Added reference to Bibi-binary

[fifth.git] / doc / index.org

#+TITLE: Fifth - virtual machine, operating system, programming language

* General
- This program is free software: released under Creative Commons Zero
  (CC0) license

- Program author:
  - Svjatoslav Agejenko
  - Homepage: https://svjatoslav.eu
  - Email: mailto://svjatoslav@svjatoslav.eu

- [[https://www.svjatoslav.eu/projects/][Other software projects hosted at svjatoslav.eu]]
** Source code
- [[https://www2.svjatoslav.eu/gitweb/?p=fifth.git;a=snapshot;h=HEAD;sf=tgz][Download latest snapshot in TAR GZ format]]

- [[https://www2.svjatoslav.eu/gitweb/?p=fifth.git;a=summary][Browse Git repository online]]

- Clone Git repository using command:
  : git clone https://www2.svjatoslav.eu/git/fifth.git

* !Project deprecated!
Current implementation does not support object oriented
programming. While working on Fifth I got lots of cool new ideas that
require reimplementation of everything.

Currently I try to implement those new ideas in the project called
[[https://www3.svjatoslav.eu/projects/sixth/][Sixth]].

System is built many years ago when I was still using DOS as a primary
operating system.
* Introduction
Fifth is programming lanquage & operating system, running on [[id:9b251eb9-aff6-4025-94bf-25e89e26d54a][virtual
machine]], with custom instruction set. It is much like Charles Chunk
Moore's Forth, it also uses stack architecture, and many commands are
similar. Basically I got familiar with concepts of Forth, and being
inspired created my own system.

- [[file:5TH_ET.txt][Example Fifth source file - text editor]]
** screenshots
[[file:screenshots/start.png]]

Startup screen diplaying Fifth logo and full file list.

[[file:screenshots/dictionary.png]]

Sample words defined. Most of the words are commands that can be
executed interactively from command line or from file. When executed
they can be selectively compiled or interpreted.


[[file:screenshots/text editor.png]]

Built in text editor.

* Installation
Just unpack all files, witout altering original directory structure,
somewhere in your hard disk. For example: C:\MISC\FIFTH\....  To run
fifth you need minimally just 2 files.  emulator itself ( EMULATOR.EXE
or EMULATOR.COM ), and virtual disk file ( DISK.RAW ).

Read more about [[id:0759f3e0-28bb-4901-9e4f-09ef41732173][Fifth distribution directory tree description]].

* Fifth distribution directory tree description
:PROPERTIES:
:ID:       0759f3e0-28bb-4901-9e4f-09ef41732173
:END:
After downloading and unpacking the ZIP file you shoud get directory
tree similar to this:

#+BEGIN_VERSE
*DOC*                   - Fifth documentation
  *commands*            - documentation on Fifth built-in commands
  *modules*             - documentation on additional commands, realized as loadable modules
  *shots*               - Fifth screenshots

*imageFile*             - files contained within 'disk.raw', just an extracted form.

*source*                - source files
  *emulator*            - emulator source
  *util*                - utilites

*disk.raw*                - Virtual disk file, has filesystem inside.
*emulator.com*            - main executable.
#+END_VERSE

* Requirements
** Software
- MS-DOS 6.22, with HIMEM.SYS loaded.
- Mouse driver if you have a mouse.
- Does work only when CPU is in real mode.
- To recompile ASM sources I used FASM (Flat Assembler).
- I ran QBasic utilities on QB 4.5 .
- VESA support by BIOS, or external driver (UNIVBE).
** Hardware
- Minimum CPU 386.
- 64 KB free RAM below 640KB,
- 2 MB of free XMS.
- VESA compatible video card.
** Human
- Beginner level Forth knowledge is recommended.
- Lots of enthusiasm.
* Numbers representation within Fifth

Because we are in full experimentation mode here (no regard for
compatibility whatsoever), why not to try also alternative number
representation ?

Here alternative hexadecimal number representation format is devised:

[[file:numbers.png][file:numbers.png]]

Essentially square is split into 4 triangles. Each triangle represents
one bit.

Fifth uses this hexadecimal format as primary throughout entire
system.

See also: [[https://en.wikipedia.org/wiki/Bibi-binary][Bibi-binary]].

