Subversion Repositories open8_urisc

----------------------------------------------
Open8_assembler Documentation - Index
----------------------------------------------

1..... Introduction
2..... Assembler Directives
3..... Assembler Syntax
 3.1.. Case Sensitivity
 3.2.. Comments
 3.3.. Labels
 3.4.. Number Types
 3.5.. Strings
 3.6.. Mnemonics
4..... Error Messages
5..... Bugs
6..... Temporary Files
7..... Compiling
 7.1.. Compiling Object Files
 7.2.. Compiling Library Files
8..... Linking
9..... Arithmetics
10.... Open8_as Flags
11.... Good things to know about Open8_as
12.... Legal Note


----------------------------------------------
1.... Introduction
----------------------------------------------

This assembler was originally based on the WLA Assembler. The original
WLA assembler can be found at

http://www.iki.fi/~vhelin/wla.html

Please don't bother Ville Helin if Open8_as does something wrong. No doubt I've
introduced a bug or two when I modified it for Open8 uRISC code.

Note that the original assembler was targetted for other architectures, and
intended for use by game designers, so some of the samples aren't proper
Open8 uRISC code.

----------------------------------------------
2.... Assembler Directives
----------------------------------------------

Here are the supported directives (with examples) in Open8_as:

      .ASC "HELLO WORLD!"
      .ASCTABLE
      .ASCIITABLE
      .ASM
      .BR
      .BREAKPOINT
      .BYT 100, $30, %1000, "HELLO WORLD!"
      .DB 100, $30, %1000, "HELLO WORLD!"
      .DBCOS 0.2, 10, 3.2, 120, 1.3
      .DBRND 20, 0, 10
      .DBSIN 0.2, 10, 3.2, 120, 1.3
      .DEFINE IF $FF0F
      .DEF IF $FF0F
      .DS 256, $10
      .DSB 256, $10
      .DSTRUCT waterdrop INSTANCEOF water DATA "tingle", 40, 120
      .DSW 128, 20
      .DW 16000, 10, 255
      .DWCOS 0.2, 10, 3.2, 1024, 1.3
      .DWRND 20, 0, 10
      .DWSIN 0.2, 10, 3.2, 1024, 1.3
      .ELSE
      .EMPTYFILL $C9
      .ENDASM
      .ENDB
      .ENDE
      .ENDIF
      .ENDM 
      .ENDME
      .ENDR
      .ENDRO
      .ENDS
      .ENDST
      .ENUM $C000 
      .EQU IF $FF0F
      .FAIL
      .FCLOSE FP_DATABIN
      .FOPEN "data.bin" FP_DATABIN
      .FREAD FP_DATABIN DATA
      .FSIZE FP_DATABIN SIZE
      .IF DEBUG == 2
      .IFDEF IF
      .IFDEFM \2
      .IFEQ DEBUG 2
      .IFEXISTS "main.s"
      .IFGR DEBUG 2
      .IFGREQ DEBUG 1
      .IFLE DEBUG 2
      .IFLEEQ DEBUG 1
      .IFNDEF IF
      .IFNDEFM \2
      .IFNEQ DEBUG 2
      .INCBIN "sorority.bin"
      .INCDIR "/usr/programming/gb/include/"
      .INCLUDE "cgb_hardware.i"
      .INPUT NAME
      .MACRO TEST
      .ORG $150
      .OUTNAME "other.o"
      .PRINTT "Here we are...\n"
      .PRINTV DEC DEBUG+1
      .REDEFINE IF $F
      .REDEF IF $F
      .REPEAT 6
      .REPT 6
      .SEED 123
      .SECTION "Init" FORCE
      .SHIFT
      .STRUCT enemy_object
      .SYM SAUSAGE
      .SYMBOL SAUSAGE
      .UNDEFINE DEBUG
      .UNDEF DEBUG
      .WORD 16000, 10, 255


Descriptions:

----
.ASM
----

Tells Open8_as to start assembling. Use .ASM to continue the work which has been
disabled with .ENDASM. .ASM and .ENDASM can be used to mask away big blocks
of code. This is analogous to the ANSI C -comments (/*...*/), but .ASM and
.ENDASM can be nested, unlike the ANSI C -counterpart.

This is not a compulsory directive.

-------
.ENDASM
-------

Tells Open8_as to stop assembling. Use .ASM to continue the work.

This is not a compulsory directive.

----------------
.DBRND 20, 0, 10
----------------

Defines bytes, just like .DSB does, only this time they are filled with
(pseudo) random numbers. We use stdlib's rand() to generate the random
numbers. If you want to seed the random number generator, use .SEED.

The first parameter (20 in the example) defines the amount of numbers
we want to generate. The next two tell the range of the random numbers,
i.e. min and max.

Here's how it works:

.DBRND A, B, C

for (i = 0; i < A; i++)
  output_data((rand() % (C-B+1)) + B);

This is not a compulsory directive.

----------------
.DWRND 20, 0, 10
----------------

Analogous to .DBRND (but defines words).

This is not a compulsory directive.

-----------------------------
.DBCOS 0.2, 10, 3.2, 120, 1.3
-----------------------------

Defines bytes just like .DSB does, only this time they are filled with
cosine data. .DBCOS takes five arguments.

The first argument is the starting angle. Angle value ranges from 0 to
359.999..., but you can supply Open8_as with values that are out of the range -
Open8_as fixes them ok. The value can be integer or float.

The second one descibes the amount of additional angles. The example
will define 11 angles.

