Contiki learning notes --- process structure, contiki --- process

Contiki learning notes --- process structure, contiki --- process

Process, literally, process, look at its structure

 1 struct process { 2       struct process *next; 3 #if PROCESS_CONF_NO_PROCESS_NAMES 4 #define PROCESS_NAME_STRING(process) "" 5 #else 6       const char *name; 7 #define PROCESS_NAME_STRING(process) (process)->name 8 #endif 9       PT_THREAD((* thread)(struct pt *, process_event_t, process_data_t));10       struct pt pt;11       unsigned char state, needspoll;12 };

Process indicates a process, which is a struct:

1. struct process * next; the first member * next has its own type and its name starts with "next". It is obviously prepared for the linked list, indicating that all processes will be stored in a linked list. 2. const char * name; this indicates the name of the Process, 3 ~ Row 8: when the global variable PROCESS_CONF_NO_PROCESS_NAMES, the name is null, indicating that the process has no name. This should be prepared for some special CPUs. Ignore it and we will have a name for all processes. # Define PROCESS_NAME_STRING (process)-> name defines a method PROCESS_NAME_STRING () using a macro. Its function is to return the name Member of this struct. This implementation method is quite interesting. It is totally different from C # in the two spiritual worlds, and we will be able to adapt more in the future. 3. PT_THREAD (* thread) (struct pt *, process_event_t, process_data_t); PT_THREAD in Pt. the h header file is defined as follows: # define PT_THREAD (name_args) char name_args substitutes the entire code into the macro definition and expands as follows: char (* thread) (struct pt *, process_event_t, process_data_t) thread is a function pointer pointing to a function that contains three parameters and returns a char type. What does this function do? Study later.
4. struct pt; the variable name and struct name are the same. The C language is really different, but this variable name is only valid in the structure. Let's take a look at the pt definition of the struct, or in the Pt. h header file.

1  struct pt {2         lc_t lc;3     };

What is lc_t? Continue tracing, typedef unsigned short lc_t; unsigned short type in the Lc-switch.h header file, just a number, an identifier. Why does the pt struct have only one member? Let's make it clear later. 5. unsigned char state. This indicates the state of the process. The three numbers are 0, 1, and 2. Macro definition, in the Process. c file

#define PROCESS_STATE_NONE           0#define PROCESS_STATE_RUNNING     1#define PROCESS_STATE_CALLED        2

These three statuses can only be explained when they are used. 6. unsigned char needspoll; indicates the process priority, which will be used later.