* Disk file map, and it's data structures
Core and high-level boot code is stored outside of the filesystem to
allow easy access to it, at early booting time, when filesystem is not
yet initialized.
** Disk allocation
| offset | length | description          |
|--------+--------+----------------------|
| 0      | ~4 Kb  | Fifth core           |
| 4 Kb   | ~32 Kb | high-level boot code |
| 37 Kb  | ~65 Kb | FAT                  |
| 101 Kb | ~16 MB | filesystem data area |
** FAT entry format:
| code | meaning                  |
|------+--------------------------|
|   -2 | last sector              |
|   -1 | empty sector             |
| 0 -- | .. pointer to next block |
** File entry format
| offset | length | description            |
|--------+--------+------------------------|
|      0 |      4 | extension              |
|      4 |     16 | name                   |
|     20 |      4 | entry point            |
|     24 |      4 | size                   |
|     28 |      4 | last modification time |
* Core architecture
Fifth core is simply some amount of already compiled into machine code
and linked together modules (entries in other words). In compilation
process modules is compiled one by one and simply stored on top of
already existing and growing core. Separately from core is kept
dictionary, this is special list that contain names of compiled
modules, variables etc. and they locations in core. Constants use
dictionary space only. Random word can be removed from dictionary at
any time. Currently dictionary can contain at most 1000 entries.
** Dictionary entry format
| offset | length | description           |
|--------+--------+-----------------------|
|      0 |      4 | 0 < previous entry |
|        |        | 0 = last              |
|        |        | -1 = empty            |
|--------+--------+-----------------------|
|      4 |     15 | module name string    |
|--------+--------+-----------------------|
|     19 |      1 | entry type            |
|--------+--------+-----------------------|
|     20 |      4 | entry data            |

Core headers as linked list of module names make up something like
dictionary.  When some entry address is needed compiler can quickly
run through headers backwards and find needed entry.
** Possible module types
| type | description    | "execute" action           |
|------+----------------+----------------------------|
|    0 | data           | compile "num" instruction  |
|      |                | with address to module     |
|------+----------------+----------------------------|
|    1 | submodule      | compile "call" instruction |
|      |                | with address to module     |
|------+----------------+----------------------------|
|    2 | imm. submodule | immediately call to module |
** Memory map
| location | size   | description                 |
|----------+--------+-----------------------------|
|        0 | ~4096  | core                        |
|  1500000 | ~32000 | highlevel Fifth boot code   |
|  200000h |        | core startup messages area  |
|  5200000 |        | end of dynamic memory space |
* Virtual machine
:PROPERTIES:
:ID:       9b251eb9-aff6-4025-94bf-25e89e26d54a
:END:
Using CPU emulator slows it down but I shouldn't now think too mutch
about, and waste my time on batteling with problems whitch results on
complex design of PC hardware. Also it allows me to use existing DOS
and resident drivers services in real mode. So I don't need to deal
with hardware too mutch. It also allows me to use all free XMS for
flat code & data storage.

Current emulator emulates 1 CPU. It has 2 stacks, ~50 instructions,
and 4GB flat address space (theoretically).  I'm not sure that DOS
6.22 that I currently prefer can handle more than 64 MB of RAM. While
I tried to keep instructionset simple, I was forced to put in lot of
complex instructions to make it's performance acceptable on
emulator. On actual silicon ~20 instructions is enaugh (I think).

Maybe one day similar system will run directly on custom silicon chip :)


CPU has following registers:
| IP  | instruction pointer  |
| DSP | data stack pointer   |
| RSP | return stack pointer |
** instruction set
*** overview table
Virtual CPU, commands (most of them are avaiable as ordinary commands
in programming language):


