What is ficl?

• Target 32 bit processors (version 2.03 targets 64 bit processors too)
• Scripting, prototyping, and extension language for systems written also in C
• Supportable - code is as transparent as I can make it
• Interface to functions written in C
• Conform to the Forth DPANS 94
• Minimize porting effort - require an ANSI C runtime environment and minimal glue code
• Provide object oriented extensions

DISCLAIMER OF WARRANTY and LICENSE

Any third party may reproduce, distribute, or modify the ficl software code or any derivative works thereof without any compensation or license, provided that the original author information and this disclaimer text are retained in the source code files. The ficl software code is provided on an "as is" basis without warranty of any kind, including, without limitation, the implied warranties of merchantability and fitness for a particular purpose and their equivalents under the laws of any jurisdiction. 

The FiclWin distribution, a derivative work of the ficl source code, is hereby licensed for unrestricted non-commercial use under the ficl license provided the user notifies the author (John Sadler) in writing or by electronic mail or their intended use of the FiclWin sources. You may freely redistribute the FiclWin distribution provided it contains this notice and adheres to all other provisions of this license. 

Reselling the FiclWin source code, executable, or works derived from the FiclWin source code is prohibited under this license. Please contact me directly in order to discuss license terms for commercial use and distribution.

I am interested in hearing from anyone who uses ficl. If you have a problem, a success story, a defect, an enhancement request, or if you would like to contribute to the ficl release, please send me email. 

Ficl features

• Code is written in ANSI C for portability. 
• Standard: Implements the ANS Forth CORE word set, part of the CORE EXT word set, SEARCH and SEARCH EXT, TOOLS and part of TOOLS EXT, LOCAL and LOCAL EXT, EXCEPTION, MEMORY,  and various extras.
• Extensible: you can export code written in Forth, C, or asm in a straightforward way. Ficl provides open facilities for extending the language in an application specific way. You can even add new control structures (not surprising if you're familiar with Forth)
• Ficl and C can interact in two ways: Ficl can wrap C code, and C functions can invoke ficl code.
• Ficl code is thread safe and re-entrant:  All Ficl VMs share one system dictionary; each Ficl virtual machine has an otherwise complete state, and each can be bound to a separate I/O channel (or none at all). An optional function called ficlLockDictionary() can control exclusive dictionary access. This function is stubbed out by default (See FICL_MULTITHREAD in sysdep.h). As long as there is only one "session" that can compile words into the dictionary, you do not need exclusive dictionary access for multithreading. Note: while the code is re-entrant, there are still restrictions on how you can use it safely in a multithreaded system. Specifically, the VM itself maintains state, so you generally need a VM per thread in a multithreaded system. If interrupt service routines make calls into Ficl code that alters VM state, then these generally need their own VM as well. Alternatively, you could provide a mutual exclusion mechanism to serialize access to a VM from multiple threads.
• Simple incorporation into existing systems: the sample implementation requires three Ficl function calls (see the example program in testmain.c).
• ROM able: Ficl is designed to work in RAM based and ROM code / RAM data environments. It does require somewhat more memory than a pure ROM implementation because it builds its system dictionary in RAM at startup time.
• Written an ANSI C to be as simple as I can make it to understand, support, debug, and port. Compiles without complaint at /Az /W4 (require ANSI C, max. warnings) under Microsoft VC++
• Does full 32 bit math (but you need to implement two mixed precision math primitives (see sysdep.c))
• Type 1 indirect threaded interpreter

Porting ficl

Feel free to stub out the double precision math functions (which are presently implemented as inline assembly because it's so easy on many 32 bit processors) with kludge code that only goes to 32 bit precision. In most applications, you won't notice the difference. If you're doing a lot of number crunching, consider implementing them correctly. 

Build controls

Soft Words

To-Do List (target system dependent words)

• Unimplemented system dependent CORE word: KEY (implement this yourself if you need it)
• Kludged CORE word: ACCEPT (implement this better if you need to)

Application Programming Interface

void ficlInitSystem(int nDictCells)

Initializes Ficl's shared system data structures, and creates the dictionary allocating the specified number of CELLs from the heap (by a call to ficlMalloc)

void ficlTermSystem(void)

Reclaims memory allocated for the ficl system including all dictionaries and all virtual machines created by vmCreate. Any uses of the memory allocation words (allocate and resize) are your problem.

int ficlBuild(char *name, FICL_CODE code, char flags)

Create a primitive word in ficl's main dictionary with the given name, code pointer, and properties (immediate, compile only, etc) as described by the flags (see ficl.h for flag descriptions of the form FW_XXXX)

int ficlExec(FICL_VM *pVM, char *text)

