Revert of Moved the ringbuffer to be built using C++

webrtc/modules/audio_processing/utility/ring_buffer.cc

-/*
- *  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 "webrtc/modules/audio_processing/utility/ring_buffer.h"
-
-#include <stddef.h>  // size_t
-#include <stdlib.h>
-#include <string.h>
-
-enum Wrap {
-  SAME_WRAP,
-  DIFF_WRAP
-};
-
-struct RingBuffer {
-  size_t read_pos;
-  size_t write_pos;
-  size_t element_count;
-  size_t element_size;
-  enum Wrap rw_wrap;
-  char* data;
-};
-
-// 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 = static_cast<RingBuffer*>(malloc(sizeof(RingBuffer)));
-  if (!self) {
-    return NULL;
-  }
-
-  self->data = static_cast<char*>(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 = static_cast<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(static_cast<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 = buf_ptr_1;
-    }
-
-    // Update read position
-    WebRtc_MoveReadPtr(self, static_cast<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 = static_cast<int>(WebRtc_available_write(self));
-    const int readable_elements = static_cast<int>(WebRtc_available_read(self));
-    int read_pos = static_cast<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 > static_cast<int>(self->element_count)) {
-      // Buffer wrap around. Restart read position and wrap indicator.
-      read_pos -= static_cast<int>(self->element_count);
-      self->rw_wrap = SAME_WRAP;
-    }
-    if (read_pos < 0) {
-      // Buffer wrap around. Restart read position and wrap indicator.
-      read_pos += static_cast<int>(self->element_count);
-      self->rw_wrap = DIFF_WRAP;
-    }
-
-    self->read_pos = static_cast<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);
-}