The third one is the adder value which is added to the angle value when
next angle is calculated. The value can be integer or float.

The fourth and fifth ones can be seen from the pseudo code below, which
also describes how .DBCOS works. The values can be integer or float.

Remember that cos (and sin) here returns values ranging from -1 to 1.

.DBCOS A, B, C, D, E

for (B++; B > 0; B--) {
  output_data((D * cos(A)) + E)
  A = keep_in_range(A + C)
}

This is not a compulsory directive.

-----------------------------
.DBSIN 0.2, 10, 3.2, 120, 1.3
-----------------------------

Analogous to .DBCOS, but does sin() instead of cos().

This is not a compulsory directive.

------------------------------
.DWCOS 0.2, 10, 3.2, 1024, 1.3
------------------------------

Analogous to .DBCOS (but defines words).

This is not a compulsory directive.

------------------------------
.DWSIN 0.2, 10, 3.2, 1024, 1.3
------------------------------

Analogous to .DBCOS (but defines words and does sin() instead of cos()).

This is not a compulsory directive.

--------------
.EMPTYFILL $C9
--------------

This byte is used in filling the unused areas of memory. EMPTYFILL
defaults to $00.

This is not a compulsory directive.

--------------------------------------
.INCDIR "/usr/programming/Open8/include/"    
--------------------------------------

Changes the current include root directory. Use this to specify main
directory for the following .INCLUDE and .INCBIN directives.
If you want to change to the current working directory (Open8_as also defaults
to this), use

.INCDIR ""

This is not a compulsory directive.

-------------------------
.INCLUDE "cgb_hardware.i"
-------------------------

Includes the specified file to the source file. If the file's not found
in the .INCDIR directory, Open8_as tries to find it in the current working
directory.

This is not a compulsory directive.

----------------------
.INCBIN "sorority.bin"
----------------------

Includes the specified data file into the source file. .INCBIN caches
all files into memory, so you can .INCBIN any data file millions of
times, but it is loaded from hard drive only once.

You can optionally use SWAP after the file name, e.g.,

.INCBIN "kitten.bin" SWAP

.INCBIN data is divided into blocks of two bytes, and inside every block
the bytes are exchanged (like "SWAP r" does to nibbles). This requires that
the size of the file is even.

You can also force Open8_as to skip n bytes from the beginning of the file
by writing for example:

.INCBIN "kitten.bin" SKIP 4

Four bytes are skipped from the beginning of kitten.bin and the rest
is incbinned.

It is also possible to incbin only n bytes from a file:

.INCBIN "kitten.bin" READ 10

Will read ten bytes from the beginning of kitten.bin.

You can also force Open8_as to create a definition holding the size
of the file:

.INCBIN "kitten.bin" FSIZE size_of_kitten

And you can combine all these four commands:

.INCBIN "kitten.bin" SKIP 10 READ 8 SWAP FSIZE size_of_kitten

This example shows how to incbin eight bytes (swapped) after skipping
10 bytes from the beginning of file "kitten.bin", and how to get the
size of the file into a definition label "size_of_kitten". Note that the
order of the extra commands is important.

If the file's not found in the .INCDIR directory, Open8_as tries to find it
in the current working directory.

This is not a compulsory directive.

-----------
.INPUT NAME
-----------

.INPUT is much like any Basic-language input: .INPUT asks the user
for a value or string. After .INPUT is the variable name used to store
the data.

.INPUT works like .REDEFINE, but the user gets to type in the data.

Here are few examples how to use input:

.PRINTT "The name of the TFT pic? "
.INPUT NAME
.NAME NAME

...

.PRINTT "Give the .DB amount.\n"
.INPUT S
.PRINTT "Give .DB data one at a time.\n"
.REPEAT S
  .INPUT B
  .DB B
.ENDR

...

This is not a compulsory directive.

-----
.FAIL
-----

Terminates the compiling process.

This is not a compulsory directive.

------------------
.FCLOSE FP_DATABIN
------------------

Closes the filehandle FP_DATABIN.

This is not a compulsory directive.

----------------------------
.FOPEN "data.bin" FP_DATABIN
----------------------------

Opens the file "data.bin" for reading and associates the filehandle with
name "FP_DATABIN".

This is not a compulsory directive.

----------------------
.FREAD FP_DATABIN DATA
----------------------

Reads one byte from "FP_DATABIN" and creates a definition called "DATA"
to hold it. "DATA" is an ordinary definition label, so you can .UNDEFINE it.

Here's an example on how to use .FREAD:

.fopen "data.bin" fp
.fsize fp t
.repeat t
.fread fp d
.db d+26
.endr
.undefine t, d

This is not a compulsory directive.

----------------------
.FSIZE FP_DATABIN SIZE
----------------------

Creates a definition called "SIZE", which holds the size of the file
associated with the filehandle "FP_DATABIN". "SIZE" is an ordinary
definition label, so you can .UNDEFINE it.

This is not a compulsory directive.

-----------
.MACRO TEST
-----------

Begins a macro called 'TEST'.

You can use '\@' inside a macro to e.g., separate a label from the other
macro 'TEST' occurrences. '\@' is replaced with an integer number
indicating the amount of times the macro has been called previously so
it is unique to every macro call. '\@' can also be used inside strings
inside a macro or just as a plain value. Look at the following examples
for more information.

Also, if you want to use macro arguments in e.g., calculation, you can
type '\X' where X is the number of the argument. Another way to refer
to the arguments is to use their names given in the definition of the
macro (see the examples for this).

