Current CDC block is inefficient for connecting clock domains using synchronous clocks with different frequencies

[wzab]

Current CDC block https://github.com/wzab/agwb/blob/9070a2d2f3c2fafb12ff9276e5b36311eea217b9/hdl/wb_cdc/wb_cdc.vhd is optimized for transfering single accesses between domains driven by asynchronous clocks.
Often it is necessary to transfer accesses between domains where the clocks are synchronous, and the first one has a frequency N times higher then the second one: f_CLK1 = N * f_CLK2 .
In such a case the domain crossing circuit may be significantly simpler. It is necessary to design the CDC for both possible cases:

• f_CLKmaster = N * f_CLKslave
• f_CLKslave = N * f_CLKmaster