Integer literals

The examples so far have illustrated the use of only standard integer literals such as 0, 10 and 255. However, like bit-string literals, numeric literals can be expressed in several forms. In a s)mfhesis environment the use of numeric literals is limited to the integer and based types. Examples of the forms that integer literals may take are as follows. 

The base integer specifies the base. The extended digits (0 to 9 and A to F) form the integer expression in that base and there is an optional exponent. The following examples illustrate based literals that are equivalent to the integer literal 128 ... 

Note that the exponent applies to the based literal not die equivalent integer literal. Also, depending on the base being used, only certain extended digits can be used. For example, base 2 can only use 0 or 1 in its expression. 

For larger masses, the possibilities increase enormously. At mass 100, there would be literally thousands of possible elemental compositions so that, although integer mass can be measured mass spectromet-rically, attempts to obtain elemental compositions will not lead to a definite answer. 

A direct way to calculate the time correlation function from the values saved during the simulation run is just to literally implement its definition. Suppose we have M+ values of. 4(0 and B t), obtained at the regular time intervals mSt, where m is an integer running from 1 to M, stored in the... 

As a result, the relation that permits us to calculate Q from Q and % is not always as simple as Eq. (7.1) since, quite evidently, the stoichiometric coefficients Va and Vb must intervene into it. A development of profound importance has been the introduction of the concept of an equivalent. The titrant or titrand equivalent is its mole number, integer or fractional, which must be dissolved to prepare one liter of solution for Eq. (7.1) to be obeyed. The number of equivalents in one solution liter is called its normality. The normality is hence another expression of the quantity of... 

All ofthe literally millions of different substances are composed of only around 100 elements. Each atom of a particular element is chemically identical to every other atom and contains the same number of protons in its nucleus. This number of protons in the nucleus of each atom of an element is the atomic number of the element. Atomic numbers are integers ranging from 1 to more than 100, each of which denotes a particular element. In addition to atomic numbers, each element has a name and a chemical symbol, such as carbon, C potassium, K (for its Latin name kalium) or cadmium, Cd. In addition to atomic number, name, and chemical symbol, each element has an atomic mass (atomic weight). The atomic mass of each element is the average mass of all atoms of the element, including the various isotopes of which it consists. The atomic mass unit, u (also called the dalton), is used to express masses of individual atoms and molecules (aggregates of atoms). These terms are summarized in Figure 1.2. 

A constant is a static object and so may be used in such a case. Also, integer and based literals (Chapter 6) and enumeration literals are static values. Signals and variables are dynamic objects. 

Others also exist but are not defined for use in synthesizeable descriptions- Note that when numerals are used as identifiers they must be written as 0 and not simply 0, as this is an integer value and not an enumerate literal. 

The arithmetic operators in VHDL can operate on any predefined numeric type. For a synthesizeable design their use is dierefore limited to integer types. Box 6.1 illustrates ways of expressing synthesizeable numeric literals. The operators can be subdivided into die following classes. 

E indicates an exponent. The exponent value must be a non-negative integer if the literal is to be an integer a negative value would produce a real literal, which cannot be synthesized. The underscore diar-acter can be used freely to aid the readability. 

Based literals allow an integer value to be expressed in any base from 2 to 16. They have the general form ... 

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