OPNET学习笔记

OPNET学习笔记simple_source模块的功能是按照配置产生包，包括不同的包格式和产生速率，也是比较简单的进程模型。

参考了《opnet process model：simple_source分析》/ebinghaus/blog/item/c7cade9228876c83a877a405.html 该模块有4个local statistic，注意有5个model attribute，分别是Packet Interarrival Time，Packet Size，Packet Format，Start Time，Stop Time，这些是在使用该模块时需要配置的，当然也可以使用默认配置。

状态机也很简单：在header block中定义了/* Include files. */#include <oms_dist_support.h>//注意该模块使用了外部文件《oms_dist_support》和《oms_string_support》/* Special attribute values. */#define SSC_INFINITE_TIME -1.0//定义无穷大时间为-1/* Interrupt code values. *///注意这里的中断代码是自定义的，为了在产生自中断是使用#define SSC_START 0#define SSC_GENERATE 1#define SSC_STOP 2/* Node configuration constants. */#define SSC_STRM_TO_LOW 0//发送的stream index，默认的，该模块只有一个stream连接，所以不需要动态获取stream index/* Macro definitions for state transitions.*///转换条件为中断代码是自定义的常量：#define START (intrpt_code == SSC_START)#define DISABLED (intrpt_code == SSC_STOP)#define STOP (intrpt_code == SSC_STOP)#define PACKET_GENERATE (intrpt_code == SSC_GENERATE)/* Function prototypes. */static void ss_packet_generate (void);//产生包的函数，在function block中定义一，INIT的入口代码：/* At this initial state, we read the values of source attributes *//* and schedule a selt interrupt that will indicate our start time *//* for packet generation. *//* Obtain the object id of the surrounding module. */own_id = op_id_self ();//首先得到surrounding objid，应该是自己的objid，后面根据objid获取对象的属性/* Read the values of the packet generation parameters, i.e. the *//* attribute values of the surrounding module. *///用op_ima_obj_attr_get()得到对象的属性的值，是产生包的参数。

注意interarrival_str和size_str是临时变量，还是char数组类型。

op_ima_obj_attr_get (own_id, "Packet Interarrival Time", interarrival_str);op_ima_obj_attr_get (own_id, "Packet Size", size_str);op_ima_obj_attr_get (own_id, "Packet Format", format_str);op_ima_obj_attr_get (own_id, "Start Time", &start_time);op_ima_obj_attr_get (own_id, "Stop Time", &stop_time);/* Load the PDFs that will be used in computing the packet *//* interarrival times and packet sizes. *///装入PDF，用于前两个参数，得到包产生和包大小的分布，函数是oms_dist_load_from_string()，这样很方便的使用string类型的参数。

