FreeRTOS-Kernel/Demo/Common/Utils/CommandInterpreter.c

/*
    FreeRTOS V7.0.1 - Copyright (C) 2011 Real Time Engineers Ltd.
	

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    the terms of the GNU General Public License (version 2) as published by the
    Free Software Foundation AND MODIFIED BY the FreeRTOS exception.
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*/

#include "FreeRTOS.h"
#include "task.h"
#include "CommandInterpreter.h"

typedef struct xCOMMAND_INPUT_LIST
{
	const xCommandLineInput *pxCommandLineDefinition;
	struct xCOMMAND_INPUT_LIST *pxNext;
} xCommandLineInputListItem;

/*
 * The callback function that is executed when "help" is entered.  This is the
 * only default command that is always present.
 */
static const signed char *prvHelpCommand( void );

/* The definition of the "help" command.  This command is always at the front
of the list of registered commands. */
static const xCommandLineInput xHelpCommand = 
{
	"help",
	"help: Lists all the registered commands\r\n",
	prvHelpCommand
};

/* The definition of the list of commands.  Commands that are registered are
added to this list. */
static xCommandLineInputListItem xRegisteredCommands =
{	
	&xHelpCommand,	/* The first command in the list is always the help command, defined in this file. */
	NULL			/* The next pointer is initialised to NULL, as there are no other registered commands yet. */
};

/*-----------------------------------------------------------*/

portBASE_TYPE xCmdIntRegisterCommand( const xCommandLineInput * const pxCommandToRegister )
{
static xCommandLineInputListItem *pxLastCommandInList = &xRegisteredCommands;
xCommandLineInputListItem *pxNewListItem;
portBASE_TYPE xReturn = pdFAIL;

	/* Check the parameter is not NULL. */
	configASSERT( pxCommandToRegister );

	/* Create a new list item that will reference the command being registered. */
	pxNewListItem = ( xCommandLineInputListItem * ) pvPortMalloc( sizeof( xCommandLineInputListItem ) );
	configASSERT( pxNewListItem );

	if( pxNewListItem != NULL )
	{
		taskENTER_CRITICAL();
		{
			/* Reference the command being registered from the newly created 
			list item. */
			pxNewListItem->pxCommandLineDefinition = pxCommandToRegister;

			/* The new list item will get added to the end of the list, so 
			pxNext has nowhere to point. */
			pxNewListItem->pxNext = NULL;

			/* Add the newly created list item to the end of the already existing
			list. */
			pxLastCommandInList->pxNext = pxNewListItem;

			/* Set the end of list marker to the new list item. */
			pxLastCommandInList = pxNewListItem;
		}
		
		xReturn = pdPASS;
	}

	return xReturn;
}
/*-----------------------------------------------------------*/

const signed char *pcCmdIntProcessCommand( const signed char * const pcCommandInput )
{
static const xCommandLineInputListItem *pxCommand = NULL;
signed const char *pcReturn = NULL;

	/* Note:  This function is not re-entrant.  It must not be called from more
	thank one task. */

	if( pxCommand == NULL )
	{
		/* Search for the command string in the list of registered commands. */
		for( pxCommand = &xRegisteredCommands; pxCommand != NULL; pxCommand = pxCommand->pxNext )
		{
			if( strcmp( ( const char * ) pcCommandInput, ( const char * ) pxCommand->pxCommandLineDefinition->pcCommand ) == 0 )
			{
				/* The command has been found, the loop can exit so the command
				can be executed. */
				break;
			}
		}
	}

	if( pxCommand != NULL )
	{
		pcReturn = pxCommand->pxCommandLineDefinition->pxCommandInterpreter();

		/* If no strings were returned, then all the strings that are going to
		be returned by the current command have already been returned, and
		pxCommand can be reset to NULL ready to search for the next entered
		command. */
		if( pcReturn == NULL )
		{
			pxCommand = NULL;
		}
	}
	else
	{
		pcReturn = "Command not recognised.  Available commands are listed below.\r\n\r\n";

		/* Print out the help string. */
		pxCommand = &xRegisteredCommands;
	}

	return pcReturn;
}
/*-----------------------------------------------------------*/

static const signed char *prvHelpCommand( void )
{
static const xCommandLineInputListItem * pxCommand = &xRegisteredCommands;
signed const char *pcReturn;

	/* pxCommand will be NULL if all the commands in the list have already been
	returned. */
	if( pxCommand != NULL )
	{
		/* Return the next command help string, before moving the pointer on to
		the next command in the list. */
		pcReturn = pxCommand->pxCommandLineDefinition->pcHelpString;
		pxCommand = pxCommand->pxNext;
	}
	else
	{
		/* Reset the pointer back to the start of the list. */
		pxCommand = &xRegisteredCommands;

		/* Return NULL to show that there are no more strings to return. */
		pcReturn = NULL;
	}
	
	return pcReturn;
}