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.
