Synthesis full case

VHDL, by definition, requires that all the different values of an expression in a case statement be covered. However, this is not required in Verilog. If the user knows that all possible values of the case expression have been covered, one should use the Synopsys synthesis full case pragma. This prevents latches from being inferred due to not assigning values to a reg/signal under all possible conditions. 

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. 

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. 

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

A somewhat related process, the cobalt-mediated synthesis of symmetrical benzo-phenones from aryl iodides and dicobalt octacarbonyl, is shown in Scheme 6.49 [100]. Here, dicobalt octacarbonyl is used as a combined Ar-I bond activator and carbon monoxide source. Employing acetonitrile as solvent, a variety of aryl iodides with different steric and electronic properties underwent the carbonylative coupling in excellent yields. Remarkably, in several cases, microwave irradiation for just 6 s was sufficient to achieve full conversion An inert atmosphere, a base or other additives were all unnecessary. No conversion occurred in the absence of heating, regardless of the reaction time. However, equally high yields could be achieved by heating the reaction mixture in an oil bath for 2 min. 

The upscaling of nanocarbon production, while considering purity and homogeneity aspects in the kilogram scale, is a very important factor. Except for multi-walled CNTs no such process has been industrialized so far. If commercially available, high-purity nanocarbon materials provide exorbitant costs of up to several hundred Euro per milligram, which in most cases is inacceptable for applied research. As a consequence, nanocarbons are often synthesized in-house, which substantially lowers the comparability among different studies. Synthesis, characterization, and application must go hand-in-hand to exploit the full potential of nanocarbons. 

In this demonstration of a Fourier series we will use only cosine waves to reproduce the shadow image of the black squares. The procedure itself is rather straightforward, we just need to know the proper values for the amplitude A and the index h for each wave. The index h determines the frequency, i.e. the number of full waves trains per unit cell along the a-axis, and the amplitude determines the intensity of the areas with high (black) potential. As outlined in Figure 4, the Fourier synthesis for the present case is the sum of the following terms ... 

The presence of a certain number of amino acids is significant for the restitution of the immune system s cells, interferon synthesis process and other factors realization of the immune defense system. The decrease of full-form protein consumption is one of the causes of secondary immune-deficiency states. The significance of ascorbic acid presence for the immune system is supported by the fact that its concentration in the neutrophil granulocytes is 150 times higher than in the blood serum. The significance of retinol s and carotenoids role is supported in the cases of cell differentiation, where DNA synthesis increase, and proliferation decrease thus stabilizing the organism when under infection. 

The term diversity-oriented synthesis (DOS) is relatively new and, as mentioned above, is usually defined as the synthesis of complex, natural product-like molecules using a combinatorial approach and employing the full palette of modern organic reactions. It may be a subject of discussion what exactly qualifies a molecule as being natural product-like [4], and in most cases the similarity to an actual natural product seems reciprocal to the number of synthesized compounds. However, even in less complex cases, the products may be highly substituted polycyclic structures with defined stereochemistry, reminiscent of natural products [19, 20]. In these cases, a moderately complex backbone structure is subsequently modified with a well-established set of selective reactions to introduce diversity. 

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