Receiver based communication permission token allocation

Apparatus for processing data, said apparatus comprising:

• master means for initiating messages;
• slave means for responding to messages received from said master means;
• and
• communication means for providing communication of messages between said master means and said slave means;
• wherein
• said slave means is associated with a predetermined number permission tokens, said predetermined number of permission tokens being equal to a maximum number of concurrently pending messages that can be accepted for processing from said communication means by said slave means under control of said permission tokens;
• said slave means transmits said permission tokens to said master means via said communication means;
• said master means takes exclusive temporary possession of a permission token received via said communication means such that said permission token is no longer available for possession by any other master means;
• said master means initiates a message to said slave means only when said master means has said exclusive temporary possession of said permission token;
• and
• said master means relinquishes said exclusive temporary possession of said permission token after said message has been completed.

A method of processing data, said method comprising the steps of:

• initiating messages with a master device;
• responding with a slave device to messages received from said master device;
• and
• providing communication of messages via communication circuitry between said master means and said slave means;
• wherein
• said slave device is associated with a predetermined number permission tokens, said predetermined number of permission tokens being equal to a maximum number of concurrently pending messages that can be accepted for processing from said communication circuitry by said slave device under control of said permission tokens;
• said slave device transmits said permission tokens to said master device via said communication circuitry;
• said master device takes exclusive temporary possession of a permission token received via said communication circuitry such that said permission token is no longer available for possession by any other master devices;
• said master device initiates a message to said slave device only when said master device has said exclusive temporary possession of said permission token;
• and
• said master device relinquishes said exclusive temporary possession of said permission token after said message has been completed.