1 /*
2  * Copyright (C) 2010 The Android Open Source Project
3  *
4  * Licensed under the Apache License, Version 2.0 (the "License");
5  * you may not use this file except in compliance with the License.
6  * You may obtain a copy of the License at
7  *
8  *      http://www.apache.org/licenses/LICENSE-2.0
9  *
10  * Unless required by applicable law or agreed to in writing, software
11  * distributed under the License is distributed on an "AS IS" BASIS,
12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13  * See the License for the specific language governing permissions and
14  * limitations under the License.
15  */
16 
17 #ifndef ANDROID_GUI_SENSOR_CHANNEL_H
18 #define ANDROID_GUI_SENSOR_CHANNEL_H
19 
20 #include <stdint.h>
21 #include <sys/types.h>
22 
23 #include <utils/Errors.h>
24 #include <utils/RefBase.h>
25 #include <cutils/log.h>
26 
27 
28 namespace android {
29 // ----------------------------------------------------------------------------
30 class Parcel;
31 
32 class BitTube : public RefBase
33 {
34 public:
35 
36     // creates a BitTube with a default (4KB) send buffer
37     BitTube();
38 
39     // creates a BitTube with a a specified send and receive buffer size
40     explicit BitTube(size_t bufsize);
41 
42     explicit BitTube(const Parcel& data);
43     virtual ~BitTube();
44 
45     // check state after construction
46     status_t initCheck() const;
47 
48     // get receive file-descriptor
49     int getFd() const;
50 
51     // get the send file-descriptor.
52     int getSendFd() const;
53 
54     // send objects (sized blobs). All objects are guaranteed to be written or the call fails.
55     template <typename T>
sendObjects(const sp<BitTube> & tube,T const * events,size_t count)56     static ssize_t sendObjects(const sp<BitTube>& tube,
57             T const* events, size_t count) {
58         return sendObjects(tube, events, count, sizeof(T));
59     }
60 
61     // receive objects (sized blobs). If the receiving buffer isn't large enough,
62     // excess messages are silently discarded.
63     template <typename T>
recvObjects(const sp<BitTube> & tube,T * events,size_t count)64     static ssize_t recvObjects(const sp<BitTube>& tube,
65             T* events, size_t count) {
66         return recvObjects(tube, events, count, sizeof(T));
67     }
68 
69     // parcels this BitTube
70     status_t writeToParcel(Parcel* reply) const;
71 
72 private:
73     void init(size_t rcvbuf, size_t sndbuf);
74 
75     // send a message. The write is guaranteed to send the whole message or fail.
76     ssize_t write(void const* vaddr, size_t size);
77 
78     // receive a message. the passed buffer must be at least as large as the
79     // write call used to send the message, excess data is silently discarded.
80     ssize_t read(void* vaddr, size_t size);
81 
82     int mSendFd;
83     mutable int mReceiveFd;
84 
85     static ssize_t sendObjects(const sp<BitTube>& tube,
86             void const* events, size_t count, size_t objSize);
87 
88     static ssize_t recvObjects(const sp<BitTube>& tube,
89             void* events, size_t count, size_t objSize);
90 };
91 
92 // ----------------------------------------------------------------------------
93 }; // namespace android
94 
95 #endif // ANDROID_GUI_SENSOR_CHANNEL_H
96