Nokia Corporation

Juhani Vehvilainen

Pasi Kolinummi

Mika Koikkalainen

A device comprises an integrated circuit having first and second domains, the first domain having a first clock boundary module; and the second domain having a second clock boundary module. The first clock boundary module comprises: a buffer, for storing data for transfer to the second domain; and a first controller operable to send a first control signal to the second clock boundary module via a first synchronizer, the first control signal indicating the presence of a packet of data in a first storage location of the buffer. One of the first and second clock boundary modules comprises a multiplexer having an input connected to an output of the buffer and an output connected to circuitry forming part of the second domain. The second clock boundary module comprises: a second controller, operable in response to receiving the first control signal to control transfer of said data from the buffer by the multiplexer, and to send a second control signal to the first controller via a second synchronizer, the second control signal indicating transfer of said data.

Transferring data between asynchronous clock domains

The invention relates to a method in a hardware semaphore lock (L&#x2013;LN) intended for a multi-processor system, which semaphore lock (L&#x2013;LN) protects a shared resource (R&#x2013;RN) in connection with the system in such a way that only a process which has reserved the semaphore lock (L&#x2013;LN) and has thus become a holder of the lock, has access to use the resource protected by the lock. The semaphore lock (L&#x2013;LN) is reserved by a single read operation of a memory location representing the semaphore lock by the process software. The read operation returns to the process the number of vacant holder positions, i.e. keyholes vacant at the time of the reservation of the lock. The semaphore lock does not require the support of the system for atomic read/write operations.

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Tampere, Finland

Juhani Vehvilainen