1 /******************************************************************************
2  *
3  *  Copyright 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 <base/logging.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   CHECK(size > 0);
38 
39   buffer_t* buffer =
40       static_cast<buffer_t*>(osi_calloc(sizeof(buffer_t) + size));
41 
42   buffer->root = buffer;
43   buffer->refcount = 1;
44   buffer->length = size;
45 
46   return buffer;
47 }
48 
buffer_new_ref(const buffer_t * buf)49 buffer_t* buffer_new_ref(const buffer_t* buf) {
50   CHECK(buf != NULL);
51   return buffer_new_slice(buf, buf->length);
52 }
53 
buffer_new_slice(const buffer_t * buf,size_t slice_size)54 buffer_t* buffer_new_slice(const buffer_t* buf, size_t slice_size) {
55   CHECK(buf != NULL);
56   CHECK(slice_size > 0);
57   CHECK(slice_size <= buf->length);
58 
59   buffer_t* ret = static_cast<buffer_t*>(osi_calloc(sizeof(buffer_t)));
60 
61   ret->root = buf->root;
62   ret->refcount = SIZE_MAX;
63   ret->length = slice_size;
64 
65   ++buf->root->refcount;
66 
67   return ret;
68 }
69 
buffer_free(buffer_t * buffer)70 void buffer_free(buffer_t* buffer) {
71   if (!buffer) 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) osi_free(buffer->root);
76     osi_free(buffer);
77   } else if (--buffer->refcount == 0) {
78     // We're a root node. Roots are only deleted when their refcount goes to 0.
79     osi_free(buffer);
80   }
81 }
82 
buffer_ptr(const buffer_t * buf)83 void* buffer_ptr(const buffer_t* buf) {
84   CHECK(buf != NULL);
85   return buf->root->data + buf->root->length - buf->length;
86 }
87 
buffer_length(const buffer_t * buf)88 size_t buffer_length(const buffer_t* buf) {
89   CHECK(buf != NULL);
90   return buf->length;
91 }
92