Built-In Func/Proc - Debugging with GDB
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##### 15.4.8.2 Built-in Functions and Procedures

Modula-2 also makes available several built-in procedures and functions. In describing these, the following metavariables are used:

a
  represents an `ARRAY` variable.
c
  represents a `CHAR` constant or variable.
i
  represents a variable or constant of integral type.
m
  represents an identifier that belongs to a set. Generally used in the same function with the metavariable s. The type of s should be `SET OF` mtype (where mtype is the type of m).
n
  represents a variable or constant of integral or floating-point type.
r
  represents a variable or constant of floating-point type.
t
  represents a type.
v
  represents a variable.
x
  represents a variable or constant of one of many types. See the explanation of the function for details.

All Modula-2 built-in procedures also return a result, described below.

`ABS(`n`)`
  Returns the absolute value of n.
`CAP(`c`)`
  If c is a lower case letter, it returns its upper case equivalent, otherwise it returns its argument.
`CHR(`i`)`
  Returns the character whose ordinal value is i.
`DEC(`v`)`
  Decrements the value in the variable v by one. Returns the new value.
`DEC(`v`,`i`)`
  Decrements the value in the variable v by i. Returns the new value.
`EXCL(`m`,`s`)`
  Removes the element m from the set s. Returns the new set.
`FLOAT(`i`)`
  Returns the floating point equivalent of the integer i.
`HIGH(`a`)`
  Returns the index of the last member of a.
`INC(`v`)`
  Increments the value in the variable v by one. Returns the new value.
`INC(`v`,`i`)`
  Increments the value in the variable v by i. Returns the new value.
`INCL(`m`,`s`)`
  Adds the element m to the set s if it is not already there. Returns the new set.
`MAX(`t`)`
  Returns the maximum value of the type t.
`MIN(`t`)`
  Returns the minimum value of the type t.
`ODD(`i`)`
  Returns boolean TRUE if i is an odd number.
`ORD(`x`)`
  Returns the ordinal value of its argument. For example, the ordinal value of a character is its ascii value (on machines supporting the ascii character set). x must be of an ordered type, which include integral, character and enumerated types.
`SIZE(`x`)`
  Returns the size of its argument. x can be a variable or a type.
`TRUNC(`r`)`
  Returns the integral part of r.
`TSIZE(`x`)`
  Returns the size of its argument. x can be a variable or a type.
`VAL(`t`,`i`)`
  Returns the member of the type t whose ordinal value is i.

> Warning: Sets and their operations are not yet supported, so gdb treats the use of procedures `INCL` and `EXCL` as an error.