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 #include <stdint.h>
19 #include "bt_common.h"
20 #include "osi/allocator.h"
21 #include "osi/buffer.h"
22
23 struct buffer_t {
24 buffer_t *root;
25 size_t refcount;
26 size_t length;
27 uint8_t data[];
28 };
29
buffer_new(size_t size)30 buffer_t *buffer_new(size_t size)
31 {
32 assert(size > 0);
33
34 buffer_t *buffer = osi_malloc(sizeof(buffer_t) + size);
35 if (!buffer) {
36 OSI_TRACE_ERROR("%s unable to allocate buffer of %zu bytes.", __func__, size);
37 return NULL;
38 }
39
40 buffer->root = buffer;
41 buffer->refcount = 1;
42 buffer->length = size;
43
44 return buffer;
45 }
46
buffer_new_ref(const buffer_t * buf)47 buffer_t *buffer_new_ref(const buffer_t *buf)
48 {
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 {
55 assert(buf != NULL);
56 assert(slice_size > 0);
57 assert(slice_size <= buf->length);
58
59 buffer_t *ret = osi_calloc(sizeof(buffer_t));
60 if (!ret) {
61 OSI_TRACE_ERROR("%s unable to allocate new buffer for slice of length %zu.", __func__, slice_size);
62 return NULL;
63 }
64
65 ret->root = buf->root;
66 ret->refcount = SIZE_MAX;
67 ret->length = slice_size;
68
69 ++buf->root->refcount;
70
71 return ret;
72 }
73
buffer_free(buffer_t * buffer)74 void buffer_free(buffer_t *buffer)
75 {
76 if (!buffer) {
77 return;
78 }
79
80 if (buffer->root != buffer) {
81 // We're a leaf node. Delete the root node if we're the last referent.
82 if (--buffer->root->refcount == 0) {
83 osi_free(buffer->root);
84 }
85 osi_free(buffer);
86 } else if (--buffer->refcount == 0) {
87 // We're a root node. Roots are only deleted when their refcount goes to 0.
88 osi_free(buffer);
89 }
90 }
91
buffer_ptr(const buffer_t * buf)92 void *buffer_ptr(const buffer_t *buf)
93 {
94 assert(buf != NULL);
95 return buf->root->data + buf->root->length - buf->length;
96 }
97
buffer_length(const buffer_t * buf)98 size_t buffer_length(const buffer_t *buf)
99 {
100 assert(buf != NULL);
101 return buf->length;
102 }
103
