接上文：
【轻量级开源ROS 的机器人设备（5）】--（1）拟议的框架——µROS节点
四、开发工具
为了方便用户应用程序的开发，一个代码生成器，一个 堆栈使用分析器和演示项目包含在框架中包裹。
4.1 代码生成器
手工编写编组过程和主题/服务处理例程可以 需要很多时间，而且这是一个容易出错的任务。编组的产生 过程可以通过处理传递的消息描述符来自动化 与 ROS 包。此外，处理程序例程共享一个通用框架， 可以被利用和重用。既然如此，生成工具，urogen （作为 Python 2.7 脚本 urosgen.py 实现）被开发出来。
4.2 编译流程
图 5.3 中描述的编译流程非常简单。该工具通过一个文件（清单 B.11 中的完整示例）进行配置，其中列出了主题/服务名称和类型，以及一些选项。一旦涉及的消息类型名称已知，该工具就会从已安装 ROS 包的相关 .msg 和 .srv 文件中加载它们的描述。最后，处理消息类型，从而产生编组和解组函数。为配置文件中列出的那些名称生成主题和服务处理程序存根。该工具还为 Doxygen 生成详细的自我文档（未在列表示例和大多数评论中报告）。
4.3 名称修改
所有 ROS 名称都具有类似路径的结构，以 /（斜杠）作为分隔符。 C标识符不能包含它，因此通过将 / 替换为来破坏 ROS 名称__（双下划线）。主题和服务错位名称总是以 __ 开头，因为它们有一个隐含/开头。
4.4 消息
通过调用 rosmsg show 从它的 .msg 文件加载消息类型，它删除注释并具有简洁的语法。其固有结构映射到 C 结构，其中损坏的名称以 msg__ (msg_name) 为前缀。原始类型被直接映射，而嵌套消息类型被声明分别地。为了符合C语言，结构体定义在拓扑顺序；这是可以做到的，因为 ROS 类型不能有循环依赖项。
-
struct
msg__rosgraph_msgs__Log {
-
2
struct
msg__std_msgs__Header header;
-
3
uint8_t level;
-
4 UrosString name;
-
5 UrosString msg;
-
6 UrosString file;
-
7 UrosString function;
-
8
uint32_t line;
-
9
UROS_VARARR(UrosString) topics;
-
10 };
-
11
-
12
#define msg__rosgraph_msgs__Log__DEBUG ((uint8_t)1)
-
13
#define msg__rosgraph_msgs__Log__INFO ((uint8_t)2)
-
14
#define msg__rosgraph_msgs__Log__WARN ((uint8_t)4)
-
15
#define msg__rosgraph_msgs__Log__ERROR ((uint8_t)8)
-
16
#define msg__rosgraph_msgs__Log__FATAL ((uint8_t)16)
Listing 5.1: Definition of the rosgraph_msgs/Log descriptor and its constant values
-
size_t length_msg__rosgraph_msgs__Log(
-
2
struct msg__rosgraph_msgs__Log *objp
-
3 ) {
-
4
size_t length =
0;
-
5
uint32_t i;
-
6
-
7
urosAssert(objp !=
NULL);
-
8
-
9 length +=
length_msg__std_msgs__Header(&objp->header);
-
10 length +=
sizeof(
uint8_t);
-
11 length +=
sizeof(
uint32_t) + objp->name.length;
-
12 length +=
sizeof(
uint32_t) + objp->msg.length;
-
13 length +=
sizeof(
uint32_t) + objp->file.length;
-
14 length +=
sizeof(
uint32_t) + objp->function.length;
-
15 length +=
sizeof(
uint32_t);
-
16 length +=
sizeof(
uint32_t);
-
17 length += (
size_t)objp->topics.length *
sizeof(
uint32_t);
-
18
for (i =
0; i < objp->topics.length; ++i) {
-
19 length += objp->topics.entriesp[i].length;
-
20 }
-
21
-
22
return length;
-
23 }
Listing 5.2: Stream length computation of a rosgraph_msgs/Log message
消息类型示例 rosgraph_msgs/Log 在清单 5.1 中。
代码生成器为以下操作创建函数：初始化，
清理、长度计算、编组和解组。
初始化函数（init_+msg_name，清单 5.3）设置初步的安全值。清理函数（clean_+msg_name，清单 5.4）
释放任何分配的字段，达到安全初始化状态。
长度计算函数（length_+msg_name，清单 5.2）计算
序列化消息的长度。
编组函数（send_+msg_name，清单 5.6）序列化消息内容并通过输出 TCPROS 流发送它们。反而，
解组函数（recv_+msg_name，清单 5.5）反序列化
从传入的 TCPROS 流中接收到消息
-
void
init_msg__rosgraph_msgs__Log(
-
2 struct msg__rosgraph_msgs__Log *objp
-
3 ) {
-
4 uint32_t
i;
-
5
-
6
urosAssert(objp != NULL);
-
7
-
8
