pjproject-2.10/third_party/webrtc/src/webrtc/common_audio
ring_buffer.c
/* * 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/common_audio/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 = 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 = 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); }
ring_buffer.h
/* * 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. #ifndef WEBRTC_COMMON_AUDIO_RING_BUFFER_H_ #define WEBRTC_COMMON_AUDIO_RING_BUFFER_H_ #ifdef __cplusplus extern "C" { #endif #include <stddef.h> // size_t typedef struct RingBuffer RingBuffer; // Creates and initializes the buffer. Returns NULL on failure. RingBuffer* WebRtc_CreateBuffer(size_t element_count, size_t element_size); void WebRtc_InitBuffer(RingBuffer* handle); void WebRtc_FreeBuffer(void* handle); // Reads data from the buffer. The |data_ptr| will point to the address where // it is located. If all |element_count| data are feasible to read without // buffer wrap around |data_ptr| will point to the location in the buffer. // Otherwise, the data will be copied to |data| (memory allocation done by the // user) and |data_ptr| points to the address of |data|. |data_ptr| is only // guaranteed to be valid until the next call to WebRtc_WriteBuffer(). // // To force a copying to |data|, pass a NULL |data_ptr|. // // Returns number of elements read. size_t WebRtc_ReadBuffer(RingBuffer* handle, void** data_ptr, void* data, size_t element_count); // Writes |data| to buffer and returns the number of elements written. size_t WebRtc_WriteBuffer(RingBuffer* handle, const void* data, size_t element_count); // Moves the buffer read position and returns the number of elements moved. // Positive |element_count| moves the read position towards the write position, // that is, flushing the buffer. Negative |element_count| moves the read // position away from the the write position, that is, stuffing the buffer. // Returns number of elements moved. int WebRtc_MoveReadPtr(RingBuffer* handle, int element_count); // Returns number of available elements to read. size_t WebRtc_available_read(const RingBuffer* handle); // Returns number of available elements for write. size_t WebRtc_available_write(const RingBuffer* handle); #ifdef __cplusplus } #endif #endif // WEBRTC_COMMON_AUDIO_RING_BUFFER_H_