//获得的是分布函数的句柄，注意两个句柄都是state variable，类型为Omst_dist_handle。

interarrival_dist_ptr = oms_dist_load_from_string (interarrival_str);pksize_dist_ptr = oms_dist_load_from_string (size_str);/* Verify the existence of the packet format to be used for generated packets. */if (strcmp (format_str, "NONE") == 0)//检查是否是无格式包{/* We will generate unformatted packets. Set the flag. */generate_unformatted = OPC_TRUE;}else{/* We will generate formatted packets. Turn off the flag. */generate_unformatted = OPC_FALSE;//不是无格式包/* Get the list of all available packet formats. *///用prg_tfile_name_list_get()得到所有可用的包格式pk_format_names_lptr = prg_tfile_name_list_get (PrgC_Tfile_Type_Packet_Format); /* Search the list for the requested packet format. */format_found = OPC_FALSE;for (i = prg_list_size (pk_format_names_lptr); ((format_found == OPC_FALSE) && (i > 0)); i--){/* Access the next format name and compare with requested format name */ found_format_str = (char *) prg_list_access (pk_format_names_lptr, i - 1);if (strcmp (found_format_str, format_str) == 0)format_found = OPC_TRUE;//找到了需求的包格式}if (format_found == OPC_FALSE){/* The requested format does not exist. Generate unformatted packets. */generate_unformatted = OPC_TRUE;/* Display an appropriate warning. */op_prg_odb_print_major ("Warning from simple packet generator model (simple_source):","The specified packet format", format_str,"is not found. Generating unformatted packets instead.", OPC_NIL);}/* Destroy the lits and its elements since we don't need it *//* anymore. */prg_list_free (pk_format_names_lptr);prg_mem_free (pk_format_names_lptr);}/* Make sure we have valid start and stop times, i.e. stop time is not earlier than start time. */if ((stop_time <= start_time) && (stop_time != SSC_INFINITE_TIME))//开始/结束时间不合法，设置开始仿真时间为无穷大{/* Stop time is earlier than start time. Disable the source. */start_time = SSC_INFINITE_TIME;/* Display an appropriate warning. */op_prg_odb_print_major ("Warning from simple packet generator model (simple_source):","Although the generator is not disabled (start time is set to a finite value),","a stop time that is not later than the start time is specified.","Disabling the generator.", OPC_NIL);}/* Schedule a self interrupt that will indicate our start time for *//* packet generation activities. If the source is disabled, *//* schedule it at current time with the appropriate code value. *///产生自中断，以指示开始产生包的时间，如果停止产生包时刻小于开始产生包的时刻（这时开始产生包的时间是无限大）在当前仿真时刻产生中断号为SSC_STOP中断if (start_time == SSC_INFINITE_TIME){op_intrpt_schedule_self (op_sim_time (), SSC_STOP);//马上给出自中断}else{op_intrpt_schedule_self (start_time, SSC_START);//自中断，在开始时间，中断号为SSC_START/* In this case, also schedule the interrupt when we will stop *//* generating packets, unless we are configured to run until *//* the end of the simulation. */if (stop_time != SSC_INFINITE_TIME){op_intrpt_schedule_self (stop_time, SSC_STOP);//当结束时间不是无限大时，在结束时间产生自中断，中断号为SSC_STOP}next_intarr_time = oms_dist_outcome (interarrival_dist_ptr);//通过分布函数句柄计算产生下一个包的时间间隔，这里是state variable/* Make sure that interarrival time is not negative. In that case it will be set to 0.*/ if (next_intarr_time <0){next_intarr_time = 0.0;//保证间隔时间不小于0}}/* Register the statistics that will be maintained by this model. *///注册局部统计量，返回局部统计量的句柄bits_sent_hndl = op_stat_reg ("Generator.Traffic Sent (bits/sec)", OPC_STAT_INDEX_NONE, OPC_STAT_LOCAL);packets_sent_hndl = op_stat_reg ("Generator.Traffic Sent (packets/sec)", OPC_STAT_INDEX_NONE, OPC_STAT_LOCAL);packet_size_hndl = op_stat_reg ("Generator.Packet Size (bits)", OPC_STAT_INDEX_NONE, OPC_STAT_LOCAL);interarrivals_hndl = op_stat_reg ("Generator.Packet Interarrival Time (secs)", OPC_STAT_INDEX_NONE, OPC_STAT_LOCAL);二，由于初始状态是非强制状态，进程执行完入口代码后，停留在该状态等待中断触发转移状态,仿真时刻到10s（属性start_time设置的值）时将产生中断号为SSC_START中断，中断产生后将首先执行当前状态的出口代码，初始状态的出口代码如下：intrpt_code = op_intrpt_code ();//得到当前的中断代码这时条件START满足，进程将从初始状态转换到generate状态，转移时首先执行转移函数ss_packet_generate (void)，在function block中定义的转移函数如下：static void ss_packet_generate (void){Packet* pkptr;double pksize;/** This function creates a packet based on the packet generation **//** specifications of the source model and sends it to the lower layer. **/FIN (ss_packet_generate ());/* Generate a packet size outcome. */pksize = (double) ceil (oms_dist_outcome (pksize_dist_ptr));//通过分布函数句柄得到包大小，再通过ceil()函数向上舍入，得到包大小/* Create a packet of specified format and size. */if (generate_unformatted == OPC_TRUE){/* We produce unformatted packets. Create one. */pkptr = op_pk_create (pksize);//使用op_pk_creat()函数产生无格式包}else{/* Create a packet with the specified format. */pkptr = op_pk_create_fmt (format_str);//使用op_pk_creat_fmt()函数产生有格式包op_pk_total_size_set (pkptr, pksize);//置有格式包的总大小}/* Update the packet generation statistics. *///通过局部统计量句柄更新统计量，注意xxx/sec的量都是在更新后马上清零op_stat_write (packets_sent_hndl, 1.0);op_stat_write (packets_sent_hndl, 0.0);op_stat_write (bits_sent_hndl, (double) pksize);op_stat_write (bits_sent_hndl, 0.0);op_stat_write (packet_size_hndl, (double) pksize);op_stat_write (interarrivals_hndl, next_intarr_time);/* Send the packet via the stream to the lower layer. */op_pk_send (pkptr, SSC_STRM_TO_LOW);//发送包到定义好的stream index，默认为0FOUT;三，执行完转移函数后将跳到generate状态，并首先执行入口代码，如下：/* At the enter execs of the "generate" state we schedule the *//* arrival of the next packet. */next_intarr_time = oms_dist_outcome (interarrival_dist_ptr);//通过分布函数句柄得到下一个包的产生时间间隔/* Make sure that interarrival time is not negative. In that case it will be set to 0.*/if (next_intarr_time <0){next_intarr_time = 0;}//在当前时间+间隔时间后，产生自中断，中断号为SSC_GENERATE，注意返回值为Evhandle类型next_pk_evh = op_intrpt_schedule_self (op_sim_time () + next_intarr_time, SSC_GENERATE);四，执行完入口代码后，进程将停留在generate状态等待中断，当下一个中断发生，进行状态转换，首先执行generate状态的出口代码：intrpt_code = op_intrpt_code ();//得到中断号然后判断转移条件。