Barco SilverWriter 800, Руководство по обслуживанию на месте

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Field Service Manual December 2003
Page 25 of 276
The Laser Tool Language : LTL
LTL is a language used to debug the laser machines. LTL is a stack-oriented
programming language, the operators of LTL are called "words" and the variables the
words operate on are transferred via a stack mechanism. LTL-words can operate on
integer constants, integer variables and string constants.
LTL-words can be combined to form single line programs, or when the built-in editor
is used, complete programs can be written. LTL supports also in-line editing, and it
remembers several former command lines. These can be revoked by using the up and
down arrow keys, changing the line, if necessary, and pressing the ‘<>’ key. LTL
input strokes are always converted to upper case before the execution starts.
LTL does not allow the creation of new words, that is combining the existing words
into a new user-defined word.
An integer constant is represented by its string representation; this can also be in
exponential notation: 123400 or 1234e2. A string constant is any alphanumeric string
between quotes: "ON", "OFF", " ". A variable must be declared first with the VAR
statement: name VAR
The above statement declares an integer variable with the label name. A variable is
always set to zero at declaration time.
But let's take a look at the stack concept. When you invoke LTL you get the "LTL>"-
prompt on the screen. This means that LTL has cleared the stack and is ready to
accept commands from the keyboard. Command execution starts when the ‘<>’ key
is pressed.
The stack itself is a data array with an execution-dependent size. A number or
constant that is moved to the stack is always pushed on the Top Of Stack, variables
can only be removed from TOS. When you put two or more variables on the stack, the
number that is entered last is on the TOS position, the former on TOS-1, and so on.
Constants are pushed on the stack by simply typing the number, variables are pushed
on the stack by typing their label (variable name).
Example
"a" var 1 2 a <>
Creates a variable "a", initializes "a" to zero and pushes 1, 2, and the value of "a",
which is zero, on the stack. After this operation the stack looks like this:
TOS: 0
2
1
The number on the TOS can be removed from the stack by using the DROP word,
swapping the numbers on TOS and TOS-1 can be done by using the SWAP word.
Example
drop swap <>
Drops the 0 from the stack and swaps the 2 with the 1, the stack now looks like this:
TOS: 1
2