|  # | name         | stack footprint                      | description                                                 |
|----+--------------+--------------------------------------+-------------------------------------------------------------|
|  0 | nop          | --                                   | does nothing                                                |
|  1 | halt         | --                                   | halt CPU ( return to DOS on emulator )                      |
|  2 | [[id:820b1b90-4f4c-4ab1-b49f-9b4a52ea2528][kbd@]]         | -- c                                 | read scancode of pressed or released key                    |
|  3 | num <dword>  | -- n                                 | put immidiate number into datastack                         |
|  4 | jmp <dword>  | --                                   | jump to specified code                                      |
|  5 | call <dword> |                                      | jump to specified code, save return address to return stack |
|  6 | 1+           | n -- n+1                             |                                                             |
|  7 | 1-           | n -- n-1                             |                                                             |
|  8 | dup          | n -- n n                             | duplicate top of data stack                                 |
|  9 | drop         | n --                                 | drop last element in data stack                             |
| 10 | if <dword>   | n --                                 | jump to addr if top element was 0                           |
| 11 | ret          |                                      | jump to code, specified in return stack.                    |
| 12 | c@           | addr -- n                            | read byte from memory at specified address                  |
| 13 | c!           | n addr --                            | store byte to specified memory                              |
| 14 | push         | DSTK -> RSTK                         | move top of datastack to returnstack                        |
| 15 | pop          | RSTK -> DSTK                         | move top of returnstack to datastack                        |
| 16 | <unused>     |                                      |                                                             |
| 17 | rot          | n1 n2 n3 -- n2 n3 n1                 | rotate stack elements                                       |
| 18 | disk@        | FromDiskSect ToMem --                | read 1KB from disk into RAM                                 |
| 19 | disk!        | FromMem ToDiskSect --                | write 1KB to disk                                           |
| 20 | @            | addr -- n                            | read 32 bit number from memory                              |
| 21 | !            | n addr --                            | store 32 bit number to memory                               |
| 22 | over         | n1 n2 -- n1 n2 n1                    |                                                             |
| 23 | swap         | n1 n2 -- n2 n1                       |                                                             |
| 24 | +            | n1 n2 -- n1+n2                       |                                                             |
| 25 | -            | n1 n2 -- n1-n2                       |                                                             |
| 26 | *            | n1 n2 -- n1*n2                       |                                                             |
| 27 | /            | n1 n2 -- n1/n2                       |                                                             |
| 28 | >            | n1 n2 -- result                      | is true when n1 > n2                                        |
| 29 | <            | n1 n2 -- result                      | is true when n1 < n2                                        |
| 30 | not          | n1 -- not_n1                         | logical not                                                 |
| 31 | i            | -- n                                 | copies top of return stack into datastack                   |
| 32 | cprt@        | addr -- n                            | read one byte from hardware port                            |
| 33 | cprt!        | n addr --                            | store one byte to hardware port                             |
| 34 | i2           | -- n                                 | like "i" but takes second top stack element                 |
| 35 | i3           | -- n                                 | like "i" but takes third top stack element.                 |
| 36 | shl          | n amount -- n                        | left bit shift                                              |
| 37 | shr          | n amount -- n                        | right bit shift                                             |
| 38 | or           | n1 n2 -- n                           | logical or                                                  |
| 39 | xor          | n1 n2 -- n                           | exclusive logical or                                        |
| 40 | vidmap       | addr --                              | copy memory from "addr" to video memory.                    |
| 41 | mouse@       | -- x y button                        | read mouse coordinates & buttons                            |
| 42 | [[id:238e8b03-57b6-424d-bfee-b6bb652cefbc][vidput]]       | addr1 addr2 x y --                   | put image1 into image2, at location x, y                    |
| 43 | [[id:79e1916f-4103-42cc-ac10-bb1ee776ed50][cmove]]        | addr1 addr2 amount                   | move memory from addr1 to addr2                             |
| 44 | cfill        | c addr amount --                     | fill memory starting at "addr" with "c" bytes.              |
| 45 | [[id:ab45247c-44c3-464d-9e2a-337f483b4616][tvidput]]      | addr1 addr2 x y --                   | put image with transparency support                         |
| 46 | depth        | -- depth                             | returns current depth of data stack.                        |
| 47 | [[id:4bb479cf-aae0-4128-9868-f016c286a162][charput]]      | colorfg colorbg addrsrc addrdest x y | draw text character                                         |

*** kbd@ - read scancode of pressed or released key
:PROPERTIES:
:ID:       820b1b90-4f4c-4ab1-b49f-9b4a52ea2528
:END:
Returns 0 if no data available.
*** vidput - put image1 into image2, at location x, y
:PROPERTIES:
:ID:       238e8b03-57b6-424d-bfee-b6bb652cefbc
:END:
Does clipping, so part of a big image can be mapped into smaller one.
*** cmove - copy memory array
:PROPERTIES:
:ID:       79e1916f-4103-42cc-ac10-bb1ee776ed50
:END:
Move memory from addr1 to addr2. If addr1 is greater than addr2 then
count address foward while moving, elseway starts from end and counts
backwards, so no data loss occurs when memory regions partially
overlap.
*** tvidput - put image with transparency support
:PROPERTIES:
:ID:       ab45247c-44c3-464d-9e2a-337f483b4616
:END:
Stack footprint
: addr1 addr2 x y --

Put image1 into image2, at location x, y with transparency support

Color 255 in source image is treated as transparent.
*** charput - draw text character
:PROPERTIES:
:ID:       4bb479cf-aae0-4128-9868-f016c286a162
:END:
Draw character to image buffer located at "addrdest" to specified x &
y location. Decodes 8 bytes from source to bits, used to draw
character.

