Variables, Expressions, and Integrals

In a linker command file, all symbol names must start with the underscore character (_). The other characters can be letters, digits, or underscores. These valid lines for an LCF assign values to two symbols:

  _dec_num = 99999999;

  _hex_num_ = 0x9011276;

Use the standard assignment operator to create global symbols and assign their addresses, according to the pattern:

  _symbolicname = some_expression;

Note: There must be a semicolon at the end of a symbol assignment statement. A symbol assignment is valid only at the start of an expression, so a line such as this is not valid: _sym1 + _sym2 = _sym3;

When the system evaluates an expression and assigns it to a variable, the expression receives the type value absolute or a relocatable:

Absolute expression - the symbol contains the value that it will have in the output file.
Relocatable expression - the value expression is a fixed offset from the base of a section.

LCF syntax for expressions is very similar to the syntax of the C programming language:

All integer types are long or unsigned long.
Octal integers begin with a leading zero; other digits are 0 through 7, as these symbol assignments show:
```
_octal_number = 01374522;
```
```
_octal_number2 = 032405;
```
Decimal integers begin with any non-zero digit; other digits are 0 through 9, as these symbol assignments show:
```
_dec_num = 99999999;
```
```
_decimal_number = 123245;
```
```
_decvalfour = 9011276;
```
Hexadecimal integers begin with a zero and the letter x; other digits are 0 through f, as these symbol assignments show:
```
_hex_number = 0x999999FF;
```
```
_firstfactorspace = 0X123245EE;
```
```
_fifthhexval = 0xFFEE;
```
Negative integers begin with a minus sign:
```
_decimal_number = -123456;
```