3 ms·
Or Verilog, or any hardware description language that runs events on an event queue while explicitly keeping track of time.
by sketerpot 16y ago
Or Verilog, or any hardware description language that runs events on an event queue while explicitly keeping track of time.
- dkersten 16y agoOr any other dataflow language
- mr_seeker 16y ago"Keeping track of time" is not the right word. What I learned at school is that the VHDL design does all the operations at once, and the software that programs the hardware times everything so that the output of every operation is at the same clockpulse. This means that a=b+c is done at the same clockpulse as d=e+f.
- sketerpot 16y agoVHDL can model delays for operations, so that any events which they trigger are not triggered until after a delay. This is useful for modeling things like logic gates, which have a propagation delay associated with them. If you're using VHDL for design automation, and you're going to synthesize it to hardware, then the synthesis program does logic mapping to whatever technology (standard cells, FPGA blocks, etc.) is being used, figures out the logic and interconnect delays, and tries to satisfy the requirement that everything be ready when the clock ticks, while allowing a reasonable clock frequency. The way that VHDL handles both uses can be a little confusing.