* Fifth source format
Fifth uses a different character table and codes than ASCII (still
almost similar). I call it FSCII (Fifth Standard Code for Information
Interchange) for example space character is not 32 but 255 instead.  I
plan to use mainly HEX numbers, and create new characters to represent
numeric values. So typical nemric characters "0123..."  is treated
like ordinary letters.
** FSCII

|    DEC | HEX   | function                               |
|--------+-------+----------------------------------------|
| 0 - 15 | 0 - F | HEX numbers                            |
|    252 | FC    | backspace                              |
|    253 | FD    | tabulator (TAB)                        |
|    254 | FE    | carriage return (CR)                   |
|    255 | FF    | space                                  |
|   else |       | ordinary characters, same as in ASCII. |
* Fifth commands
** Compilation & miscellaneous
#+BEGIN_VERSE
init    module  ( -- )
                First module, control is passed to on startup. Contains
                initialization routines. Also it is the last core module.
                All new modules on top of it comes as result of executing
                external source files.

head <name>     ( -- )  compiles new dictionary entry without specifying
                new module type.
                ex: head myentry

: <name>        ( -- )  creates new code module
;               ( -- )  ends module (immideate)
                ex: : hello ." hi there" ;

const <name>    ( n -- ) defines new constant.
                ex: 2147483647 const max

:i <name>       ( -- ) same as ":" but this module will be executed
                immideately even in compile mode.
                ex: :i ( 41 scan ;

create <name>   ( -- ) same as "head" , but specify module type as data.
                ex: create LotoResults 5 , 13 , 52 , 12 , 11 , 3 ,

allot           ( n -- ) allocate n bytes in dictionary.
                ex: create MyArray 100 allot

" <string>"     ( -- ) compile string and its size into core.
                ex: create Mystring " This is it's contects"

str <name> <string>" ( -- ) just shorter way for defining strings.
                ex: str Mystring This is it's contenc"

var <name>      ( -- ) define new 32 bit variable.
                ex: var result

' <module>      ( -- n ) return memory address of given entry.
                ex: ' init

forget <name>   ( -- ) erases from RAM given entry and all entries what was
                defined after it.
                ex: forget myprog

[               ( -- )  set interpret mode (immideate)
]               ( n -- ) set compile mode and compile top stack element
                in as literal. Together [ .... ] cobination provides good
                way to compute some values only once, at compile time,
                rather than every time while program is running.
                ex: : calculate - [ 4 MyConst1 + MyConst2 * ] ;

defer <name>    ( -- ) creates new module, with jump instruction.
                Later address where to jump can be modified by "is" command.
                This provides method of foward referencing. So you can use
                modules what not jet exist.
is              ( address1 address2 -- ) address1 - where to jump, address2 -
                address of module created by defer command.
                ex:     defer dispver
                        : run dispver ." running ..." ;
                               ... whatever ...
                        : (dispver ." Version 9.99 " ;
                        ' (dispver ' dispver is

                Now if I type "run" on the screen appears:
                        Version 9.99 running ...

asc <char>      ( -- ) reads char ascii code and treats it as literal.
                (immideate)
                ex: : BreakLine 30 do asc - emit loop ;
                                 same as:
                    : BreakLine 30 do    45 emit loop ;

dyninc          ( handle -- ) execute code in dynamic memory handle.
                automatically deallocates it when done.

include         ( filenumber -- ) execute code in specified file.

words           ( -- ) display existing blocks in core.

bye             ( -- ) exit from Fifth

fkey            ( -- c )
                Read one byte from input stream.

sadd            ( c addr -- )
                Add one byte "c" to string located at "addr" and updates
                string length.

scan            ( c -- )
                Read input stream and store it to  pad   until it finds  c  .
                It ignores all "c" bytes until it finds any non "c" byte.
                in other words:
                                c  is:  "
                         input stream:  """"This is test !"aoeu idh
                               result:  This is test !

