gasp.info: Variables
Go forward to Macros
Go backward to Loops
Go up to Commands
Go to the top op gasp
Preprocessor variables
You can use variables in GASP to represent strings, registers, or
the results of expressions.
You must distinguish two kinds of variables:
1. Variables defined with `.EQU' or `.ASSIGN'. To evaluate this kind
of variable in your assembly output, simply mention its name. For
example, these two lines define and use a variable `eg':
eg .EQU FLIP-64
...
mov.l eg,r0
_Do not use_ this kind of variable in conditional expressions or
while loops; GASP only evaluates these variables when writing
assembly output.
2. Variables for use during preprocessing. You can define these with
`.ASSIGNC' or `.ASSIGNA'. To evaluate this kind of variable,
write `\&' before the variable name; for example,
opcit .ASSIGNA 47
...
.AWHILE \&opcit GT 0
...
.AENDW
GASP treats macro arguments almost the same way, but to evaluate
them you use the prefix `\' rather than `\&'. *Note Defining your
own directives: Macros.
`PVAR .EQU EXPR'
Assign preprocessor variable PVAR the value of the expression
EXPR. There are no restrictions on redefinition; use `.EQU' with
the same PVAR as often as you find it convenient.
`PVAR .ASSIGN EXPR'
Almost the same as `.EQU', save that you may not redefine PVAR
using `.ASSIGN' once it has a value.
`PVAR .ASSIGNA AEXPR'
Define a variable with a numeric value, for use during
preprocessing. AEXPR must be an absolute expression. You can
redefine variables with `.ASSIGNA' at any time.
`PVAR .ASSIGNC "STR"'
Define a variable with a string value, for use during
preprocessing. You can redefine variables with `.ASSIGNC' at any
time.
`PVAR .REG (REGISTER)'
Use `.REG' to define a variable that represents a register. In
particular, REGISTER is _not evaluated_ as an expression. You may
use `.REG' at will to redefine register variables.
All these directives accept the variable name in the "label"
position, that is at the left margin. You may specify a colon after
the variable name if you wish; the first example above could have
started `eg:' with the same effect.
Created Wed Sep 1 16:42:12 2004 on bee with info_to_html version 0.9.6.