Verify Heir Conditional with airSlate SignNow

Verify heir conditional

another example is some data fetch unit so the input is the address to fetch the cache will be checked first and if there's a miss then it'll have to be fetched from external memory and the check requires that the latency from a request to memory in the case of a miss is four to six cycles so basically our problem is how do we not front whether the request will result in a miss or not so this is where we use data tagging we're gonna use one address bit here we choose arbitrarily bit 13 as an early decision of whether there will be a cache hit or miss if the bit is set bit 13 and it's a hit if the bit 13 is zero that means a miss so what we need is some assumption that will do that for us so this assumption ensures that this signal here cache hit indicates whether there will be a hit or miss so if the cache is valid and the cache is ready the cache hit it will equal whatever the value of bit 13 is in the address and then what we can say is if we have a request valid and that bit is not set that means there's going to be a cache miss so we require that we have four to six cycles and then mem valid occurring because we've had a cache miss so the zero for bit 13 indicates a cache miss so we don't require that four to six cycles are mem valid if there is a cache hit of course because we won't be going out to external memory considerations when using data tagging and this tells you why it's not easily automated if at all it's attacks can only be applied to unused input bits so that's reserved fields for example ids and so on and it cannot be used as values in control path of the duty because obviously that will affect its behavior so basically that value must be able to propagate to the duty outputs unchanged and a formal environment must not restrict values on those bits and the reason for that is because that will deviate from what the design behavior would be so it's okay to have stability constraints because that allows all values to be seen and does without preventing values tagging only makes sense informal simulation will not respect any of those assumptions because in simulation assumptions mean nothing and in fact in the cadence simulator assumptions are converted to asserts which will cause a problem in any case you'll see that it's failing for no good reason so the recommendation then is don't use tagging for interface protocol properties only for end-to-end checks be careful to scrutinize what you're doing ie you're not over constraining when using tags because that is a common source of over constraints and it's not just one constraint itself it's the interaction of them so...