init_msg__std_msgs__Header(&objp->header);
-
9
urosStringObjectInit(&objp->name);
-
10
urosStringObjectInit(&objp->msg);
-
11
urosStringObjectInit(&objp->file);
-
12
urosStringObjectInit(&objp->function);
-
13
urosTcpRosArrayObjectInit((UrosTcpRosArray *)&objp->topics);
-
14 for (i =
0; i < objp->topics.length; ++i) {
-
15
urosStringObjectInit(&objp->topics.entriesp[i]);
-
16 }
-
17 }
Listing 5.3: Initialization of a rosgraph_msgs/Log descriptor
-
1 void
clean_msg__rosgraph_msgs__Log(
-
2 struct msg__rosgraph_msgs__Log *objp
-
3 ) {
-
4 uint32_t
i;
-
5
-
6 if (objp == NULL) { return; }
-
7
-
8
clean_msg__std_msgs__Header(&objp->header);
-
9
urosStringClean(&objp->name);
-
10
urosStringClean(&objp->msg);
-
11
urosStringClean(&objp->file);
-
12
urosStringClean(&objp->function);
-
13 for (i =
0; i < objp->topics.length; ++i) {
-
14
urosStringClean(&objp->topics.entriesp[i]);
-
15 }
-
16
urosTcpRosArrayClean((UrosTcpRosArray *)&objp->topics);
-
17 }
-
Listing
5.4: Cleaning function of a rosgraph_msgs/Log descriptor
-
1 uros_err_t
recv_msg__rosgraph_msgs__Log(
-
2 UrosTcpRosStatus *tcpstp,
-
3
struct
msg__rosgraph_msgs__Log *objp
-
4 ) {
-
5 uint32_t i;
-
6
-
7
urosAssert(tcpstp != NULL);
-
8
urosAssert(
urosConnIsValid(tcpstp
->csp));
-
9
urosAssert(objp != NULL);
-
10 #define _CHKOK {
if (tcpstp
->err != UROS_OK) { goto _error; } }
-
11
-
12
recv_msg__std_msgs__Header(tcpstp, &objp
->header); _CHKOK
-
13
urosTcpRosRecvRaw(tcpstp, objp
->level); _CHKOK
-
14
urosTcpRosRecvString(tcpstp, &objp
->name); _CHKOK
-
15
urosTcpRosRecvString(tcpstp, &objp
->msg); _CHKOK
-
16
urosTcpRosRecvString(tcpstp, &objp
->file); _CHKOK
-
17
urosTcpRosRecvString(tcpstp, &objp
->function); _CHKOK
-
18
urosTcpRosRecvRaw(tcpstp, objp
->line); _CHKOK
-
19
urosTcpRosArrayObjectInit((UrosTcpRosArray *)&objp
->topics);
-
20
urosTcpRosRecvRaw(tcpstp, objp
->topics.length); _CHKOK
-
21 objp
->topics.entriesp =
urosArrayNew(objp
->topics.length,
-
22 UrosString);
-
23
if (objp
->topics.entriesp == NULL) { tcpstp
->err = UROS_ERR_NOMEM; goto _error; }
-
24
for (i =
0; i < objp
->topics.length; ++i) {
-
25
urosTcpRosRecvString(tcpstp, &objp
->topics.entriesp[i]); _CHKOK
-
26 }
-
27
-
28
return tcpstp
->err = UROS_OK;
-
29 _error:
-
30
clean_msg__rosgraph_msgs__Log(objp);
-
31
return tcpstp
->err;
-
32 #undef _CHKOK
-
33 }
-
Listing
5.5: Reception and unmarshaling of a rosgraph_msgs/Log message
-
1 uros_err_t
send_msg__rosgraph_msgs__Log(
-
2 UrosTcpRosStatus *tcpstp,
-
3
struct
msg__rosgraph_msgs__Log *objp
-
4 ) {
-
5 uint32_t i;
-
6
-
7
urosAssert(tcpstp != NULL);
-
8
urosAssert(
urosConnIsValid(tcpstp
->csp));
-
9
urosAssert(objp != NULL);
-
10 #define _CHKOK {
if (tcpstp