Remember to use .ENDM to finish the macro definition. Note that you
cannot use .INCLUDE inside a macro. Note that Open8_as' macros are in fact
more like procedures than real macros, because Open8_as doesn't substitute
macro calls with macro data. Instead Open8_as jumps to the macro when it
encounters a macro call at compile time.

You can call macros from inside a macro. Note that the preprocessor
does not expand the macros. Open8_as traverses through the code according to
the macro calls, so macros really define a very simple programming
language.

Here are some examples:

.MACRO NOPMONSTER
       .REPT 32         ; it's just an example...
       NOP
       .ENDR
.ENDM

.MACRO LOAD_ABCD
       LD A, \1
       LD B, \2
       LD C, \3
       LD D, \4
       NOPMONSTER
       LD HL, 1<<\1
.INCBIN \5
.ENDM

.MACRO QUEEN

QUEEN\@:
        LD   A, \1
        LD   B, \1
        CALL QUEEN\@

        .DB  "\@", 0     ; will translate into a zero terminated string
                         ; holding the amount of macro QUEEN calls.
        .DB  "\\@", 0    ; will translate into a string containing
                         ; \@.
        .DB  \@          ; will translate into a number indicating
                         ; the amount of macro QUEEN calls.

.ENDM

.MACRO LOAD_ABCD_2 ARGS ONE, TWO, THREE, FOUR, FIVE
       LD A, ONE
       LD B, TWO
       LD C, THREE
       LD D, FOUR
       NOPMONSTER
       LD HL, 1< \2, etc.).
.SHIFT can thus only be used inside a .MACRO.

This is not a compulsory directive.

---------
.ORG $150
---------

Defines the starting address. The default starting address is $0

This is not a compulsory directive.

------------
.DS 256, $10
------------

.DS is an alias for .DSB.

This is not a compulsory directive.

-------------
.DSB 256, $10
-------------

Defines 256 bytes of $10.

This is not a compulsory directive.

----------------------------------------------------------
.DSTRUCT waterdrop INSTANCEOF water DATA "tingle", 40, 120
----------------------------------------------------------

Defines an instance of struct water, called waterdrop, and fills
it with the given data. Before calling .DSTRUCT we must have defined
the structure, and in this example it could be like:

.STRUCT water
name   ds 8
age    db
weight dw
.ENDST

Note that the keywords INSTANCEOF and DATA are optional, so

.DSTRUCT waterdrop, water, "tingle", 40, 120

also works. Also note that Open8_as fills the missing bytes with the data
defined with .EMPTYFILL, or $00 if no .EMPTYFILL has been issued.

In this example you would also get the following labels:

waterdrop
waterdrop.name
waterdrop.age
waterdrop.weight

This is not a compulsory directive.

------------
.DSW 128, 20
------------

Defines 128 words (two bytes) of 20.

This is not a compulsory directive.

-----------------------------------
.DB 100, $30, %1000, "HELLO WORLD!"
-----------------------------------

Defines bytes.

This is not a compulsory directive.

------------------------------------
.BYT 100, $30, %1000, "HELLO WORLD!"
------------------------------------

.BYT is an alias for .DB.

This is not a compulsory directive.

------------
.SYM SAUSAGE
------------

Open8_as treats symbols ("SAUSAGE" in this example) like labels, but they
only appear in the symbol files Open8_link outputs. Useful for finding out
the location where Open8_link puts data.

This is not a compulsory directive.

---------------
.SYMBOL SAUSAGE
---------------

.SYMBOL is an alias for .SYM.

This is not a compulsory directive.

---
.BR
---

Inserts a breakpoint that behaves like a .SYM without a name. Breakpoints
can only be seen in Open8_link's symbol file.

This is not a compulsory directive.

-----------
.BREAKPOINT
-----------

.BREAKPOINT is an alias for .BR.

This is not a compulsory directive.

-----------
.ASCIITABLE
-----------

.ASCIITABLE's only purpose is to provide character mapping for .ASC.
Take a look at the example:

.ASCIITABLE
MAP "A" TO "Z" = 0
MAP "!" = 90
.ENDA

Here we set such a mapping that character 'A' is equal to 0, 'B'
is equal to 1, 'C' is equal to 2, and so on, and '!' is equal to 90.

After you've given the .ASCIITABLE, use .ASC to define bytes using
this mapping (.ASC is an alias for .DB, but with .ASCIITABLE mapping).
For example, .ASC "AB!" would define bytes 0, 1 and 90.

Note that the following works as well:

.ASCIITABLE
MAP 'A' TO 'Z' = 0
MAP 65 = 90
.ENDA

Also note that the characters that are not given any mapping in
.ASCIITABLE map to themselves (i.e., 'A' maps to 'A', etc.).

This is not a compulsory directive.

---------
.ASCTABLE
---------

.ASCTABLE is an alias for .ASCIITABLE.

This is not a compulsory directive.

-------------------
.ASC "HELLO WORLD!"
-------------------

.ASC is an alias for .DB, but if you use .ASC it will remap
the characters using the mapping given via .ASCIITABLE.

This is not a compulsory directive.

------------------
.DW 16000, 10, 255
------------------

Defines words (two bytes each). .DW takes only numbers and
characters as input, not strings.

This is not a compulsory directive.

--------------------
.WORD 16000, 10, 255
--------------------

.WORD is an alias for .DW.

