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