System-interaction calls

Invoke system calls. More...

Data Structures
struct	system_command

Macros
#define	SYSTEM_MAX_COMMAND_NAME_LENGTH   16
#define	SYSTEM_MAX_COMMANDS   16

Typedefs
typedef uint8_t	system_iterator
typedef uint8_t	exit_status_t
typedef struct system_command	system_command

Functions
void	system_init ()
bool	system_register_command (const char *, int(*)())
bool	system_deregister_command (const char *)
exit_status_t	system_exec (const char *, const char **)
system_command *	_system_command_from_name (const char *command_name)

Detailed Description

Invoke system calls.

Every language offers a 'system' call – pass it a string and the system interprets it. This is that library for this RTOS.

Author

Eric Crosson

Version

0.1

Date

2014

Precondition

None

Copyright

GNU Public License

Macro Definition Documentation

#define SYSTEM_MAX_COMMAND_NAME_LENGTH   16

Maximum length of a callable command.

Definition at line 14 of file system.h.

#define SYSTEM_MAX_COMMANDS   16

Maximum number of commands supported by the system.

Definition at line 17 of file system.h.

Referenced by _system_command_from_name(), system_init(), and system_register_command().

Typedef Documentation

typedef uint8_t exit_status_t

Type definition of an exit code.

Definition at line 24 of file system.h.

typedef struct system_command system_command

typedef uint8_t system_iterator

Iterator optimized for size that is guaranteed to be able to iterate over .

Definition at line 21 of file system.h.

Function Documentation

system_command* _system_command_from_name

(

const char *

command_name

)

For internal use only. This function returns a pointer to the registered to the command name .

Definition at line 58 of file system.c.

References strcmp(), and SYSTEM_MAX_COMMANDS.

Referenced by system_deregister_command(), and system_exec().

                                                                    {

    system_iterator i=0;
    while(i<SYSTEM_MAX_COMMANDS &&
          0 != strcmp(SYSTEM_COMMANDS[i].name, command_name)) {
        ++i;
    }
    return &SYSTEM_COMMANDS[i];
}

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bool system_deregister_command

(

const char *

)

Remove a command from the index of executable system commands.

Returns

True if command was successfully deregistered.

Definition at line 45 of file system.c.

References _system_command_from_name(), CDL_DELETE, CDL_PREPEND, and system_command::valid.

                                                         {

    /* Grab the structure of the command to deregister and invaldiate
     * the metadata. Move it from the registered to the unregistered
     * pile. */
    system_command* command = _system_command_from_name(command_name);
    command->valid = false;
    CDL_DELETE(registered_commands, command);
    CDL_PREPEND(unregistered_commands, command);
    return true;
}

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exit_status_t system_exec	(	const char *	,
		const char **
	)

Execute a system command.

Returns

The exit code of the executed command.

Bug:

Currently argument passing is not supported.

Definition at line 69 of file system.c.

References _system_command_from_name(), system_command::command, postpone_death, and system_command::valid.

Referenced by shell_execute_command().

                                                                       {

    system_command* sys_command = _system_command_from_name(command);
    if (sys_command->valid) {
    return sys_command->command(/*arguments*/);
    } else {
    /* TODO: determine what to do here */
    postpone_death();       /* plan a */
    return EXIT_FAILURE;    /* plan b */
    }
}

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void system_init

(

)

Initialize internal data structures.

Note

Ensure this method is called before any commands are registered.

Definition at line 19 of file system.c.

References CDL_PREPEND, and SYSTEM_MAX_COMMANDS.

Referenced by main().

                   {

    system_iterator i;
    /* All commands begin in the unregistered state */
    for(i=0; i<SYSTEM_MAX_COMMANDS; ++i) {
    CDL_PREPEND(unregistered_commands, &SYSTEM_COMMANDS[i]);
    }
}

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bool system_register_command	(	const char *	,
		int(*)()
	)

Register a command for later execution.

Returns

True if command was successfully registered.

Definition at line 29 of file system.c.

References CDL_DELETE, CDL_PREPEND, system_command::command, memset(), system_command::name, SYSTEM_MAX_COMMANDS, unregistered_commands, ustrcpy(), and system_command::valid.

Referenced by main().

                                                                        {

    /* Grab the first free command, move it from the unregisted to the
     * registered pile, and populate it with this function's
     * arguments */
    system_command* sys_command = unregistered_commands;
    CDL_DELETE(unregistered_commands, sys_command);
    CDL_PREPEND(registered_commands, sys_command);

    sys_command->valid = true;
    memset(sys_command->name, 0, SYSTEM_MAX_COMMANDS);
    ustrcpy(sys_command->name, command_name);
    sys_command->command = command;
    return true;
}

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