Apparatus and method for accessing vertex data

A vertex data queue controller, comprising:

• a limit counter to record the number of requests issued by the interface controller;
• an available counter to record the amount of return vertex data in the vertex data queue not yet read;
• an index comparator unit to receive a vertex index for finding out whether the vertex index is the same as any one index in an vertex index register, and reporting a corresponding result;
• a request controller coupled to the index comparator unit to receive the result, determine to send the vertex data request to the interface controller according to the result and the value of the limit counter, and store the result into a reference register, thus the interface controller fetches a vertex data from a system memory according to the vertex data request and stores the vertex data into an vertex data queue;
• and
• an access controller to read the result stored in the reference register and access the vertex data from the vertex data queue according to the result and the value of the available counter if the vertex data read signal is received.

A vertex data access method, comprising the steps of:

• receiving a vertex index;
• determining to send a vertex data request corresponding to the vertex index according to the vertex index for informing an interface controller to fetch vertex data from a system memory according to the vertex data request and store the vertex data into a vertex data queue;
• monitoring the state of the vertex data queue;
• receiving a vertex data read signal;
• and
• accessing the vertex data from the vertex data queue according to the state of the vertex data queue.