This is not a compulsory directive.

----------------
.DEFINE IF $FF0F
----------------

Assigns a number or a string to a definition label.

By default all defines are local to the file where they are
presented. If you want to make the definition visible to all the
files in the project, use .EXPORT.

Here are some examples:

.DEFINE X 1000
.DEFINE FILE "PD-03.TFT"
.DEFINE TXT1 "hello and welcome", 1, "to the Open8", 0
.DEFINE BYTES 1, 2, 3, 4, 5
.DEFINE COMPUTATION X+1
.DEFINE DEFAULTV

All definitions with multiple values are marked as data strings,
and .DB is about the only place where you can later on use them.

.DEFINE BYTES 1, 2, 3, 4, 5
.DB 0, BYTES, 6

is the same as

.DB 0, 1, 2, 3, 4, 5, 6

If you omit the definition value (in our example "DEFAULTV"), Open8_as
will default to 0.

Note that you must do your definition before you use it, otherwise
Open8_as will use the final value of the definition. Here's an example
of this:

.DEFINE AAA 10
.DB AAA            ; will be 10.
.REDEFINE AAA 11

but

.DB AAA            ; will be 11.
.DEFINE AAA 10
.REDEFINE AAA 11

You can also create definitions on the command line. Here's an
example of this:

Open8_as AS -vl -DMOON -DNAME=john -DPRICE=100 -DADDRESS=$100 math.s

MOON's value will be 0, NAME is a string definition with value "john",
PRICE's value will be 100, and ADDRESS's value will be $100.

Note that

.DEFINE AAA = 10   ; the same as ".DEFINE AAA 10".

works as well.

This is not a compulsory directive.

-------------
.DEF IF $FF0F
-------------

.DEF is an alias for .DEFINE.

This is not a compulsory directive.

-------------
.EQU IF $FF0F
-------------

.EQU is an alias for .DEFINE.

This is not a compulsory directive.

----------------
.REDEFINE IF $0F
----------------

Assigns a new value or a string to an old definition. If the
definition doesn't exist, .REDEFINE performs .DEFINE's work.

When used with .REPT REDEFINE helps creating tables:

.DEFINE CNT 0

.REPT 256
.DB CNT
.REDEFINE CNT CNT+1
.ENDR

This is not a compulsory directive.

-------------
.REDEF IF $0F
-------------

.REDEF is an alias for .REDEFINE.

This is not a compulsory directive.

--------------
.IF DEBUG == 2
--------------

If the condition is fulfilled the following piece of code is
acknowledged until .ENDIF/.ELSE occurs in the text, otherwise
it is skipped. Operands must be immediate values or strings.

The following operators are supported:
<  - less than
<= - less or equal to
>  - greater than
>= - greater or equal to
== - equals to
!= - doesn't equal to

All IF (yes, including .IFDEF, .IFNDEF, etc) directives can be
nested.

This is not a compulsory directive.

---------
.IFDEF IF
---------

If "IF" is defined, then the following piece of code is acknowledged
until .ENDIF/.ELSE occurs in the text, otherwise it is skipped.

This is not a compulsory directive.

------------------
.IFEXISTS "main.s"
------------------

If "main.s" file can be found, then the following piece of code is
acknowledged until .ENDIF/.LESE occurs in the text, otherwise it is
skipped.

By writing the following few lines you can include a file if it exists
without breaking the compiling loop if it doesn't exist.

.IFEXISTS FILE
.INCLUDE FILE
.ENDIF

This is not a compulsory directive.

---------------
.UNDEFINE DEBUG
---------------

Removes the supplied definition label from system. If there is no
such label as given no error is displayed as the result would be the
same.

You can undefine as many definitions as you wish with one .UNDEFINE:

.UNDEFINE NUMBER, NAME, ADDRESS, COUNTRY
.UNDEFINE NAME, AGE

This is not a compulsory directive.

------------
.UNDEF DEBUG
------------

.UNDEF is an alias for .UNDEFINE.

This is not a compulsory directive.

----------
.IFNDEF IF
----------

If "IF" is not defined, then the following piece of code is acknowledged
until .ENDIF/.ELSE occurs in the text, otherwise it is skipped.

This is not a compulsory directive.

----------
.IFDEFM \2
----------

If the specified argument is defined (argument number two, in the example),
then the following piece of code is acknowledged until .ENDIF/.ELSE occurs
in the macro, otherwise it is skipped.

This is not a compulsory directive. .IFDEFM works only inside a macro.

-----------
.IFNDEFM \2
-----------

If the specified argument is not defined, then the following piece of
code is acknowledged until .ENDIF/.ELSE occurs in the macro, otherwise
it is skipped.

This is not a compulsory directive. .IFNDEFM works only inside a macro.

-------------
.IFEQ DEBUG 2
-------------

If the value of DEBUG equals to 2, then the following piece of code is
acknowledged until .ENDIF/.ELSE occurs in the text, otherwise it is skipped.
Both arguments can be computations, defines or immediate values.

This is not a compulsory directive.

--------------
.IFNEQ DEBUG 2
--------------

If the value of DEBUG doesn't equal to 2, then the following piece of
code is acknowledged until .ENDIF/.ELSE occurs in the text, otherwise it is
skipped. Both arguments can be computations, defines or immediate
values.

This is not a compulsory directive.

-------------
.IFLE DEBUG 2
-------------

If the value of DEBUG is less than 2, then the following piece of code is
acknowledged until .ENDIF/.ELSE occurs in the text, otherwise it is skipped.
Both arguments can be computations, defines or immediate values.

