RPlidar学习（三）——RPlidar源代码库

1.头文件简介

rplidar.h//一般情况下开发的项目中仅需要引入该头文件即可使用 RPLIDAR SDK 的所有功能。

rptypes.h//平台无关的结构和常量定义

rplidar_protocol.h//定义了 RPLIDAR 通讯协议文档中描述的底层相关数据结构和常量定义。

rplidar_cmd.h//定义了 RPLIDAR 通讯协议文档中描述的各类请求/应答相关的数据结构和常量定义。

rplidar_driver.h//定义了 SDK 核心驱动接口: RPlidarDriver 的类声明。

2.头文件解析（代码理解加部分英文单词翻译）

（1）rplidar_protocol.h

#pragma once（避免同一个文件被include多次）

// RP-Lidar Input Packets（输入数据包）

#define RPLIDAR_CMD_SYNC_BYTE        0xA5(十六进制0x开头）//请求报文开始字节

#define RPLIDAR_CMDFLAG_HAS_PAYLOAD  0x80  //请求报文负载

#define RPLIDAR_ANS_SYNC_BYTE1       0xA5 //应答报文起始标志1

#define RPLIDAR_ANS_SYNC_BYTE2       0x5A //应答报文起始标志2

#define RPLIDAR_ANS_PKTFLAG_LOOP     0x1 //多次应答模式

#define RPLIDAR_ANS_HEADER_SIZE_MASK        0x3FFFFFFF
#define RPLIDAR_ANS_HEADER_SUBTYPE_SHIFT    (30)

#if defined(_WIN32)
#pragma pack(1)//每个结构成员都必须限制在1个字节之内 ，也就是说储存在内存中是连续的
#endif
//请求报文格式
typedef struct _rplidar_cmd_packet_t {
    _u8 syncByte; //must be RPLIDAR_CMD_SYNC_BYTE //起始标志
    _u8 cmd_flag;  //请求命令
    _u8 size; //负载长度
    _u8 data[0]; //请求负载数据

} __attribute__((packed)) rplidar_cmd_packet_t;//__attribute__ ((packed)) 的作用就是告诉编译器取消结构在编译过程中的优化对齐,按照实际占用字节数进行对齐

//使用之后才会是几字节就是几字节，否则就每个变量的字节长度都跟结构体中变量字节长度最长相同

//应答报文格式

typedef struct _rplidar_ans_header_t {

    _u8  syncByte1; // must be RPLIDAR_ANS_SYNC_BYTE1（起始标志1）
    _u8  syncByte2; // must be RPLIDAR_ANS_SYNC_BYTE2（起始标志2）
    _u32 size_q30_subtype; // see _u32 size:30; _u32 subType:2;（应答报文长度）
    _u8  type; //应答模式
} __attribute__((packed)) rplidar_ans_header_t;

#if defined(_WIN32)
#pragma pack()
#endif

//按照实际占用字节数进行对齐

（2）rplidar_cmd.h 

#pragma once

#include "rplidar_protocol.h"

// Commands
//-----------------------------------------

// Commands without payload(负载） and response（响应）
#define RPLIDAR_CMD_STOP               0x25 //离开扫描模式，进入空闲状态
#define RPLIDAR_CMD_SCAN               0x20 //请求进入扫描采样状态
#define RPLIDAR_CMD_FORCE_SCAN         0x21 //请求进入扫描采样状态，强制数据输出
#define RPLIDAR_CMD_RESET              0x40 //测距核心软重启

// Commands without payload but have response
#define RPLIDAR_CMD_GET_DEVICE_INFO    0x50 //获取设备序列号等信息
#define RPLIDAR_CMD_GET_DEVICE_HEALTH  0x52 //获取设备健康状态

#define RPLIDAR_CMD_GET_SAMPLERATE     0x59 //added in fw 1.17获取单次激光测距的用时

// Commands with payload and have response
#define RPLIDAR_CMD_EXPRESS_SCAN       0x82 //added in fw 1.17请求进入扫描状态，幷工作在最高采样频率下

//add for A2 to set RPLIDAR motor pwm（脉宽调变） when using accessory board（开发系统)
#define RPLIDAR_CMD_SET_MOTOR_PWM      0xF0// 设置PWM
#define RPLIDAR_CMD_GET_ACC_BOARD_FLAG 0xFF//系统标志