                Is useful for breaking text lines into words.

skey            ( -- c )
                So called safe "fkey". Reads data from input stream
                but converts characters with ASCII codes: 9 13 10
                to spaces.

str=str?        ( adr1 adr2 -- result )
                Compares string at "adr1" with string at "adr2", returns
                true flag if they are equal or false if they are not.
                true = -1
                false = 0

find            ( -- addr )
                Searches whole dictionary for word in "pad". If found,
                returns it address, if not, returns 0.

execute         ( -- )
                Execute word located in "pad". Depending on "mode".

dta             ( addr -- DataAddr )
                Calculates address of dictionary entry data area, from
                entry point.

2num            ( -- num result )
                Attempt to convert string located in "pad" into numeric
                value. If succeed returns number and true as result.
                If not, returns whatever and false as result.

dadd            ( addr length -- )
                Add to dictionary data located at "addr", with specified
                length.

lit             ( n -- )
                Act with number depending on "mode". When interpreting,
                leaves it in stack.


incmod          ( addr -- )
                Add to dictionary data located at "addr"+1 , length is taken
                from "addr".

here            ( -- n )
                return "h" contents.

mode    var     8 bit
                Holds input stream parser operation mode.
                0 = interpreting
                1 = compiling

pad     var     128 bytes
                Holds temprorary strings.

h       var     32 bit
                Pointer to free byte in memory, always at the end of the
                dictionary. Each time when something is stored
                by "c," command, pointer is incareased.

lp      var     32 bit
                Pointer to last dictionary word. Each time when new word is
                compiled or erased by "forget", this pointer is updated.

modulechk       ( Dstr<filename> -- ) check if module is loaded, if not
                immideately load it.

ne              ( entrydata entrytype -- ) Compile new dictionary entry.
                It's name must be in "pad".
#+END_VERSE
** Conditionals & control flow
#+BEGIN_VERSE
if              ( flag -- )   (immideate)
                "if 1.. else 2.. then" or
                "if 1.. then" construction. Conditional execution.
                Performs "1.." if "flag" was true,
                elseway performs "2.." if exist. Execution continues after
                word "then".
                ex: 1 if ." nonzero" else ." zero" then

>=              ( n1 n2 -- result ) true if (n1 = n2) or (n1 > n2)
                ex: 5 3 >= if ." first number is greater or equal" then

<=              ( n1 n2 -- result ) true if (n1 = n2) or (n1 < n2)
=               ( n1 n2 -- result ) true if n1 = n2

do              ( count -- )  (immideate)
                "do .. loop" construction. Performs ".." "count" times.
                In every step "count" is decareased until it is 0.
                ex: : test 5 do i .d loop ;
                result: 4 3 2 1 0

doexit         ( -- ) exit from "do .. loop"

for             ( count top -- )   (immideate)
                "for .. loop" construction. Performs ".." (top - count)  times.
                In every step "count" is incareased until it reaches "top" .
                ex: : test 4 10 for i .d loop ;
                result: 4 5 6 7 8 9

forexit         ( -- ) exit from "for .. loop"

until           ( -- )  (immideate)
                "until .. loop" construction. Performs ".." until flag become
                true. False by default. Top of return stack holds flag.

done            ( -- ) exit from "until .. loop"

#+END_VERSE
** Disk & file access
#+BEGIN_VERSE
diskload ( FromDisk ToMem amount -- )
                Load specified abount of bytes from disk into memory.

disksave ( FromMem ToDisk amount -- )
                save specified abount of bytes from memory into disk.

format ( -- )   Erase all files.

fsDfilesize@ ( handle -- size )
                Return size of opened file.

fsDcurloc@ ( handle -- location )
                Return current location in file.

fsDupdated@ ( handle -- updated? )
                Return true if file was updated,
                ie. write operations occured.

fssave ( FromMem DestFileHandle amount -- )
                Save data to file.

fsload ( SrcFileHandle ToMem amount -- )
                Load data from file.

fseof ( handle -- bytesLeft )
                Return amount of bytes left till end of file.
                Useful before read operation.

fsls ( -- )     List all files and lists (directories,folders)
                in current path.

fslsr ( -- )    Same as "fsls" but recursively scans also sub lists.