This is not a compulsory directive.

---------------
.IFLEEQ DEBUG 2
---------------

If the value of DEBUG is less or equal to 2, then the following piece of code is
acknowledged until .ENDIF/.ELSE occurs in the text, otherwise it is skipped.
Both arguments can be computations, defines or immediate values.

This is not a compulsory directive.

-------------
.IFGR DEBUG 2
-------------

If the value of DEBUG is greater than 2, then the following piece of code is
acknowledged until .ENDIF/.ELSE occurs in the text, otherwise it is skipped.
Both arguments can be computations, defines or immediate values.

This is not a compulsory directive.

---------------
.IFGREQ DEBUG 2
---------------

If the value of DEBUG is greater or equal to 2, then the following piece of code is
acknowledged until .ENDIF/.ELSE occurs in the text, otherwise it is skipped.
Both arguments can be computations, defines or immediate values.

This is not a compulsory directive.

-----
.ELSE
-----

If the previous .IFxxx failed then the following text until
.ENDIF is acknowledged.

This is not a compulsory directive.

------
.ENDIF
------

This terminates any .IFxxx directive.

This is not a compulsory directive, but if you use any .IFxxx then
you need also to apply this.

---------
.REPEAT 6
---------

Repeats the text enclosed between ".REPEAT x" and ".ENDR" x times (6 in
this example). You can use .REPEATs inside .REPEATs. 'x' must be >= 0.

This is not a compulsory directive.

-------
.REPT 6
-------

.REPT is an alias for .REPEAT.

This is not a compulsory directive.

-----
.ENDR
-----

Ends the repetition.

This is not a compulsory directive, but when .REPEAT is used this one is
required to terminate it.

-----------
.ENUM $C000
-----------

Starts enumeration from $C000. Very useful for defining variables.

To start a descending enumeration, put "DESC" after the starting
address. Open8_as defaults to "ASC" (ascending enumeration).

You can also add "EXPORT" after these if you want to export all
the generated definitions automatically.

Here's an example of .ENUM:

...
.STRUCT mon                ; check out the documentation on
name ds 2                  ; .STRUCT
age  db
.ENDST

.ENUM $A000
_scroll_x DB               ; db  - define byte (byt and byte work also)
_scroll_y DB
player_x: DW               ; dw  - define word (word works also)
player_y: DW
map_01:   DS  16           ; ds  - define size (bytes)
map_02    DSB 16           ; dsb - define size (bytes)
map_03    DSW  8           ; dsw - define size (words)
monster   INSTANCEOF mon 3 ; three instances of structure mon
dragon    INSTANCEOF mon   ; one mon
.ENDE
...

Previous example transforms into following definitions:

.DEFINE _scroll_x      $A000
.DEFINE _scroll_y      $A001
.DEFINE player_x       $A002
.DEFINE player_y       $A004
.DEFINE map_01         $A006
.DEFINE map_02         $A016
.DEFINE map_03         $A026
.DEFINE monster        $A036
.DEFINE monster.name   $A036
.DEFINE monster.age    $A038
.DEFINE monster.1      $A036
.DEFINE monster.1.name $A036
.DEFINE monster.1.age  $A038
.DEFINE monster.2      $A039
.DEFINE monster.2.name $A039
.DEFINE monster.2.age  $A03B
.DEFINE monster.3      $A03C
.DEFINE monster.3.name $A03C
.DEFINE monster.3.age  $A03E
.DEFINE dragon         $A03F
.DEFINE dragon.name    $A03F
.DEFINE dragon.age     $A041

DB, DW, DS, DSB, DSW and INSTANCEOF can also be in lowercase. You
can also use a dotted version of the symbols, but it doesn't advance
the memory address. Here's an exmple:

.ENUM $C000 DESC EXPORT
bigapple_h db
bigapple_l db
bigapple:  .dw
.ENDE

And this is what is generated:

.DEFINE bigapple_h $BFFF
.DEFINE bigapple_l $BFFE
.DEFINE bigapple   $BFFE
.EXPORT bigapple, bigapple_l, bigapple_h

This way you can generate a 16bit variable address along with pointers
to its parts.

If you want more flexible variable positioning, take a look at
.RAMSECTIONs.

This is not a compulsory directive.

-----
.ENDE
-----

Ends the enumeration.

This is not a compulsory directive, but when .ENUM is used this one is
required to terminate it.

--------------------
.STRUCT enemy_object
--------------------

Begins the definition of a structure. These structures can be placed
inside RAMSECTIONs and ENUMs. Here's an example:

.STRUCT enemy_object
id    dw               ; the insides of a .STRUCT are 1:1 like in .ENUM
x     db               ; except that no structs inside structs are
y     db               ; allowed.
data  ds  10
info  dsb 16
stats dsw  4
.ENDST

This also creates a definition "_sizeof_[struct name]", in our example
this would be "_sizeof_enemy_object", and the value of this definition
is the size of the object, in bytes (2+1+1+10+16+4*2 = 38 in the example).