#if defined(_WIN32)
#pragma pack(1)
#endif


// Payloads
// ------------------------------------------
#define RPLIDAR_EXPRESS_SCAN_MODE_NORMAL  (正常模式）    0
#define RPLIDAR_EXPRESS_SCAN_MODE_FIXANGLE（固定角度）    1
typedef struct _rplidar_payload_express_scan_t { //带有负载的数据包
    _u8   working_mode;
    _u32  reserved;
} __attribute__((packed)) rplidar_payload_express_scan_t;

#define MAX_MOTOR_PWM               1023//电机脉宽最大值

#define DEFAULT_MOTOR_PWM           660//电机脉宽默认值

//电机PWM结构

typedef struct _rplidar_payload_motor_pwm_t {
    _u16 pwm_value;

} __attribute__((packed)) rplidar_payload_motor_pwm_t;

//开发系统标志
typedef struct _rplidar_payload_acc_board_flag_t {
    _u32 reserved;
} __attribute__((packed)) rplidar_payload_acc_board_flag_t;

// Response
// ------------------------------------------
#define RPLIDAR_ANS_TYPE_DEVINFO          0x4//设备信心获取 起始应答结尾
#define RPLIDAR_ANS_TYPE_DEVHEALTH        0x6//设备健康状态获取 起始应答结尾

#define RPLIDAR_ANS_TYPE_MEASUREMENT                0x81//普通采集
// Added in FW ver 1.17
#define RPLIDAR_ANS_TYPE_MEASUREMENT_CAPSULED       0x82//高速采集

// Added in FW ver 1.17
#define RPLIDAR_ANS_TYPE_SAMPLE_RATE      0x15

#define RPLIDAR_ANS_TYPE_ACC_BOARD_FLAG   0xFF

#define RPLIDAR_RESP_ACC_BOARD_FLAG_MOTOR_CTRL_SUPPORT_MASK      (0x1)
typedef struct _rplidar_response_acc_board_flag_t {
    _u32 support_flag;

} __attribute__((packed)) rplidar_response_acc_board_flag_t;

//设备状态
#define RPLIDAR_STATUS_OK                 0x0
#define RPLIDAR_STATUS_WARNING            0x1
#define RPLIDAR_STATUS_ERROR              0x2

#define RPLIDAR_RESP_MEASUREMENT_SYNCBIT        (0x1<<0)
#define RPLIDAR_RESP_MEASUREMENT_QUALITY_SHIFT  2
#define RPLIDAR_RESP_MEASUREMENT_CHECKBIT       (0x1<<0)

#define RPLIDAR_RESP_MEASUREMENT_ANGLE_SHIFT    1

//激光测距用时获取数据包

typedef struct _rplidar_response_sample_rate_t {
    _u16  std_sample_duration_us; //在标准扫描模式下，设备测距核心进行单次激光测距的耗时 单位：微秒
    _u16  express_sample_duration_us;//在高速采样模式下，设备测距核心进行单次激光测距的耗时 单位：微妙

} __attribute__((packed)) rplidar_response_sample_rate_t;

//激光测距测量节点数据包

typedef struct _rplidar_response_measurement_node_t {
    _u8    sync_quality;      // syncbit:1;syncbit_inverse:1;quality:6;//信号质量
    _u16   angle_q6_checkbit; // check_bit:1;angle_q6:15;//测距点相对于RPLIDAR朝向夹角 实际角度 = angle_q6 / 64.0 Deg
    _u16   distance_q2;//测距点相对于RPLIDAR的距离 实际距离 = distance_q2 / 4.0 mm
} __attribute__((packed)) rplidar_response_measurement_node_t;

//[distance_sync flags]
#define RPLIDAR_RESP_MEASUREMENT_EXP_ANGLE_MASK           (0x3)

#define RPLIDAR_RESP_MEASUREMENT_EXP_DISTANCE_MASK        (0xFC)

// 激光测距小屋测量节点数据包

typedef struct _rplidar_response_cabin_nodes_t {
    _u16   distance_angle_1; // see [distance_sync flags]
    _u16   distance_angle_2; // see [distance_sync flags]
    _u8    offset_angles_q3;  
} __attribute__((packed)) rplidar_response_cabin_nodes_t;   


#define RPLIDAR_RESP_MEASUREMENT_EXP_SYNC_1               0xA
#define RPLIDAR_RESP_MEASUREMENT_EXP_SYNC_2               0x5

#define RPLIDAR_RESP_MEASUREMENT_EXP_SYNCBIT              (0x1<<15)
// 激光测距容器测量节点数据包
typedef struct _rplidar_response_capsule_measurement_nodes_t {
    _u8                             s_checksum_1; // see [s_checksum_1]
    _u8                             s_checksum_2; // see [s_checksum_1]
    _u16                            start_angle_sync_q6;
    rplidar_response_cabin_nodes_t  cabins[16];

