1 /******************************************************************************
2  *
3  *  Copyright (C) 2017 Google Inc.
4  *
5  *  Licensed under the Apache License, Version 2.0 (the "License");
6  *  you may not use this file except in compliance with the License.
7  *  You may obtain a copy of the License at:
8  *
9  *  http://www.apache.org/licenses/LICENSE-2.0
10  *
11  *  Unless required by applicable law or agreed to in writing, software
12  *  distributed under the License is distributed on an "AS IS" BASIS,
13  *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14  *  See the License for the specific language governing permissions and
15  *  limitations under the License.
16  *
17  ******************************************************************************/
18 
19 #pragma once
20 
21 #include <stdint.h>
22 
23 typedef struct ringbuffer_t ringbuffer_t;
24 
25 // NOTE:
26 // None of the functions below are thread safe when it comes to accessing the
27 // *rb pointer. It is *NOT* possible to insert and pop/delete at the same time.
28 // Callers must protect the *rb pointer separately.
29 
30 // Create a ringbuffer with the specified size
31 // Returns NULL if memory allocation failed. Resulting pointer must be freed
32 // using |ringbuffer_free|.
33 ringbuffer_t* ringbuffer_init(const size_t size);
34 
35 // Frees the ringbuffer structure and buffer
36 // Save to call with NULL.
37 void ringbuffer_free(ringbuffer_t* rb);
38 
39 // Returns remaining buffer size
40 size_t ringbuffer_available(const ringbuffer_t* rb);
41 
42 // Returns size of data in buffer
43 size_t ringbuffer_size(const ringbuffer_t* rb);
44 
45 // Attempts to insert up to |length| bytes of data at |p| into the buffer
46 // Return actual number of bytes added. Can be less than |length| if buffer
47 // is full.
48 size_t ringbuffer_insert(ringbuffer_t* rb, const uint8_t* p, size_t length);
49 
50 // Peek |length| number of bytes from the ringbuffer, starting at |offset|,
51 // into the buffer |p|. Return the actual number of bytes peeked. Can be less
52 // than |length| if there is less than |length| data available. |offset| must
53 // be non-negative.
54 size_t ringbuffer_peek(const ringbuffer_t* rb, off_t offset, uint8_t* p,
55                        size_t length);
56 
57 // Does the same as |ringbuffer_peek|, but also advances the ring buffer head
58 size_t ringbuffer_pop(ringbuffer_t* rb, uint8_t* p, size_t length);
59 
60 // Deletes |length| bytes from the ringbuffer starting from the head
61 // Return actual number of bytes deleted.
62 size_t ringbuffer_delete(ringbuffer_t* rb, size_t length);
63