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1  /******************************************************************************
2   *
3   *  Copyright (C) 2014 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  #define LOG_TAG "bt_osi_buffer"
20  
21  #include "osi/include/buffer.h"
22  
23  #include <assert.h>
24  #include <stdint.h>
25  
26  #include "osi/include/allocator.h"
27  #include "osi/include/log.h"
28  
29  struct buffer_t {
30    buffer_t *root;
31    size_t refcount;
32    size_t length;
33    uint8_t data[];
34  };
35  
buffer_new(size_t size)36  buffer_t *buffer_new(size_t size) {
37    assert(size > 0);
38  
39    buffer_t *buffer = osi_calloc(sizeof(buffer_t) + size);
40  
41    buffer->root = buffer;
42    buffer->refcount = 1;
43    buffer->length = size;
44  
45    return buffer;
46  }
47  
buffer_new_ref(const buffer_t * buf)48  buffer_t *buffer_new_ref(const buffer_t *buf) {
49    assert(buf != NULL);
50    return buffer_new_slice(buf, buf->length);
51  }
52  
buffer_new_slice(const buffer_t * buf,size_t slice_size)53  buffer_t *buffer_new_slice(const buffer_t *buf, size_t slice_size) {
54    assert(buf != NULL);
55    assert(slice_size > 0);
56    assert(slice_size <= buf->length);
57  
58    buffer_t *ret = osi_calloc(sizeof(buffer_t));
59  
60    ret->root = buf->root;
61    ret->refcount = SIZE_MAX;
62    ret->length = slice_size;
63  
64    ++buf->root->refcount;
65  
66    return ret;
67  }
68  
buffer_free(buffer_t * buffer)69  void buffer_free(buffer_t *buffer) {
70    if (!buffer)
71      return;
72  
73    if (buffer->root != buffer) {
74      // We're a leaf node. Delete the root node if we're the last referent.
75      if (--buffer->root->refcount == 0)
76        osi_free(buffer->root);
77      osi_free(buffer);
78    } else if (--buffer->refcount == 0) {
79      // We're a root node. Roots are only deleted when their refcount goes to 0.
80      osi_free(buffer);
81    }
82  }
83  
buffer_ptr(const buffer_t * buf)84  void *buffer_ptr(const buffer_t *buf) {
85    assert(buf != NULL);
86    return buf->root->data + buf->root->length - buf->length;
87  }
88  
buffer_length(const buffer_t * buf)89  size_t buffer_length(const buffer_t *buf) {
90    assert(buf != NULL);
91    return buf->length;
92  }
93