} __attribute__((packed)) rplidar_response_capsule_measurement_nodes_t;

//设备信息数据报文

typedef struct _rplidar_response_device_info_t {
    _u8   model;
    _u16  firmware_version;
    _u8   hardware_version;
    _u8   serialnum[16];

} __attribute__((packed)) rplidar_response_device_info_t;

//设备健康信息数据报文

typedef struct _rplidar_response_device_health_t {
    _u8   status;
    _u16  error_code;
} __attribute__((packed)) rplidar_response_device_health_t;

#if defined(_WIN32)
#pragma pack()

#endif

（3）rplidar_driver.h

#pragma once


#ifndef __cplusplus
#error "The RPlidar SDK requires a C++ compiler to be built"
#endif

namespace rp { namespace standalone{ namespace rplidar {

class RPlidarDriver {
public:
    enum {
        DEFAULT_TIMEOUT = 2000, //枚举量默认超时时间2000 ms
    };

    enum {
        DRIVER_TYPE_SERIALPORT = 0x0,//枚举量驱动程序类型串口为0x0（linux被驱动使用的连接类型）
    };
public:
    /// Create an RPLIDAR Driver Instance（实例）
    /// This interface（接口） should be invoked（调用） first before any other operations（操作）
    ///
    /// \param（参数） drivertype（驱动类型）（ the connection type used by the driver.
    static RPlidarDriver * CreateDriver(_u32 drivertype = DRIVER_TYPE_SERIALPORT);//静态创建对象接口

    /// Dispose the RPLIDAR Driver Instance specified by the drv parameter
    /// Applications should invoke this interface when the driver instance is no longer used in order to free memory
    static void DisposeDriver(RPlidarDriver * drv);//处理驱动程序//静态接口函数析构RPlidar实例


public:
    /// Open the specified serial port and connect to a target RPLIDAR device
    ///
    /// \param port_path     the device path of the serial port
    ///        e.g. on Windows, it may be com3 or \\.\com10
    ///             on Unix-Like OS, it may be /dev/ttyS1, /dev/ttyUSB2, etc
    ///
    /// \param baudrate（波特率）      the baudrate used
    ///        For most RPLIDAR models, the baudrate should be set to 115200
    ///
    /// \param flag（标志）          other flags
    ///        Reserved for future use, always set to Zero
    virtual u_result connect(const char * port_path, _u32 baudrate, _u32 flag = 0) = 0;//设备连接函数,调用时会默认停止电机旋转，测试时需要使用startMotor启动电机旋转

    /// Disconnect with the RPLIDAR and close the serial port（断开连接并关上串口端）
    virtual void disconnect() = 0;//断开连接

    /// Returns TRUE when the connection has been established（连接已建立）
    virtual bool isConnected() = 0;

    /// Ask the RPLIDAR core system to reset it self
    /// The host system can use the Reset operation to help RPLIDAR escape the self-protection mode.
    ///
    //  \param timeout       The operation timeout value (in millisecond) for the serial port communication                     
    virtual u_result reset(_u32 timeout = DEFAULT_TIMEOUT) = 0;//超时重置

    /// Retrieve（恢复） the health status of the RPLIDAR
    /// The host system can use this operation to check whether RPLIDAR is in the self-protection mode.
    ///
    /// \param health        The health status info returned from the RPLIDAR
    ///
    /// \param timeout       The operation timeout value (in millisecond) for the serial port communication     
    virtual u_result getHealth(rplidar_response_device_health_t & health, _u32 timeout = DEFAULT_TIMEOUT) = 0;//获取 RPLIDAR 设备的健康状态
///
    /// Get the device information of the RPLIDAR include the serial number, firmware version, device model etc.
    ///
    /// \param info          The device information returned from the RPLIDAR
    ///
    /// \param timeout       The operation timeout value (in millisecond) for the serial port communication  
    virtual u_result getDeviceInfo(rplidar_response_device_info_t & info, _u32 timeout = DEFAULT_TIMEOUT) = 0;//获取 RPLIDAR 设备序列号、固件版本等信息

    /// Get the sample（样本） duration（持续时间） information of the RPLIDAR.
    ///
    /// \param rateInfo      The sample duration information returned from the RPLIDAR
    ///
    /// \param timeout       The operation timeout value (in millisecond) for the serial port communication
    virtual u_result getSampleDuration_uS(rplidar_response_sample_rate_t & rateInfo, _u32 timeout = DEFAULT_TIMEOUT) = 0;//获取 RPLIDAR 分别在标准 Scan 以及 ExpressScan 模式下单次激光采样的用时。 单位为微秒(uS)
    