Feed the specified C string ('\0' terminated) to the given virtual machine for evaluation. Returns various exception codes (VM_XXXX in ficl.h) to indicate the reason for returning. Normal exit condition is VM_OUTOFTEXT, indicating that the VM consumed the string successfully and is back for more. ficlExec calls can be nested, and the function itself is re-entrant, but note that a VM is static, so you have to take reasonable precautions (for example, use one VM per thread in a multithreaded system if you want multiple threads to be able to execute commands).

int ficlExecC(FICL_VM *pVM, char *text, int nChars)

Same as ficlExec, but takes a count indicating the length of the supplied string. Setting nChars to -1 is equivalent to ficlExec (expects '\0' termination).

int ficlExecXT(FICL_VM *pVM, FICL_WORD *pFW)

Same as ficlExec, but takes a pointer to a FICL_WORD instead of a string. Executes the word and returns after it has finished. If executing the word results in an exception, this function will re-throw the same code if it is nested under another ficlExec family function, or return the exception code directly if not. This function is useful if you need to execute the same word repeatedly - you save the dictionary search and outer interpreter overhead.

void ficlFreeVM(FICL_VM *pVM)

Removes the VM in question from the system VM list and deletes the  memory allocated to it. This is an optional call, since ficlTermSystem will do this cleanup for you. This function is handy if you're going to do a lot of dynamic creation of VMs.

FICL_VM *ficlNewVM(void)

Create, initialize, and return a VM from the heap using ficlMalloc. Links the VM into the system VM list for later reclamation by ficlTermSystem.

FICL_WORD *ficlLookup(char *name)

Returns the address (also known as an XT in this case) of the specified word in the main dictionary. If not found, returns NULL. The address can be used in a call to ficlExecXT.

FICL_DICT *ficlGetDict(void)

Returns a pointer to the main system dictionary, or NULL if the system is uninitialized.

FICL_DICT *ficlGetEnv(void)

Returns a pointer to the environment dictionary. This dictionary stores information that describes this implementation as required by the Standard.

void ficlSetEnv(char *name, UNS32 value)

Enters a new constant into the environment dictionary, with the specified name and value.

void ficlSetEnvD(char *name, UNS32 hi, UNS32 lo)

Enters a new double-cell constant into the environment dictionary with the specified name and value.

FICL_DICT *ficlGetLoc(void)

Returns a pointer to the locals dictionary. This function is defined only if FICL_WANT_LOCALS is #defined as non-zero (see sysdep.h). The locals dictionary is the symbol table for local variables.

void ficlCompileCore(FICL_DICT *dp)

Defined in words.c, this function builds ficl's primitives. 

void ficlCompileSoftCore(FICL_VM *pVM)

Defined in softcore.c, this function builds ANS required words and ficl extras by evaluating a text string (think of it as a memory mapped file ;-) ). The string itself is built from files in the softwords directory by PERL script softcore.pl. 

 Ficl Source Files

Ficl extras

Number syntax

You can precede a number with "0x", as in C, and it will be interpreted as a hex value regardless of the value of BASE. Example: 

ok> decimal 123 . cr 

123 
ok> 0x123 . cr
291
ok> 0x123 x. cr
123

Search order words

Ficl implements many of the search order words in terms of two primitives called >SEARCH and SEARCH>. As their names suggest (assuming you're familiar with Forth), they push and pop the search order stack. 
The standard does not appear to specify any conditions under which the search order is reset to a sane state. Ficl resets the search order to its default state whenever ABORT happens. This includes stack underflows and overflows. QUIT does not affect the search order. The minimum search order (set by ONLY) is equivalent to 

FORTH-WORDLIST 1 SET-ORDER

There is a default maximum of 16 wordlists in the search order. This can be changed by redefining FICL_DEFAULT_VOCS (declared in sysdep.h). 

Note: Ficl resets the search order whenever it does ABORT. If you don't like this behavior, just comment out the dictResetSearchOrder() lines in ficlExec(). 
 

>search   ( wid -- )

Push wid onto the search order. Many of the other search order words are written in terms of the SEARCH> and >SEARCH primitives. This word can be defined in ANS Forth as follows

: >search   >r get-order 1+ r> swap set-order ;

search>   ( -- wid )

Pop wid off the search order (can be coded in ANS Forth as  : search>  get-order nip 1- set-order ; )

ficl-set-current   ( wid -- old-wid )

Set wid as compile wordlist, leaving the previous compile wordlist on the stack

ficl-vocabulary   ( nBins "name" -- )

Creates a ficl-wordlist with the specified number of hash table bins, binds it to the name, and associates the semantics of vocabulary with it (replaces the top wid in the search order list with its own wid when executed)

ficl-wordlist   ( nBins -- wid )