fscl ( DynStrHand -- )
                Change list (path)

fscreate ( DynStrHand -- DescPnt )
                Create new file or list. Can create multiple lists at once.
                ex: when creating:
                    "\listGAMES\listSTRATEGY\listSIMWORLD\5th-runme"
                and only "\listGAMES\" already exist, then
                "listSTRATEGY" and "listSIMWORLD" lists will be created,
                and empty file "5th-runme" placed in there.

fsDsave ( DynHand<data> DynStrHand<filename> -- )
                Create new file and save all data from dynamic memory
                block to it.

fsDload ( DynStr<SrcFileName> DynHand<DataDest> -- )
                Load whole file into dynamic memory block.

fsDloadnew ( DynStr<SrcFileName> -- DynHand<DataDest> )
                Load whole file into new dynamic memory block.
#+END_VERSE
** Dynamic memory
#+BEGIN_VERSE
dynal ( size -- handle )
                Allocate dynamic memory block and return it's handle.

dynde ( handle -- )
                Deallocate dynamic memory block.

dynp ( handle -- addr )
                Returns pointer to memory where dynamic block
                data begins.

dyns ( handle -- size )
                Returns size of dynamic block.

dynresize ( NewSize handle -- )
                Nondestructively resize dynamic block.

dync@ ( addr handle )
                Read one byte from dynamic block.

dync! ( byte addr dynhandle )
                Write one byte to dynamic block.

dyn@ ( addr handle )
                Read 32 bit number from dynamic block.
                Address will spacify, whitch number, not byte.

dyn! ( 32BitNum addr dynhandle )
                Write 32 bit number to dynamic block.
                Address will spacify, whitch number, not byte.

dyncon ( size "name" -- )
                Allocate dynamic block with specified size, and
                create constant honding its handle.
                ex: 100 dyncon MyNewBlock

dyn. ( handle -- )
                Write contenc of dynamic memory block to screen.
#+END_VERSE
** Graphics and text
#+BEGIN_VERSE
.               ( n -- ) print number on screen

d.              ( n -- ) print number on screen in decimal

?               ( addr -- ) print 32 bit value located at addr.

." <string>"    ( -- ) print string into screen. Immideately
                compiles.
                ex: : greeting ." Hello, World" ;

tab.            ( -- ) print tabulator

calccol         ( b g r -- c ) calculate color what best matches given
                Blue Green & Red values. Values must be in range 0 - 255.

imgalloc        ( xsize ysize -- imgbuf ) allocate image buffer for
                specified size.

imgsize         ( imgbuf -- ) print on the screen X & Y size of image
                buffer.

point           ( x y imgbuf -- addr ) returns memory address for specified
                pixel.

pset            ( color x y imgbuf -- ) set graphic point

boxf            ( x1 x2 y1 y2 imgbuf color -- ) draw filled box

cls             ( imgbuf -- ) clear image buffer

setpal          ( b g r color -- ) set palette value for specified color.
                values bust be in size 0 - 63.

putchar         ( char color x y imgbuf -- ) put graphic character in
                imagebuffer to specified (x & y) location.

scroll          ( x y imgbuf -- ) scroll in imgbuf.

scrollf         ( color x y screen -- )  scroll and fill empty space with
                given color.

at!             ( x y -- ) set cursor location
curc!           ( color -- ) set text color
curb!           ( solor -- ) set backround color

colnorm         ( -- ) set text color to normal
colneg          ( -- ) set text color to negative (selected)

dyntype         ( dynhandle -- ) display contenc of dynamic memory on screen
fsdisp          ( file -- ) clear screen, display file, and wait for key

type            ( addr length -- )
                Types on the screen string, from memory at  addr  and
                specified length.

write           ( addr -- )
                Types on the screen string, from memory at "addr"+1
                length is taken from "addr" .

screen  const   32 bit
                Holds handle of screen buffer.

copyscreen      ( SrcImgHandle DestImgHandle -- ) copy contenc of source
                image to destination image. Source and destination images
                must have same size.
#+END_VERSE
** Math, memory & stack manipulation
#+BEGIN_VERSE
off             ( n -- ) writes 0 to given address, good for zeroing variable.
                ex: MyVariable off
on              ( n -- ) writes -1 (true flag) to given address.
                ex: MyVariable on