    /// Set the RPLIDAR's motor pwm when using accessory board, currently valid for A2 only.
    ///
    /// \param pwm（脉宽）         The motor（电机） pwm value would like to set
    virtual u_result setMotorPWM(_u16 pwm) = 0;//向开发套件的 USB 附件板发送特定的 PWM 占空比,控制RPLIDAR 扫描电机转速

    /// Start RPLIDAR's motor when using accessory（附件） board
    virtual u_result startMotor() = 0;//启动电机

    /// Stop RPLIDAR's motor when using accessory board
    virtual u_result stopMotor() = 0;//停止电机

    /// Check whether the device support motor control.
    /// Note: this API will disable grab.
    ///
    /// \param support       Return the result.
    /// \param timeout       The operation timeout value (in millisecond) for the serial port communication.
    virtual u_result checkMotorCtrlSupport(bool & support, _u32 timeout = DEFAULT_TIMEOUT) = 0;//检测附件板是否支持电机 PWM 控制。

    /// Calcuate（计算） RPLIDAR's current scanning frequency from the given scan data
    /// Please refer to the application note doc for details
    /// Remark: the calcuation will be incorrect if the specified scan data doesn't contains enough data
    ///
    /// \param inExpressMode Indicate whether the RPLIDAR is in express mode（表达模式）
    ///
    /// \param count         The number of sample nodes inside the given buffer（缓冲区）
    ///
    /// \param frequency     The scanning frequency (in HZ) calcuated by the interface.
    ///
    /// \param is4kmode      Return whether the RPLIDAR is working on 4k sample rate mode.
    virtual u_result getFrequency(bool inExpressMode, size_t count, float & frequency, bool & is4kmode) = 0;//从实现抓取的一圈扫描数据序列计算 RPLIDAR 的转速
    /// Ask the RPLIDAR core system to enter the scan mode(Normal/Express, Express mode is 4k mode)
    /// A background thread（后台线程） will be created by the RPLIDAR driver to fetch（获取） the scan data continuously.
    /// User Application（应用） can use the grabScanData() interface to retrieved（恢复） the scan data cached（隐藏） previous by this background thread.
    ///
    /// \param force         Force the core system to output scan data regardless whether the scanning motor is rotating or not.（旋转与否）
    ///
    /// \param autoExpressMode Force the core system to trying express mode first, if the system does not support express mode, it will use normal mode.
    ///
    /// \param timeout       The operation timeout value (in millisecond) for the serial port communication.
    virtual u_result startScan(bool force = false, bool autoExpressMode = true) = 0;
    virtual u_result startScanNormal(bool force, _u32 timeout = DEFAULT_TIMEOUT) = 0;
    virtual u_result startScanExpress(bool fixedAngle, _u32 timeout = DEFAULT_TIMEOUT) = 0;

    /// Check whether the device support express mode.
    ///
    /// \param support       Return the result.
    ///
    /// \param timeout       The operation timeout value (in millisecond) for the serial port communication.
    virtual u_result checkExpressScanSupported(bool & support, _u32 timeout = DEFAULT_TIMEOUT) = 0;

    /// Ask the RPLIDAR core system to stop the current scan operation and enter idle state（空闲状态）. The background thread will be terminated（终止）
    ///
    /// \param timeout       The operation timeout value (in millisecond) for the serial port communication
    virtual u_result stop(_u32 timeout = DEFAULT_TIMEOUT) = 0;


    /// Wait and grab a complete 0-360 degree scan data previously received.
    /// The grabbed scan data returned by this interface always has the following charactistics:
    ///
    /// 1) The first node of the grabbed data array (nodebuffer[0]) must be the first sample of a scan, i.e. the start_bit == 1
    /// 2) All data nodes are belong to exactly ONE complete 360-degrees's scan
    /// 3) Note, the angle data in one scan may not be ascending（上升）. You can use API（应用程序界面） ascendScanData to reorder the nodebuffer.
    ///
    /// \param nodebuffer（存储扫描数据的缓冲区 ）    Buffer provided by the caller application to store the scan data
    ///
    /// \param count          The caller must initialize this parameter to set the max data count of the provided buffer (in unit of rplidar_response_measurement_node_t).
    ///                       Once the interface returns, this parameter will store the actual received data count.
    ///
    /// \param timeout        Max duration allowed to wait for a complete scan data, nothing will be stored to the nodebuffer if a complete 360-degrees' scan data cannot to be ready timely.
    ///
    /// The interface will return RESULT_OPERATION_TIMEOUT to indicate that no complete 360-degrees' scan can be retrieved withing the given timeout duration（持续时间）.
    ///
    /// \The caller application can set the timeout value to Zero(0) to make this interface always returns immediately to achieve non-block operation.
    virtual u_result grabScanData(rplidar_response_measurement_node_t * nodebuffer, size_t & count, _u32 timeout = DEFAULT_TIMEOUT) = 0;

