Standard Package

Definition:

The STANDARD package predefines a number of types, subtypes, and functions which are visible to all design units.

Description

The STANDARD package is a part of the Language Specification. It defines basic types, subtypes, and functions, together with operators available for each of the (sub)types defined. The operators are specified implicitly. Below is a complete list of declared types, together with their predefined operators.

Contents:

The STANDARD package declares following types:

· BOOLEAN (with predefined
operators "and", "or", "nand", "nor", "xor", "xnor", "not", "=", "/=", "<", "<=", ">", ">="),

· BIT (with predefined operators "and", "or", "nand", "nor", "xor", "xnor", "not", "=", "/=", "<", "<=", ">", ">="),

· CHARACTER (with predefined operators "=", "/=", "<", "<=", ">", ">="),

· SEVERITY_LEVEL (with predefined operators "=", "/=", "<", "<=", ">", ">="),

· INTEGER (with predefined operators "=", "/=", "<", "<=", ">", ">=", "+", "-", "abs", "*", "/", "mod", "rem", "**"),

· REAL (with predefined operators "=", "/=", "<", "<=", ">", ">=", "+", "-", "abs", "*", "/", "**"),

· TIME (with predefined operators "=", "/=", "<", "<=", ">", ">=", "+", "-", "abs", "*", "/"),

· STRING (with predefined operators "=", "/=", "<", "<=", ">", ">=", "&"),

· BIT_VECTOR (with predefined
operators "and", "or", "nand", "nor", "xor", "xnor", "not", "sll", "srl", "sla", "sra", "rol", "ror", "=", "/=", "<", "<=", ">", ">=", "&"),

· FILE_OPEN_KIND (with predefined operators "=", "/=", "<", "<=", ">", ">="),

· FILE_OPEN_STATUS (with predefined operators "=", "/=", "<", "<=", ">", ">="),

and three subtypes:

· DELAY_LENGTH (subtype of TIME),

· POSITIVE (subtype of INTEGER),

· NATURAL (subtype of INTEGER),

See Boolean, Bit, Character, Integer, Real, Physical Types, String, Bit_Vector and File for details on respective types.

Important Notes

· Use of the STANDARD package is implicitly assumed by every VHDL simulator and compiler and need not to be explicitly declared by the 'use' clause.

· The user may not modify the contents of the package.