You'll get the following definitions as well:

enemy_object.id    (== 0)
enemy_object.x     (== 2)
enemy_object.y     (== 3)
enemy_object.data  (== 4)
enemy_object.info  (== 14)
enemy_object.stats (== 30)

After defining a .STRUCT you can create an instance of it in a .RAMSECTION /
.ENUM by typing

 INSTANCEOF  [optional, the number of structures]

Here's an example:

.RAMSECTION "enemies" BANK 4 SLOT 4
enemies   INSTANCEOF enemy_object 4
enemyman  INSTANCEOF enemy_object
enemyboss INSTANCEOF enemy_object
.ENDS

This will create labels like "enemies", "enemies.id", "enemies.x", "enemies.y"
and so on. Label "enemies" is followed by four "enemy_object" structures,
and only the first one is labeled. After there four come "enemyman" and
"enemyboss" instances.

Take a look at the documentation on .RAMSECTION & .ENUM, they have more
examples of how you can use .STRUCTs.

A WORD OF WARNING: Don't use labels b, B, w and W inside a struct as e.g.,
Open8_as sees enemy.b as a byte sized reference to enemy. All other labels should
be safe.

lda enemy1.b  ; load a byte from zeropage address enemy1 or from the address
              ; of enemy1.b??? i can't tell you, and Open8_as can't tell you...

This is not a compulsory directive.

------
.ENDST
------

Ends the structure definition.

This is not a compulsory directive, but when .STRUCT is used this one is
required to terminate it.

---------
.SEED 123
---------

Seeds the random number generator.

This is not a compulsory directive. The random number generator is
initially seeded with the output of time(), which is, according to
the manual, "the time since the Epoch (00:00:00 UTC, January 1, 1970),
measured in seconds". So if you don't .SEED the random number generator
yourself with a constant value, .DBRND and .DWRND give you different
values every time you run Open8_as.

---------------------
.SECTION "Init" FORCE
---------------------

Section is a continuous area of data which is placed into the output
file according to the section type and .ORG directive
values.

The example begins a section called "Init". Before a section can be
declared, .ORG must be used unless Open8_as is in library file
output mode. Library file's sections must all be FREE ones. .BANK tells
the bank number where this section will be later relocated into. .ORG
tells the offset for the relocation from the beginning of .BANK.

You can supply the preferred section size (bytes) inside the section
name string. Here's an example:

.SECTION "Init_100" FREE

will create a section ("Init") with size of 100 bytes, unless the actual
data overflows from the section, in which case the section size is
enlarged to contain all the data. Note that the syntax for explicit
section size defining is: "NAME_X", where "NAME" is the name of the
section and "X" is the size (decimal or hexadecimal value). 

You can also give the size of the section the following way:

.SECTION "Init" SIZE 100 FREE

It's possible to force Open8_link to align the FREE, SEMIFREE and SUPERFREE
sections by giving the alignment as follows:

.SECTION "Init" SIZE 100 ALIGN 4 FREE

And if you want that Open8_as returns the ORG to what it was before issuing
the section, put RETURNORG at the end of the parameter list:

.SECTION "Init" SIZE 100 ALIGN 4 FREE RETURNORG

By default Open8_as advances the ORG, so, for example, if your ORG was $0 before
a section of 16 bytes, then the ORG will be 16 after the section.

Note also that if your section name begins with double underlines (e.g.,
"__UNIQUE_SECTION!!!") the section will be unique in the sense that
when Open8_link recieves files containing sections which share the same
name, Open8_link will save only the first of them for further processing,
all others are deleted from memory with corresponding labels, references
and calculations.

If a section name begins with an exclamation mark ('!') it tells
Open8_link to not to drop it, even if you use Open8_link's ability to discard
all unreferenced sections and there are no references to the section.

FORCE after the name of the section tells Open8_as that the section _must_ be
inserted so it starts at .ORG. FORCE can be replaced with FREE which
means that the section can be inserted somewhere in the defined bank,
where there is room. You can also use OVERWRITE to insert the section
into the memory regardless of data collisions. Using OVERWRITE you can
easily patch an existing ROM image just by .BACKGROUND'ing the ROM image and
inserting OVERWRITE sections into it. SEMIFREE sections are also
possible and they behave much like FREE sections. The only difference
is that they are positioned somewhere in the bank starting from .ORG.
SUPERFREE sections are also available, and they will be positioned into
the first suitable place inside the first suitable bank (candidates
for these suitable banks have the same size with the slot of the section,
no other banks are considered). You can also leave away the type
specifier as the default type for the section is FREE.

You can name the sections as you wish, but there is one special name.
A section called "BANKHEADER" is placed in the front of the bank
where it is defined. These sections contain data that is not in the
memory map of the machine, so you can't refer to the data of a
BANKHEADER section, but you can write references to outside. So no
labels inside BANKHEADER sections. These special sections are useful
when writing e.g., MSX programs. Note that library files don't take
BANKHEADER sections.

Here's an example of a "BANKHEADER" section:

.BANK 0
.ORG 0
.SECTION "BANKHEADER"
        .DW MAIN
        .DW VBI
.ENDS

.SECTION "Program"
MAIN:    CALL   MONTY_ON_THE_RUN
VBI:     PUSH   HL
         ...
         POP    HL
         RETI
.ENDS

Here's an example of an ordinary section:

.BANK 0
.ORG $150
.SECTION "Init" FREE
        DI
        LD  SP, $FFFE
        SUB A
        LD  ($FF00+R_IE), A
.ENDS

This tells Open8_as that a FREE section called "Init" must be located somewhere
in bank 0. If you replace FREE with SEMIFREE the section will be inserted
somewhere in the bank 0, but not in the $0-$14F area. If you replace FREE
with SUPERFREE the section will be inserted somewhere in the 

Here's the order in which Open8_as writes the sections:
1. FORCE
2. SEMIFREE & FREE
3. SUPERFREE
4. OVERWRITE

Before the sections are inserted into the output file, they are sorted by
size, so that the biggest section gets processed first and the smallest
last.

