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16 Immediate words

16.1. When the interpreter translates
The word introducing the colon word definitions : creates the name, code and chain fields of the new word, then so-called. translates the interpreter into a translation state. This means that the interpreter does not execute the terms of his or her influence, but searches for their code address and stores them in the HERE address (in the parser of the word that is being created).

Whether the words found in my influence are performed or translated by the interpreter depends on the value of the system variable USATE (USER variable). If the value of the STATE is not 0, the words of my influence are translated.

Accordingly, if STATE 0 is an execution, if not, translation state.
The value of the STATE (including) the definitions: and the finishing; word says.

16.2. When the interpreter does not translate
Let's look at a fairly common definition:


With the above and 14.1. section , the COUNT parter looks like this:

DUP field address
1+ code domain name
SWAP code field
C @ code field address
; S code field address

Now add the same definition to a comment:

: COUNT (ff-cim --- length length) DUP 1+ SWAP C @;

From the above, it will appear in the second COUNT parse of the (word code field name (since the word STATE is not 0, the system is in translation state.) Common sense, however, suggests that the results of the two definitions should be the same if they only differ in a single comment, the common sense is correct: not all words are translated in the translation state, but exceptions to the rule are instant (immediate, immediate) words.

Immediate words are not even translated when the interpreter is in translation; every time the interpreter finds them, they are executed immediately.

A (an instant word, we can write words immediately; we just have to add the word fresh after word definition


so make it straightforward:

: JELENT (---)
   CR LATEST ID. "defines started"

If JELENT is used in a colon word definition, the meaning is written during the definition, but the whole thing has no effect on the resulting new word. Here is the third definition that creates exactly the same parsing as the previous two:


The instantaneous or non-immediate word of a word is the second bit of the length field of the name field, so-called. precedence bit. IMMEDIATE simply sets the last bit of the last word defined to 1.

16.3. When we pay instead of the interpreter (Compile)
How Does . " Word when used definition? Taking the value to be printed by definition, so immediately it has to be (so you can text only to read the definition at compile time). Should , but to have a word that is actually translated into the parsing of the word that is being generated, otherwise there is no one who writes the text during the run time.

(. ")

"Compiling word" is the name of the immediate words that make the code field for another word (the "running word") and the data for the running word work (field parameters) in the parser.

In our case . " The word translator, the (. ') Running words, the text is kiíratandó edge of the field parameters.
If there is a definition in which the word "." Was used:


then its paramount:

The word "." Does make sure that the FORTH hanger on it goes to the device and that the title interpreter does not attempt to interpret the byte of the hanger as a code address to use it for its operation the virgin finds his / her own return address, which is exactly the title of the font that you want to point out: from here, type the text and then manipulate the virus to point the return address after the string.

: (. ")
   DUP 1+
   R> +> R

(the length and the title of the string in

the worm)
( add the total length to a) (return address)

If you want an instant word to translate another (running) word, then a


we have to use word. For example, "


cheating in the series ( ".) kódmezõcímét the paramzõbe.
The word translates the word COMPILE behind it, that places the kódmezõcímét at HERE.

A. " Checks for a translation state:

:. "
   34 (the" delimiter character code ")
       COMPILE (.)
       HERE C @ (the dictionary pointer is the string)
       1+ ALLOT (behind it)
   ELSE (no translation, execution)

16.4. Literals
Literals are the numbers that are given in the definition; these interpreters enter the parser. The running word handling the literals a


For example the

: .HAT 6. ;

literally the 6 is a literal. The parable of the word looks like this:

LIT code field address
. kódmezõcíme
; S code field address

LIT makes sure that when running .HAT, you get 6 on the stack and also that the address interpreter does not look at the 6 as the execution address.
The value to be used in the word definition may be the result of an operation; say, we want to use the number of minutes per day 60 * 24. This can be anticipated, but you do not see what this was and how it was calculated; the multiplication can be written in the definition text, but it is executed at each run, which is a waste of time. Instead, we can also make the translation state a


so we eliminate it, produce the desired value in the vermin and a


so we return to the translation state. The value on the bug will be translated into the parser by literal literal LITERAL:

: PERCEK [60 24 *] LITERAL. "one minute a day";

The word LITERAL is, of course, immediate. If used in the definition, the LIT running word translates, behind, the value in the box as the field parameter. If not used in a definition, LITERAL does not do anything.
The source of the last three words learned:





16.5. Postpone Instant Words (on [COMPILE])
How does 'word' work? It should be an instant word, as it searches for the word behind the word in the dictionary when translating. The title then (if used in 'definition') appears as literal in the parsing.
There is nothing in it that we can not write:

: '
   0 = 0? ERROR (if there is no such thing,
   flush) DROP (Parameter Address on the Vermont)

If someone compares the end of the program with the LITERAL source text, you see that they are completely identical. However, LITERAL can not be included in the 'text: LITERAL is immediate and we do not want it to be' under the definition. Instead, we want you to use all 'immediate' activities when you use it. This is made possible by


, which eliminates the immediate behavior of the word behind it for this one occasion. The word 'original' is FIG:

: '
   0 = 0? ERROR (if there is no word left)

Now let's get acquainted with the LITERAL double-word version of DLITERAL:

   STATE @ IF (translation status)
     SWAP (the bottom element must be placed on the stack first)

What was that about?
Summary of Chapter 16

The words learned:

STATEMENT ( --- title )
USER variable. If it is 0, the interpreter will execute it if not, then translate the words to be interpreted (execution and translation status).
The last word defined is immediate (sets the so-called precedent bit to 1). This means that the word is not translated even in translation; if you want to translate it, you should use the word [COMPILE].
[COMPILE]   For a single occasion it eliminates the immediate behavior of the word behind it. This way you can translate the words immediately.
COMPILE   Use it in immediate words. Translates the word behind it.
[   Turns the system into a translation state.
]   Enables the system to take effect.
LIT (--- n) A running word that makes the one-word field parameter behind it on the stack.
liter   (n ---) during
the translated word: (--- n) when
executing: (n --- n) In
translation state translates the value found in the vermont literal, ie: translates the running word LIT into a single word field parameter n et. Thus, at run time, n is on the stack. In execution state no effect.
DLITERAL   when translating: (d ---) during
the translated word: (d) when
executing: (d --- d) In
translation state translates the double word value found in the vermont literally, which is translated into the stack when the compiled word runs. In execution state no effect.
(. ")   A. " Translated Run Word Prints to the outboard for FORTH that is behind the parade.


16.1. Make a list of the immediate words of the dictionary!

The second bits of the length words of the immediate words 1. Thus, if this longitude bent is placed on the stack and the logical AND result of binary
0000 0000 0100 0000
ie hexadecimal 40, we get the corresponding flag:
: AZONNALIAK (pmmark --- flag)
   NFA C @

Using the word EZEK-A known in Chapter 14, it is easy to finish:


16.2. Write a KNYO (---) word, which if used in the definition, the word defined defines how the definition is in a quake. So if, for example, the


HOL-VAN is in operation, it says: "I was 12 months old"

   [BLK @ B / SCR /] LITERAL
   . "I was in a hurry";

16.3. Write a "" word that can be used in the same definition as the "" word, but the translated word begins before the text is written.

:. ""

16.4. Define such a; word to indicate the termination of the definition with text.

   LATEST ID. (the name of the last word defined)
   . "definicio vege"
   [COMPILE]; (normal finish)

16.5. What can be the source of [COMPILE]?


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