RDM Helper functions

Detailed Description

RDM Helper Functions.

Files
file	rdm_util.h
	RDM Helper functions.

Functions
static int	RDMUtil_UIDCompare (const uint8_t *uid1, const uint8_t *uid2)
	Compare two UIDs. More...
bool	RDMUtil_RequiresAction (const uint8_t our_uid[UID_LENGTH], const uint8_t uid[UID_LENGTH])
	Check if a RDM request sent to a UID requires us to take action. More...
bool	RDMUtil_IsUnicast (const uint8_t uid[UID_LENGTH])
bool	RDMUtil_VerifyChecksum (const uint8_t *frame, unsigned int size)
	Verify the checksum of an RDM frame. More...
int	RDMUtil_AppendChecksum (uint8_t *frame)
	Append the RDM checksum for a frame. More...
unsigned int	RDMUtil_StringCopy (char *dst, unsigned int dest_size, const char *src, unsigned int max_size)
	Copy a string from one location to another. More...
unsigned int	RDMUtil_SafeStringLength (const char *str, unsigned int max_size)
	Calculate the size of the string, but never scan beyond max_size. More...
void	RDMUtil_UpdateSensor (SensorData *sensor, uint8_t recorded_value_support, int16_t new_value)
	Update the value of a sensor, setting the lowest / highest values if appropriate. More...

Function Documentation

int RDMUtil_AppendChecksum

(

uint8_t *

frame

)

Append the RDM checksum for a frame.

Parameters

frame

The RDM frame.

Returns

The size of the complete RDM frame.

Precondition

The frame points to a well formed RDM message.

bool RDMUtil_RequiresAction	(	const uint8_t	our_uid[UID_LENGTH],
		const uint8_t	uid[UID_LENGTH]
	)

Check if a RDM request sent to a UID requires us to take action.

Parameters

our_uid	The UID of the responder to check
uid	The UID to check.

Returns

true if we should process the RDM request, false otherwise.

Action is required if any of the following is true:

• The UID exactly matches our UID.
• The UID is the broadcast UID (ffff:ffffffff)
• The UID is a vendorcast UID, and the manufacturer ID matches ours.

unsigned int RDMUtil_SafeStringLength	(	const char *	str,
		unsigned int	max_size
	)

Calculate the size of the string, but never scan beyond max_size.

Parameters

str	The string
max_size	The max size of the string.

Returns

The size of the string, at most max_size.

Since RDM strings may be missing the NULL terminator, this should be used when determining string lengths.

unsigned int RDMUtil_StringCopy	(	char *	dst,
		unsigned int	dest_size,
		const char *	src,
		unsigned int	max_size
	)

Copy a string from one location to another.

Parameters

dst	The location to copy to.
dest_size	The maximum number of bytes to copy to dst.
src	The location to copy from.
max_size	The maximum number of characters to copy.

Returns

The size of the final string, excluding any NULL if there is one.

RDM strings are not required to have a NULL terminator, which means we can't use the usual string functions like strncpy(). This function should be used when copying strings.

static int RDMUtil_UIDCompare ( const uint8_t *  uid1, const uint8_t *  uid2  )

inlinestatic

Compare two UIDs.

Parameters

uid1	The first uid.
uid2	The second uid.

Returns

< 0 if uid1 < uid2, 0 if the UIDs are the same, > 0 if uid1 > uid2.

void RDMUtil_UpdateSensor	(	SensorData *	sensor,
		uint8_t	recorded_value_support,
		int16_t	new_value
	)

Update the value of a sensor, setting the lowest / highest values if appropriate.

Parameters

sensor	The sensor to update
recorded_value_support	The bitfield to check if the sensor supports recording.
new_value	The new value of the sensor.

bool RDMUtil_VerifyChecksum	(	const uint8_t *	frame,
		unsigned int	size
	)

Verify the checksum of an RDM frame.

Parameters

frame	The frame data, beginning with the start code.
size	The size of the frame data.

Returns

True if the checksum was correct, false otherwise.

Frame sizes less than the minimum RDM frame size (26 bytes) will always return false.