You can also create a RAM section. For more information about them, please
read the .RAMSECTION directive explanation.

This is not a compulsory directive.

--------------
.EXPORT work_x
--------------

Exports the definition "work_x" to outside world. Exported definitions are
visible to all object files and libraries in the linking procedure. Note
that you can only export value definitions, not string definitions.

You can export as many definitions as you wish with one .EXPORT:

.EXPORT NUMBER, NAME, ADDRESS, COUNTRY
.EXPORT NAME, AGE

This is not a compulsory directive.

--------------------------
.PRINTT "Here we are...\n"
--------------------------

Prints the given text into stdout. Good for debugging stuff. PRINTT takes
only a string as argument, and the only supported formatting symbol is '\n'
(line feed).

This is not a compulsory directive.

-------------------
.PRINTV DEC DEBUG+1
-------------------

Prints the value of the supplied definition or computation into stdout.
Computation must be solvable at the time of printing (just like definitions
values). PRINTV takes two parameters. The first describes the type of the
print output. "DEC" means decimal, "HEX" means hexadecimal.

Use PRINTV with PRINTT as PRINTV doesn't print linefeeds, only the result.
Here's an example:

.PRINTT "Value of \"DEBUG\" = $"
.PRINTV HEX DEBUG
.PRINTT "\n"

This is not a compulsory directive.

------------------
.OUTNAME "other.o"
------------------

Changes the name of the output file. Here's and example:

Open8_as -o test.s

would normally output "test.o", but if you had written

.OUTNAME "new.o"

somewhere in the code Open8_as would write the output to new.o instead.

This is not a compulsory directive.


----------------------------------------------
3.... Assembler Syntax
----------------------------------------------


3.1. Case Sensitivity

Open8_as is case sensitive, so be careful.


3.2. Comments

Comments begin with ';' or '*' and end along with the line. ';' can be
used anywhere, but '*' can be placed only at the beginning of a new line.

Open8_as also has ANSI-C -like commenting. This means you can start a 
multiline comment with "/*" and end it with "*/". Additionally, it has
.ASM and .ENDASM directives. These function much like ANSI-C comments, but 
unlike the ANSI-C comments these can be nested.


3.3. Labels

Labels are ordinary strings (which can also end to a ':'). Labels starting
with "_" are considered to be local labels and do not show outside sections
where they were defined, or outside object files, if they were not defined
inside a section.

Here are few examples of different labels:

VBI_IRQ:
VBI_IRQ2
_VBI_LOOP:
main:

3.4. Number Types

1000 - decimal
$100 - hexadecimal
100h - hexadecimal
%100 - binary
'x'  - character

Remember that if you use the suffix 'h' to give a hexadecimal value,
and the value begins with an alphabet, you must place a zero in front of it
so Open8_as knows it's not a label (e.g., "0ah" instead of "ah").


3.5. Strings

Strings begin with and end to '"'. Note that no 0 is inserted to indicate
the termination of the string like in e.g., ANSI C. You'll have to do it
yourself. You can place quotation marks inside strings the way C
preprocessors accept them.

Here are some examples of strings:

"Hello world!"
"He said: \"Please, kiss me honey.\""


----------------------------------------------
4.... Error Messages
----------------------------------------------


There are quite a few of them in Open8_as, but most of them are not very 
informative. Coder beware.


----------------------------------------------
5.... Bugs
----------------------------------------------


Report bugs to jeremy.s.henry.ctr@mail.mil


----------------------------------------------
6.... Temporary Files
----------------------------------------------


Note that Open8 will generate two temporary files while it works. Both files
are placed into the current working directory.

The filenames are ".wla%PID%a" and ".wla%PID%b" (%PID% is the process id).

When Open8 finishes its work these two files are deleted as they serve
of no further use.


----------------------------------------------
7.... Compiling
----------------------------------------------


7.1. Compiling Object Files

To compile an object file use:

"Open8_as -[itvx]o [DEFINITIONS]  [OUTPUT FILE]"

These object files can be linked together (or with library files) later
with "Open8_link".

Name object files so that they can be recognized as object files. Normal
suffix is ".o" (Open8 default). This can also be changed with .OUTNAME.

With object files you can reduce the amount of compiling when editing
small parts of the program. Note also the possibility of using local
labels (starting with "_").

Note! When you compile objects, group 1 directives are saved for linking
time, when they are all compared and if they differ, an error message is
shown. It is advisable to use something like an include file to hold all
the group 1 directives for that particular project and include it to every
object file.

Here are some examples of definitions:

-DIEXIST
-DDAY=10
-DBASE=$10
-DNAME=elvis

And here's an Open8 example creating definitions on the command line:

Open8_as -o -DDEBUG -DVERBOSE=5 -DNAME="math v1.0" math.s

DEBUG's value will be 0, VERBOSE's 5 and NAME is a string definition
with value "math v1.0".


7.2. Compiling Library Files

To compile a library file use:
 
"Open8_as -[itvx]l [DEFINITIONS]  [OUTPUT FILE]"

Name object files so that they can be recognized as library files. Normal
suffix is ".lib" (Open8 default).

With library files you can reduce the amount of compiling. Library files
are meant to hold general functions that can be used in different projects.
Note also the possibility of using local labels (starting with "_").
Library files consist only of FREE sections.


