_pos += n;
+
+    return write_elements;
+  }
+}
+
+int WebRtc_MoveReadPtr(RingBuffer* self, int element_count) {
+  if (!self) {
+    return 0;
+  }
+
+  {
+    // We need to be able to take care of negative changes, hence use "int"
+    // instead of "size_t".
+    const int free_elements = (int) WebRtc_available_write(self);
+    const int readable_elements = (int) WebRtc_available_read(self);
+    int read_pos = (int) self->read_pos;
+
+    if (element_count > readable_elements) {
+      element_count = readable_elements;
+    }
+    if (element_count < -free_elements) {
+      element_count = -free_elements;
+    }
+
+    read_pos += element_count;
+    if (read_pos > (int) self->element_count) {
+      // Buffer wrap around. Restart read position and wrap indicator.
+      read_pos -= (int) self->element_count;
+      self->rw_wrap = SAME_WRAP;
+    }
+    if (read_pos < 0) {
+      // Buffer wrap around. Restart read position and wrap indicator.
+      read_pos += (int) self->element_count;
+      self->rw_wrap = DIFF_WRAP;
+    }
+
+    self->read_pos = (size_t) read_pos;
+
+    return element_count;
+  }
+}
+
+size_t WebRtc_available_read(const RingBuffer* self) {
+  if (!self) {
+    return 0;
+  }
+
+  if (self->rw_wrap == SAME_WRAP) {
+    return self->write_pos - self->read_pos;
+  } else {
+    return self->element_count - self->read_pos + self->write_pos;
+  }
+}
+
+size_t WebRtc_available_write(const RingBuffer* self) {
+  if (!self) {
+    return 0;
+  }
+
+  return self->element_count - WebRtc_available_read(self);
+}