->err != UROS_OK) {
return tcpstp
->err; } }
-
11
-
12
send_msg__std_msgs__Header(tcpstp, &objp
->header); _CHKOK
-
13
urosTcpRosSendRaw(tcpstp, objp
->level); _CHKOK
-
14
urosTcpRosSendString(tcpstp, &objp
->name); _CHKOK
-
15
urosTcpRosSendString(tcpstp, &objp
->msg); _CHKOK
-
16
urosTcpRosSendString(tcpstp, &objp
->file); _CHKOK
-
17
urosTcpRosSendString(tcpstp, &objp
->function); _CHKOK
-
18
urosTcpRosSendRaw(tcpstp, objp
->line); _CHKOK
-
19
urosTcpRosSendRaw(tcpstp, objp
->topics.length); _CHKOK
-
20
for (i =
0; i < objp
->topics.length; ++i) {
-
21
urosTcpRosSendString(tcpstp, &objp
->topics.entriesp[i]); _CHKOK
-
22 }
-
23
-
24
return tcpstp
->err = UROS_OK;
-
25 #undef _CHKOK
-
26 }
-
Listing
5.6: Marshaling and transmission of a rosgraph_msgs/Log message
4.5 服务讯息
服务消息是一对普通的输入/输出消息，因此被拆分为输入结构（in_srv__ + 损坏的名称，in_name）和输出结构(out_srv__ + mangled name, out_name)，如清单 5.7 所示。他们是
通过调用 rossrv show 从相关的 .srv 文件加载，类似于普通消息。
每个子消息都有专门的初始化（清单 5.9）、清理（清单 5.10）和长度计算（清单 5.8）函数，以及上面看到的赋值和前缀。
只有输入消息有解组函数(recv_+in_name,清单 5.11)，而只有输出消息具有编组功能（send_+out_name，清单 5.12）。
4.6 类型注册
urosMsgTypesRegStaticTypes() 过程将所有消息类型注册到它们各自的静态寄存器（参见第 5.2.1 节），如清单 5.13 所示。
4.7 处理例程
处理例程，除了服务调用的例程，应该在内部工作他们自己的线程。用户可以决定是否放置本地消息变量在堆栈或堆中，优化和协调内存管理；根据经验，小消息描述符放在堆栈上，大消息堆上的描述符。
4.8 主题发布者
主题发布者例程，pub_tpc + mangled name，生成并向订阅者发送纯消息，直到断开连接。生成的模板可以在清单 5.14 中看到，其中消息描述符被分配到堆中。用户只需要移除假人循环语句，并填写 msgp 描述符字段。
4.9 主题订阅者
另一方面，主题订阅者例程 sub_tpc+ 损坏的名称，不断接收和处理消息，直到断开连接。
-
1
struct in_srv__turtlesim__Spawn {
-
2
float x;
-
3
float y;
-
4
float theta;
-
5 UrosString name;
-
6 };
-
7
-
8
struct out_srv__turtlesim__Spawn {
-
9 UrosString name;
-
10 };
Listing 5.7: Definition of the turtlesim/Spawn descriptors
-
1
size_t length_in_srv__turtlesim__Spawn(
-
2
struct in_srv__turtlesim__Spawn *objp
-
3 ) {
-
4
size_t length =
0;
-
5
-
6
urosAssert(objp !=
NULL);
-
7
-
8 length +=
sizeof(
float);
-
9 length +=
sizeof(
float);
-
10 length +=
sizeof(
float);
-
11 length +=
sizeof(
uint32_t) + objp->name.length;
-
12
-
13
return length;
-
14 }
-
15
-
16
size_t length_out_srv__turtlesim__Spawn(
-
17
struct out_srv__turtlesim__Spawn *objp
-
18 ) {
-
19
size_t length =
0;
-
20
-
21
urosAssert(objp !=
NULL);
-
22
-
23 length +=
sizeof(
uint32_t) + objp->name.length;
-
24
-
25
return length;
-
26 }
Listing 5.8: Stream length computation of turtlesim/Spawn messages
如清单 5.15 所示，用户只需要处理收到的消息，msgp。
Service publishers 服务发布者，pub_srv + mangled name，接收请求消息（in_name），处理，然后发送响应如果成功则为消息 (out_name)，如果不成功则为错误字符串。如果尝试仍然存在，则重复这些操作直到断开连接。
清单 5.16 是服务发布者生成的模板。这是一个工会消息接收和传输，因此用户必须为两者提供代码请求处理和响应生成。
4.10 服务调用
服务调用例程 call_srv + 损坏的名称由客户端执行。它向发布者发送请求，然后接收响应或错误字符串。与在其主体内生成或处理消息的其他处理程序例程相反，服务调用例程仅用于通信；消息描述符也在外面分配。清单 5.17 中显示了生成的处理程序的示例。用户不需要做任何事情，但建议在收到响应之前释放请求描述符，以减少内存使用。