----------------------------------------------
8... Linking
----------------------------------------------


After you have produced one or more object files and perhaps some library
files, you might want to link them together to produce a ROM image / program
file. "Open8_link" is the program you use for that. Here's how you use it:

"Open8_link [-divsS]{b/r}  "

Choose 'b' for program file or 'r' for ROM image linking.

Link file is a text file that contains information about the files you want
to link together. Here's the format:

1. You must define the group for the files. Put the name of the group
inside brackets. Valid group definitions are

[objects]
[libraries]
[header]
[footer]
[definitions]

2. Start to list the file names.

[objects]
main.o
vbi.o
level_01.o
...

3. Give parameters to the library files:

[libraries]
bank 0 slot 1 speed.lib
bank 4 slot 2 map_data.lib
...

Here you can also use "base" to define the 65816 CPU bank number
(like .BASE works in Open8_as):

[libraries]
bank 0 slot 1 base $80 speed.lib
bank 4 slot 2 base $80 map_data.lib
...

You must tell Open8_link the bank and the slot for the library files.

4. If you want to use header and/or footer in your project,
you can type the following:

[header]
header.dat
[footer]
footer.dat

5. If you want to make value definitions, here's your chance:

[definitions]
debug 1
max_str_len 128
start $150
...

If flag 'v' is used, Open8_link displays information about ROM file after a
succesful linking.

If flag 'd' is used, Open8_link discards all unreferenced FREE and SEMIFREE
sections. This way you can link big libraries to your project and Open8_link
will choose only the used sections, so you won't be linking any dead code/data.

If flag 's' is used, a symbol information file is created.
If flag 'S' is used, a symbol information file with breakpoints is created.

If flag 'i' is given, Open8_link will write list files. Note that you must
compile the object and library files with -i flag as well. Otherwise Open8_link
has no extra information it needs to build list files. Here is an example of
a list file: Let's assume you've compiled a source file called "main.s" using
the 'i' flag. After you've linked the result also with the 'i' flag Open8_link
has created a list file called "main.lst". This file contains the source
text and the result data the source compiled into. List files are good for
debugging.

Make sure you don't create duplicate labels in different places in the
memory map as they break the linking loop. Duplicate labels are allowed when
they overlap each other in the destination machine's memory. Look at the
following example:

...
.BANK 0
.ORG $150

        ...
        LD      A, 1
        CALL    LOAD_LEVEL
        ...

LOAD_LEVEL:
        LD      HL, $2000
        LD      (HL), A
        CALL    INIT_LEVEL
        RET

.BANK 1
.ORG 0

INIT_LEVEL:
        ...
        RET

.BANK 2
.ORG $0

INIT_LEVEL:
        ...
        RET
...


Here duplicate INIT_LEVEL labels are accepted as they both point to the
same memory address (in the program's point of view).


----------------------------------------------
9... Arithmetics
----------------------------------------------


Open8_as is able to solve really complex calculations like

-((HELLO / 2) | 3)
skeletor_end-skeletor
10/2.5

so you can write something like

LD HL, data_end-data
LD A, (pointer + 1)
CP (TEST + %100) & %10101010

Open8_link also has this ability so it can compute the pending calculations
Open8_as wasn't able to solve.

The following operators are valid:

(, ), | (or), & (and), ^ (power), << (shift left), >> (shift right), +, -,
# (modulo), ~ (xor), *, /, < (get the low byte) and > (get the high byte).

Note that you can do NOT using XOR:

VALUE_A ~ $FF   = 8bit NOT
VALUE_B ~ $FFFF = 16bit NOT

Open8_as computes internally with real numbers so (5/2)*2 produces 5, not 4.



----------------------------------------------
10... Open8_as Flags
----------------------------------------------


Here are short descriptions for the flags you can give to Open8_as:

You can supply Open8_as with some (or all or none) of the following option flags.

i - Add list file information. Adds extra information to the output so
    Open8_link can produce list files.
M - Open8 generates makefile rules describing the dependencies of the main
    source file. Use only with flags 'o' and 'l'.
q - Quiet mode. .PRINT* -directives output nothing.
t - Test compile. Doesn't output any files.
v - Verbose mode. Shows a lot of information about the compiling process.
x - Extra compile time definitions. Open8_as does extra work by creating
    few helpful definitions on the fly.

One (and only one) of the following command flags must be defined.

l - Output a library file.
o - Output an object file.

Examples:

[seravy@localhost tbp]# Open8_as -voi testa.s
[seravy@localhost tbp]# Open8_as -oM testa.s
[seravy@localhost tbp]# Open8_as -l testb.s testb.lib

Note that the first example produces file named "testa.o".


----------------------------------------------
11... Good things to know about Open8_as
----------------------------------------------


- Is 64 bytes too little for a string (file names, labels, definition labels,
  etc)? Check out "MAX_NAME_LENGTH" in defines.h.
- Open8_as preprocessor doesn't expand macros and repetitions. Those are actually
  traversed in the assembling phase.
- Open8_as's source code is mainly a huge mess, but Open8_link is quite well
  structured and written. So beware!
- Do not write ".E" into your sources as Open8_as uses it internally to mark
  the end of a file.


----------------------------------------------
12... Legal Note
----------------------------------------------

Open8_as and Open8_link is licensed as GPL software, as are any helper programs. 

Code in the examples section is licensed under the BSD license.