In this section, we will categorize the members and methods of CGPortHole into four categories: buffer management, buffer embedding, geodesic switching, and others.
int offset;This is a protected member used for indexing into the buffer connected to this port.
The methods described in this subsection are all public:
unsigned bufPos() const;Returns
offset, the offset position in the buffer.
virtual int bufSize() const;Both methods returns the size of buffer connected to this porthole. In the CGPortHole base class, they call the corresponding methods of class CGGeodesic. Recall that the second method returns 0 when it is a Fork output. If a porthole is at the wormhole boundary, both return the product of the sample rate and the repetition count of the parent star.
virtual int localBufSize() const;
virtual void advance();This method is called by
CGStar::advance(). After the parent star is executed, we advance the offset by the number of samples produced or consumed. The offset is calculated modulo the buffer size, so that it is wrapped around if it reaches the boundary of the buffer.
embedding: the larger input buffer is embedding the smaller output buffer, and the smaller output buffer is embedded in the larger input buffer. Unlike the Fork buffer, the sizes of input and output embedded buffers are different from each other. Therefore, we must specify at which position the embedded buffer begins in the larger embedding buffer. We use this embedding relationship to implement Spread and Collect stars in the CGC domain, without increasing the buffer requirements. For example, the output buffers of a Spread star are embedded in the input buffer of the star, starting from different offsets.
CGPortHole* embeddedPort;These are protected members to specify embedding relationships. The first one points to the embedding port which this PortHole is embedded in. The second member indicates the starting offset of embedding. The last member indicates whether this porthole is an embedding port or not.
int embeddingFlag;
The following are public methods related to embedding.
CGPortHole* embedded();These methods return the protected members described above, respectively.
int whereEmbedded();
int embedding();
void embed(CGPortHole& p, int i=-1);This method establishes an embedding relationship between this port and the argument port
p. This porthole becomes an embedding porthole, and the argument porthole becomes an embedded porthole. The second argument specifies the starting offset.
void embedHere(int offset);This method, when called on an embedded porthole, changes the starting offset its embedded buffer in the embedding buffer.
virtual void switchGeo(Geodesic* g);Both methods set the Geodesic pointer to the argument
virtual void revertGeo(Geodesic* g);
g. There is a flag to indicate whether this port has switched its Geodesic or not. The first method sets the flag to TRUE while the second method resets the flag to FALSE. Both methods are virtual since in derived classes we may need to redefine the behavior, perhaps by saving the original Geodesic, which is not the default behavior. The flag is queried by:
int switched() const;If the Geodesic is switched in this port, we have to reset the geodesic pointer of this port to
NULL in the destructor in order to prevent attempts to delete the same Geodesic multiple times. Also, we have to make sure that both ends of a Geodesic do not switch their Geodesic, in order to prevent orphaning the geodesic and causing a memory leak.
forkDests list and remove the pointer to this porthole from the forkDests list of the forkSrc port. All members described in the subsection are public.
CGGeodesic& cgGeo() const;This method returns a reference to the Geodesic after type casting.
void forceSendData();These methods put and get samples to and from the Geodesic at the wormhole boundary. They are used when the inside code generation domain communicates by the wormhole mechanism.
void forceGrabData();
Class MultiCGPort is derived from class MultiDFPort. It has a protected member
forkSrc to point to the Fork input if its parent star is a Fork star. It has a default destructor.
CGPortHole* forkSrc;There are two public methods related to this protected member:
void setForkBuf(CGPortHole& p);The first method sets
void forkProcessing(CGPortHole& p);
forkSrc to point to the argument port. The second method sets the forkSrc pointer of the argument port to point to the forkSrc of this MultiCGPort.Two classes are publicly derived from MultiCGPort: MultiInCGPort and MultiOutCGPort. They both have the following public method:
PortHole& newPort();This method creates an InCGPort or an OutCGPort depending on whether it is an input or an output MultiCGPort.