-
void
init_in_srv__turtlesim__Spawn(
-
2 struct in_srv__turtlesim__Spawn *objp
-
3 ) {
-
4
urosAssert(objp != NULL);
-
5
-
6
urosStringObjectInit(&objp->name);
-
7 }
-
8
-
9 void
init_out_srv__turtlesim__Spawn(
-
10 struct out_srv__turtlesim__Spawn *objp
-
11 ) {
-
12
urosAssert(objp != NULL);
-
13
-
14
urosStringObjectInit(&objp->name);
-
15 }
-
Listing
5.9: Initialization of turtlesim/Spawn descriptors
-
1 void
clean_in_srv__turtlesim__Spawn(
-
2 struct in_srv__turtlesim__Spawn *objp
-
3 ) {
-
4
urosAssert(objp != NULL);
-
5
-
6
urosStringClean(&objp->name);
-
7 }
-
8
-
9 void
clean_out_srv__turtlesim__Spawn(
-
10 struct out_srv__turtlesim__Spawn *objp
-
11 ) {
-
12
urosAssert(objp != NULL);
-
13
-
14
urosStringClean(&objp->name);
-
15 }
-
Listing
5.10: Cleaning function of turtlesim/Spawn descriptors
-
1 uros_err_t
recv_in_srv__turtlesim__Spawn(
-
2 UrosTcpRosStatus *tcpstp,
-
3
struct
in_srv__turtlesim__Spawn *objp
-
4 ) {
-
5
urosAssert(tcpstp != NULL);
-
6
urosAssert(
urosConnIsValid(tcpstp
->csp));
-
7
urosAssert(objp != NULL);
-
8 #define _CHKOK {
if (tcpstp
->err) { goto _error; } }
-
9
-
10
urosTcpRosRecvRaw(tcpstp, objp
->x); _CHKOK
-
11
urosTcpRosRecvRaw(tcpstp, objp
->y); _CHKOK
-
12
urosTcpRosRecvRaw(tcpstp, objp
->theta); _CHKOK
-
13
urosTcpRosRecvString(tcpstp, &objp
->name); _CHKOK
-
14
-
15
return tcpstp
->err = UROS_OK;
-
16 _error:
-
17
clean_in_srv__turtlesim__Spawn(objp);
-
18
return tcpstp
->err;
-
19 #undef _CHKOK
-
20 }
-
Listing
5.11: Reception and unmarshaling of a turtlesim/Spawn request message
-
1
uros_err_t send_out_srv__turtlesim__Spawn(
-
2 UrosTcpRosStatus *tcpstp,
-
3
struct out_srv__turtlesim__Spawn *objp
-
4 ) {
-
5
urosAssert(tcpstp !=
NULL);
-
6
urosAssert(
urosConnIsValid(tcpstp->csp));
-
7
urosAssert(objp !=
NULL);
-
8
#define _CHKOK { if (tcpstp->err) { return tcpstp->err; } }
-
9
-
10
urosTcpRosSendString(tcpstp, &objp->name); _CHKOK
-
11
-
12
return tcpstp->err = UROS_OK;
-
13
#undef _CHKOK
-
14 }
-
Listing
5.12: Marshaling
and transmission of a turtlesim/Spawn response message
-
1
void urosMsgTypesRegStaticTypes(void) {
-
2
-
3
urosRegisterStaticMsgTypeSZ(
"rosgraph_msgs/Log",
-
4
NULL,
"acffd30cd6b6de30f120938c17c593fb");
-
5
-
6
urosRegisterStaticMsgTypeSZ(
"std_msgs/Header",
-
7
NULL,
"2176decaecbce78abc3b96ef049fabed");
-
8
-
9
urosRegisterStaticSrvTypeSZ(
"turtlesim/Spawn",
-
10
NULL,
"0b2d2e872a8e2887d5ed626f2bf2c561");
-
11 }
-
Listing
5.13: Registration of the
static types used in the examples above
-
1
uros_err_t pub_tpc__rosout(UrosTcpRosStatus *tcpstp) {
-
2
-
3
UROS_TPC_INIT_H(msg__rosgraph_msgs__Log);
-
4
-
5
while (!
