Full case directive

Caution, use of the full case directive can potentially lead to a functional mismatch between the design model and the synthesized netlist see Chapter 5 for such examples. 

The full case directive tells the synthesis tool that all possible values that can possibly occur in CurrentState have been listed and the value of Next-State is a don t-care for all other cases, and therefore, the synthesis tool should not generate latches for NextState. However this may not be true in simulation. It could happen that CurrentState for some reason, gets a value of 2 b00. In such a case, the case statement simulates as if NextState value is saved, but in the synthesized netlist, the value of NextState may not be saved. 

Figure 2-35 With full case synthesis directive no latches.

As the synthesized netlist shows, no latches are inferred for NextToggle when the full case synthesis directive is used. 

It is necessary to specify the full case synthesis directive, otherwise latches are inferred for Address. Alternatively, an initial assignment to Address before the case statement can also be made to avoid latches no synthesis directive is then necessary. This is shown in the following always statement. 

In this case, no latches are inferred for Z and NextState since the full case synthesis directive states that no other case item values can occur. However, the preferred style for not inferring latches is to use the default branch. 

The problem with this approach is that since it is impractical to list all possible values an integer can take, to avoid latches either the default case branch must be specified or the full case synthesis directive must be used. Another problem with this approach is not good readability. 

The two synthesis directives we have seen so far, full case and parallel case, can potentially cause functional mismatches to occur between the design model and the synthesized netlist. The problem is that these directives are recognized only by a synthesis tool and not by a simulation tool. In either of the cases, if the designer is not careful in specifying the directive, mismatches can occur. 

Here is an example of a full case synthesis directive. 

Recommendation Use caution when using the synthesis directives full case and parallel case. Use only if really necessary. 

In most parts of the world, except India, safflower seed is handled in bulk. In Califomia this is accomplished in large aluminum-sided, bottom-dumping, open-top truck trailers of approximately 10-121 capacity each, two of which are hauled in tandem to a field by a truck tractor unit. The trailers are left by the field to be filled by the farmer, and the tractor unit returns and hauls the full trailers directly to the oil mill or export terminal (in some cases up to 250 km away) or to a closer grain elevator for intermediate storage. In other parts of the United States, safflower is delivered in many types of grain trucking equipment and much of it is delivered to small country elevators where it is stored, cleaned if necessary, and subsequently loaded onto trucks or railroad hopper cars (which can hold between 50 and 701 of safflower seed) for delivery to a buyer. 

Figure B2.5.13. Schematic representation of the four different mechanisms of multiphoton excitation (i) direct, (ii) Goeppert-Mayer (iii) quasi-resonant stepwise and (iv) incoherent stepwise. Full lines (right) represent the coupling path between the energy levels and broken arrows the photon energies with angular frequency to (Aco is the frequency width of the excitation light in the case of incoherent excitation), see also [111].

For all point, axial rotation, and full rotation group symmetries, this observation holds if the orbitals are equivalent, certain space-spin symmetry combinations will vanish due to antisymmetry if the orbitals are not equivalent, all space-spin symmetry combinations consistent with the content of the direct product analysis are possible. In either case, one must proceed through the construction of determinental wavefunctions as outlined above. 

By considering the flow as stopped but the turbine casing full of liquid, it is intuitively obvious that to rotate the wheel or impeller in either direction power will have to be put in. As the flow increases... 

Estrone (54, Chart 6) contains a full retron for the o-quinonemethide-Diels-Alder transform which can be directly applied to give 55. This situation, in which the Diels-Alder transform is used early in the retrosynthetic analysis, contrasts with the case of ibogamine (above), or, for example, gibberellic acid (section 6.4), and a Diels-Alder pathway is relatively easy to find and to evaluate. As indicated in Chart 6, retrosynthetic conversion of estrone to 55 produces an intermediate which is subject to further rapid simplification. This general synthetic approach has successfully been applied to estrone and various analogs. ... 

The HF level as usual overestimates the polarity, in this case leading to an incorrect direction of the dipole moment. The MP perturbation series oscillates, and it is clear that the MP4 result is far from converged. The CCSD(T) method apparently recovers the most important part of the electron correlation, as compared to the full CCSDT result. However, even with the aug-cc-pV5Z basis sets, there is still a discrepancy of 0.01 D relative to the experimental value. 

The direction of rotation depends on the direction of the current in the coil, and thus the instrument is only suitable for D.C. It is, however, possible to incorporate a full-wave rectifier arranged as shown in Figure 17.11 in order to allow the instrument to measure A.C. quantities. The quantity measured is the RMS value only if the waveform of the current is truly sinusoidal. In other cases, a considerable error may result. In principle, the scale is linear but, if required, it can be made non-linear by suitably shaping the poles of the permanent magnet. The instrument reading is affected by the performance of the rectifier, which is a non-linear device, and this results in the scale also being non-linear. The error when measuring D.C. quantities can be as low as 0.1 per cent of full-scale deflection and instruments are available for currents between microamperes and up to 600 A. 

The proof of protection is more difficult to establish in this case for two reasons. First, the object is to restore passivity to the rebar and not to render it virtually immune to corrosion. Second, it is difficult to measure the true electrode potential of rebars under these conditions. This is because the cathodic-protection current flowing through the concrete produces a voltage error in the measurements made (see below). For this reason it has been found convenient to use a potential decay technique to assess protection rather than a direct potential measurement. Thus a 100 mV decay of polarisation in 4 h once current has been interrupted has been adopted as the criterion for adequate protection. It will be seen that this proposal does not differ substantially from the decay criterion included in Table 10.3 and recommended by NACE for assessing the full protection of steel in other environments. Of course, in this case the cathodic polarisation is intended to inhibit pit growth and restore passivity, not to establish effective immunity. 

The critical current and primary passivation potential will not appear on an anodic polarisation curve when the steady-state potential already is higher than In such a case the potentiostat is unable to provide direct data for constructing the full polarisation curve. If that portion of the curve below the steady-state potential is desired, then the potential has to be held constant at several points in this range and corrosion currents calculated from corrosion rates as determined from solution analyses and/or weight losses. 

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