2dup            ( n1 n2 -- n1 n2 n1 n2 )
2drop           ( n1 n2 -- )
nip             ( n1 n2 -- n2 )
neg             ( n1 -- -n1 ) negotiate
bit@            ( n bit -- result ) return specified bit from n.
                ex: 38 2 bit@   (result will be 1)
to32bit         ( n1 n2 n3 n4 -- n32 ) treat 4 last stack elements as bytes
                and unite them into 32 bit dword. Most significant byte
                on top.
                ex: 12 76 23 11 to32bit   result: 186076172

to8bit          ( n32 -- n1 n2 n3 n4 ) break 32 bit number into 4 bytes.
                Useful if you need to send 32 bit numbers thru 8 bit COM
                port.
                ex: 186076172 to8bit   result: 12 76 23 11

mod             ( n1 n2 -- reminder ) divide n1 by n2 and returns reminder.
                ex: 12 5 mod   result: 2

bound           ( low n high -- n ) check if n is in given bounds,
                if not then incarease/decarease it to match bounds.
                ex: 5 80 15 bound    result: 15
                    5 10 15 bound    result: 10
                    5 -10 15 bound   result: 5

bound?          ( low n high -- result ) returns true if n is in the
                given bounds.

tab             ( col -- spaces) calculate amount of spaces to add
                ta reach next tabulation from given column.

count           ( addr -- addr+1 n )
                Useful for returning bytes from constantly incareasing
                address. Module "type" is nice example.

c,              ( n -- )
                store one byte at memory specified by "h". And incarease
                "h" by 1.

,               ( n -- )
                store 32 bit number at memory specified by "h". And
                incarease "h" by 4.

cmove           ( addr1 addr2 n -- )
                copy "n" amount of bytes from memory at "addr1" to memory
                at "addr2".

rnd             ( limit -- result )
                generates random number in range 0 to "limit"-1.

abs             ( n -- |n| )
                returns absolute value of "n"
#+END_VERSE
** Dynamic & static strings
Fifth supports both static and dynamic strings. Static strings must
have predefined space reserved, and string mustn't exceed this
length. They manipulation is faster. But they use more memory. Static
string memory address is used to refer to the string.

Dynamic strings can have at any time length form 0 to 0FFh, They take
up only memory they currently need. They are held in dynamic memory
blocks, so dynamic block handle is used to refer to this string.

Both types of strings are stored in the way, where first (0th) byte
holds current string length, following bytes are string itself.


#+BEGIN_VERSE
Dynamic:

Dstral ( -- handle )
                Allocate new string.

Dstrlen ( handle -- length )
                Return string length.

c+Dstr ( chr handle -- )
                Add one byte to end of the string.

c+lDstr ( chr handle -- )
                Add one byte to left side (beginning) of the string.

Dstr. ( handle -- )
                Write contec of string into screen.

Dstrsure ( size Dstr -- )
                Makes sure that at least rquested
                "size" (amount of characters) is allocated for given
                dynamic string.

Dstr2str ( handle address -- )
                Copy dyamic string into static memory space.

str2Dstr ( address handle -- )
                Copy static string into dyamic string.

Dstr+str ( Dstr addr -- )
                Add contenc of dynamic string to static string.

D" any string" ( -- Dstr )
                Moves specified string into dynamic string called "defDstr".

D> any_string ( -- Dstr )
                Moves specified string into dynamic string called "defDstr".
                Space marks end of string!

D>2 any_string ( -- Dstr )
                Moves specified string into dynamic string called "defDstr2".
                Space marks end of string!

Dstr+Dstr ( Dstr1 Dstr2 -- )
                Adds "Dstr1" to "Dstr2" and places result into "Dstr2".

Dstrclear ( Dstr -- )
                Clears contenc of dynamic string.

Dstr2Dstr ( Dstr1 Dstr2 -- )
                Moves "Dstr1" to "Dstr2".
Dstr ( data" name -- )
                Creates new dynamic string and moves specified data into it.
                Then creates new constant with given "name" holding created
                dynamic string handle.

                ex: Dstr Hello, my name is Sven!" message      \ creates it
                    message Dstr.                              \ tests it

Dstrlscan ( char Dstr -- loc )
                Searches dynamic string for "char", from left to right,
                returns first found "char" location in string, or 0,
                if not found.

Dstrrscan ( char Dstr -- loc )
                Searches dynamic string for "char", from right to left,
                returns first found "char" location in string, or 0,
                if not found.

Dstrlscane ( char Dstr -- loc )
                Same as "Dstrlscan" buf returns string length+1 as location.
ÿ
Dstrleft ( amo Dstr -- )
                Only specified amount of characters from left remains
                in dynamic string. ie. cut right part out.