urosTcpRosStatusCheckExit(tcpstp)) {
-
6
/* TODO: Generate the contents of the message.*/
-
7
urosThreadSleepSec(
1);
continue;
/* TODO: Remove this dummy line.*/
-
8
-
9
UROS_MSG_SEND_LENGTH(msgp, msg__rosgraph_msgs__Log);
-
10
UROS_MSG_SEND_BODY(msgp, msg__rosgraph_msgs__Log);
-
11
-
12
clean_msg__rosgraph_msgs__Log(msgp);
-
13 }
-
14 tcpstp->err = UROS_OK;
-
15
-
16 _finally:
-
17
UROS_TPC_UNINIT_H(msg__rosgraph_msgs__Log);
-
18
return tcpstp->err;
-
19 }
-
Listing
5.14: Generated handler
template
for a common /rosout publisher
-
1
uros_err_t sub_tpc__rosout(UrosTcpRosStatus *tcpstp) {
-
2
-
3
UROS_TPC_INIT_H(msg__rosgraph_msgs__Log);
-
4
-
5
while (!
urosTcpRosStatusCheckExit(tcpstp)) {
-
6
UROS_MSG_RECV_LENGTH();
-
7
UROS_MSG_RECV_BODY(msgp, msg__rosgraph_msgs__Log);
-
8
-
9
/* TODO: Process the received message.*/
-
10
-
11
clean_msg__rosgraph_msgs__Log(msgp);
-
12 }
-
13 tcpstp->err = UROS_OK;
-
14
-
15 _finally:
-
16
UROS_TPC_UNINIT_H(msg__rosgraph_msgs__Log);
-
17
return tcpstp->err;
-
18 }
-
Listing
5.15: Generated handler
template
for a /rosout subscriber
-
1 uros_err_t
pub_srv__reconfigure(UrosTcpRosStatus *tcpstp) {
-
2
-
3
UROS_SRV_INIT_HISO(in_srv__dynamic_reconfigure__Reconfigure,
-
4 out_srv__dynamic_reconfigure__Reconfigure);
-
5
-
6
do {
-
7
UROS_MSG_RECV_LENGTH();
-
8
UROS_MSG_RECV_BODY(inmsgp, in_srv__dynamic_reconfigure__Reconfigure);
-
9
-
10
/* TODO: Process the request message.*/
-
11 tcpstp
->err = UROS_OK;
-
12
urosStringClean(&tcpstp
->errstr);
-
13 okByte =
1;
-
14
-
15
clean_in_srv__dynamic_reconfigure__Reconfigure(inmsgp);
-
16
-
17
/* TODO: Generate the contents of the response message.*/
-
18
-
19
UROS_SRV_SEND_OKBYTE_ERRSTR();
-
20
UROS_MSG_SEND_LENGTH(&outmsg, out_srv__dynamic_reconfigure__Reconfigure);
-
21
UROS_MSG_SEND_BODY(&outmsg, out_srv__dynamic_reconfigure__Reconfigure);
-
22
-
23
clean_out_srv__dynamic_reconfigure__Reconfigure(&outmsg);
-
24 }
while (tcpstp
->topicp
->flags.persistent &&
-
25 !
urosTcpRosStatusCheckExit(tcpstp));
-
26 tcpstp
->err = UROS_OK;
-
27
-
28 _finally:
-
29
UROS_SRV_UNINIT_HISO(in_srv__dynamic_reconfigure__Reconfigure,
-
30 out_srv__dynamic_reconfigure__Reconfigure);
-
31
return tcpstp
->err;
-
32 }
-
Listing
5.16: Generated handler template
for
a service publisher
-
1 uros_err_t
call_srv__reconfigure(
-
2 UrosTcpRosStatus *tcpstp,
-
3
struct
in_srv__dynamic_reconfigure__Reconfigure *inmsgp,
-
4
struct
out_srv__dynamic_reconfigure__Reconfigure *outmsgp
-
5 ) {
-
6
-
7
UROS_SRVCALL_INIT(in_srv__dynamic_reconfigure__Reconfigure,
-
8 out_srv__dynamic_reconfigure__Reconfigure);
-
9
-
10
UROS_MSG_SEND_LENGTH(inmsgp, in_srv__dynamic_reconfigure__Reconfigure);
-
11
UROS_MSG_SEND_BODY(inmsgp, in_srv__dynamic_reconfigure__Reconfigure);
-
12
-
13
/* TODO: Dispose the contents of the request message.*/
-
14
-
15
UROS_SRV_RECV_OKBYTE();
-
16
UROS_MSG_RECV_LENGTH();
-
17
UROS_MSG_RECV_BODY(outmsgp, out_srv__dynamic_reconfigure__Reconfigure);
-
18
-
19 tcpstp
->err = UROS_OK;
-
20 _finally:
-
21
return tcpstp
->err;
-
22 }
-
Listing
5.17: Generated handler template
for
a client service call
转载：https://blog.csdn.net/gongdiwudu/article/details/128341030
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