    /// Ascending the scan data according to the angle value in the scan.
    ///
    /// \param nodebuffer     Buffer provided by the caller application to do the reorder. Should be retrived（索取） from the grabScanData
    ///
    /// \param count          The caller must initialize this parameter to set the max data count of the provided buffer (in unit of rplidar_response_measurement_node_t).
    ///                       Once the interface returns, this parameter will store the actual received data count.
    /// The interface will return RESULT_OPERATION_FAIL when all the scan data is invalid.
    virtual u_result ascendScanData(rplidar_response_measurement_node_t * nodebuffer, size_t count) = 0;

protected:
    RPlidarDriver() {}
    virtual ~RPlidarDriver() {}//此函数将在源文件中使用但不在此类中使用
};

}}}

（4）rptypes.h

#pragma once


#ifdef _WIN32

//fake stdint.h for VC only

typedef signed   char     int8_t;
typedef unsigned char     uint8_t;

typedef __int16           int16_t;
typedef unsigned __int16  uint16_t;

typedef __int32           int32_t;
typedef unsigned __int32  uint32_t;

typedef __int64           int64_t;
typedef unsigned __int64  uint64_t;

#else

#include <stdint.h>//定义int8 uint8等类型

#endif


//based on stdint.h
typedef int8_t         _s8;
typedef uint8_t        _u8;

typedef int16_t        _s16;
typedef uint16_t       _u16;

typedef int32_t        _s32;
typedef uint32_t       _u32;

typedef int64_t        _s64;
typedef uint64_t       _u64;

#define __small_endian

#ifndef __GNUC__
#define __attribute__(x)
#endif


// The _word_size_t uses actual data bus width of the current CPU
#ifdef _AVR_
typedef _u8            _word_size_t;
#define THREAD_PROC    
#elif defined (WIN64)
typedef _u64           _word_size_t;
#define THREAD_PROC    __stdcall
#elif defined (WIN32)
typedef _u32           _word_size_t;
#define THREAD_PROC    __stdcall
#elif defined (__GNUC__)
typedef unsigned long  _word_size_t;
#define THREAD_PROC   
#elif defined (__ICCARM__)
typedef _u32            _word_size_t;
#define THREAD_PROC  
#endif


typedef uint32_t u_result;

#define RESULT_OK              0
#define RESULT_FAIL_BIT        0x80000000
#define RESULT_ALREADY_DONE    0x20
#define RESULT_INVALID_DATA    (0x8000 | RESULT_FAIL_BIT)
#define RESULT_OPERATION_FAIL  (0x8001 | RESULT_FAIL_BIT)
#define RESULT_OPERATION_TIMEOUT  (0x8002 | RESULT_FAIL_BIT)
#define RESULT_OPERATION_STOP    (0x8003 | RESULT_FAIL_BIT)
#define RESULT_OPERATION_NOT_SUPPORT    (0x8004 | RESULT_FAIL_BIT)
#define RESULT_FORMAT_NOT_SUPPORT    (0x8005 | RESULT_FAIL_BIT)
#define RESULT_INSUFFICIENT_MEMORY   (0x8006 | RESULT_FAIL_BIT)

#define IS_OK(x)    ( ((x) & RESULT_FAIL_BIT) == 0 )
#define IS_FAIL(x)  ( ((x) & RESULT_FAIL_BIT) )

typedef _word_size_t (THREAD_PROC * thread_proc_t ) ( void * );

(5)rplidar.h

#pragma once

#include "rptypes.h"
#include "rplidar_protocol.h"
#include "rplidar_cmd.h"

#include "rplidar_driver.h"

#define RPLIDAR_SDK_VERSION  "1.5.7"

由此可见，在编程rplidar的相关代码时只需调用rplidar.h即可，但必须清楚其中所包含的其他头文件所含参数的意义，不然无法看懂相关C++代码文件。。。