Dstrright ( amo Dstr -- )
                Only specified amount of characters from right remains
                in dynamic string. ie. cut left part out.

Dstrcutl ( amo Dstr -- )
                Cut specified amount of characters from left of dynamic
                string out.

Dstrsp ( char Dstr1 Dstr2 -- )
                Separate dynamic string in Dstr1 into two parts,
                using "char" as separator. First part will be stored in
                "Dstr2", second part in "Dstr1".
                ex: asc \                               \ ..separator
                    D> listF\listLIB\5TH_DRVMOUSE       \ ..separate from
                    defDstr2                            \ ..place result in
                    Dstrsp              \ separation command
                    defDstr Dstr.       \ will be: listLIB\5TH_DRVMOUSE
                    defDstr2 Dstr.      \ will be: listF

Dv ( addr -- )
                Allocates empty dynamic string, and places it's handle
                into given address.

Df ( addr -- )
                Reads dynamic string handle from given address and
                deallocates (frees) it.

ex:     var mystring1
        : testmodule
        mystring1 Dv            \ allocates string

                <whatever>

        mystring1 Df ;          \ deallocates it again when no longer needed.
#+END_VERSE
* Dynamically loadable modules
** Keyboard driver
#+BEGIN_VERSE

KBD_@           ( -- code ) get scancodes for pressed keys from keyboard.
KBD_down?       ( key -- result ) check is key with specified scancode
                currently pressed down.
KBD_SC2FSCII    ( code -- FSCII ) convert key scancode into FSCII code,
                or in FSK (Fifth standard keycode).
KBD_F@          ( -- FSCII ) read pressed key FSCII or FSK, returns -1 if no
                keys are pressed.
KBD_FW@         ( -- FSCII ) read pressed key FSCII or FSK, if no keys is
                are pressed then waits until there is.

                FSK
                ---
In HEX.

FC      backspace
FD      TAB
FE      enter
FF      space

400     ESC
401 ... F1 ...
410     up
411     right
412     down
413     left
414     INS
415     DEL
416     home
417     end
418     PG/UP
419     PG/DN
#+END_VERSE
** Mouse driver
#+BEGIN_VERSE
mousex  var     Mouse x coordinate.
mousey  var     Mouse y coordinate.
mousekeyl var   Mouse left key.
mousekeym var   Mouse middle key.
mousekeyr var   Mouse right key.
mousec  var     Display current mouse coordinates in top left part of screen,
                if true. (good for debugging)
mousepointer var  Image buffer, holding current mouse pointer.
mouseadd        ( ModuleAddr x1 x2 y1 y2 -- ) Add specified area on screen,
                into mause click buffer. If any mouse button is clicked on
                that area, module at "ModuleAddr" will be executed.
mousebe var     Amount of buffer elements.
mousedo         ( -- ) Updates mouse coordinates and keys. Parse mouse
                click buffer, and draw mouse cursor to "screen".
#+END_VERSE
** 2D graphic library

+ lineh ( color len x y imgbuf -- ) :: draws horisontal line from X,Y
  coordinates to right, with specified length.

+ linev ( color len x y imgbuf -- ) :: draws vertical line down, from
  coordinates X,Y, with specified length.

+ box ( color x2 x1 y2 y1 imgbuf -- ) :: draws rectangular box. x2
  bust be >= x1, y2 must be >= y1.

  #+begin_example
    x1,y1-----------+
      |             |
      |             |
      +-----------x2,y2
  #+end_example

+ flipv ( imgbuf -- ) :: flip image vertically.

+ imgcoltrans ( ImgBuf Color ToColor -- ) :: Translate all pixels in
  specified image with "Color" into "ToColor".

+ imgfill ( color x y imgbuf -- ) :: Fill image region starting at
  location X & Y with specified color.


** Trigonometry functions
*** sin ( a -- result )
:PROPERTIES:
:ID:       9a66ca9c-eb5f-45aa-8116-71763081f2fb
:END:
Return sinus from given angle "a", 360ø is 2000. So 1000 represents
180ø angle.  Result will be in range -10'000 to 10'000, instead of ñ1.
*** cos ( a -- result )
Return cosinus from given angle.  Parameters are like in [[id:9a66ca9c-eb5f-45aa-8116-71763081f2fb][sin]] function.