Creates a wordlist with the specified number of hash table bins, and leaves the address of the wordlist on the stack. A ficl-wordlist behaves exactly as a regular wordlist, but it may search faster depending on the number of bins chosen and the number of words it contains at search time. As implemented in ficl, a wordlist is single threaded by default. ficl-named-wordlist takes a name for the wordlist and creates a word that pushes the wid. This is by contrast to VOCABULARY, which also has a name, but replaces the top of the search order with its wid.

forget-wid   ( wid -- )

Iterates through the specified wordlist and unlinks all definitions whose xt addresses are greater than or equal to the value of HERE, the dictionary fill pointer. 

hide   ( -- current-wid-was )

Push the hidden wordlist onto the search order, and set it as the current compile wordlist (unsing ficl-set-current). Leaves the previous compile wordlist ID. I use this word to hide implementation factor words that have low reuse potential so that they don't clutter the default wordlist. To undo the effect of hide, execute  previous set-current

hidden   ( -- wid )

Wordlist for storing implementation factors of ficl provided words. To see what's in there, try:  hide words previous set-current

wid-get-name   ( wid -- c-addr u )

Ficl wordlists (2.05 and later) have a name property that can be assigned. This is used by ORDER to list the names of wordlists in the search order. 

wid-set-name   ( c-addr wid -- )

Ficl wordlists (2.05 and later) have a name property that can be assigned. This is used by ORDER to list the names of wordlists in the search order. The name is assumed to be a \0 terminated string (C style), which conveniently is how Ficl stores word names.  See softwords/softcore.fr definition of brand-wordlist 

wid-set-super   ( wid -- )

Ficl wordlists have a parent wordlist pointer that is not specified in standard Forth. Ficl initializes this pointer to NULL whenever it creates a wordlist, so it ordinarily has no effect. This word sets the parent pointer to the wordlist specified on the top of the stack. Ficl's implementation of SEARCH-WORDLIST will chain backward through the parent link of the wordlist when searching. This simplifies Ficl's object model in that the search order does not need to reflect an object's class hierarchy when searching for a method. It is possible to implement Ficl object syntax in strict ANS Forth, but method finders need to manipulate the search order explicitly.

User variables

user   ( -- ) name

Create a user variable with the given name. User variables are virtual machine local. Each VM allocates a fixed amount of storage for them. You can change the maximum number of user variables allowed by defining FICL_USER_CELLS on your compiiler's command line. Default is 16 user cells. User variables behave like VARIABLEs in all other respects (you use @ and ! on them, for example). Example:

user current-class

0 current-class !

Miscellaneous

-roll   ( xu xu-1 ... x0 u -- x0 xu-1 ... x1 ) 

Rotate u+1 items on top of the stack after removing u. Rotation is in the opposite sense to ROLL

-rot   ( a b c -- c a b )

Rotate the top three stack entries, moving the top of stack to third place. I like to think of this as 1¹/₂swap because it's good for tucking a single cell value behind a cell-pair (like an object). 

.env   ( -- )

List all environment variables of the system

.hash   ( -- )

List hash table performance statistics of the wordlist that's first in the search order

.ver   ( -- )

Display ficl version ID

>name   ( xt -- c-addr u )

Convert a word's execution token into the address and length of its name

body>   ( a-addr -- xt )

Reverses the effect of CORE word >body (converts a parameter field address to an execution token)

compile-only

Mark the most recently defined word as being executable only while in compile state. Many immediate words have this property.

empty   ( -- ) 

Empty the parameter stack

endif

Synonym for THEN

last-word   ( -- xt )

Pushes the xt address of the most recently defined word. This applies to colon definitions, constants, variables, and words that use create. You can print the name of the most recently defined word with 

last-word >name type 

parse-word   ( <spaces>name -- c-addr u )

Skip leading spaces and parse name delimited by a space. c-addr is the address within the input buffer and u is the length of the selected string. If the parse area is empty, the resulting string has a zero length. (From the Standard)

q@   ( addr -- x )

Fetch a 32 bit quantity from the specified address

q!   ( x addr -- )

Store a 32 bit quantity to the specified address 

w@   ( addr -- x )

Fetch a 16 bit quantity from the specified address

w!   ( x addr -- )

Store a 16 bit quantity to the specified address (the low 16 bits of the given value)

x.   ( x -- )

Pop and display the value in hex format, regardless of the current value of BASE

FiclWin Extras (defined in testmain.c)

break   ( -- )

Does nothing - just a handy place to set a debugger breakpoint

cd      ( "directory-name<newline>" -- )

Executes the Win32 chdir() function, changing the program's logged directory.

clock   ( -- now )

Wrapper for the ANSI C clock() function. Returns the number of clock ticks elapsed since process start.

clocks/sec   ( -- clocks_per_sec )

Pushes the number of ticks in a second as returned by clock

load    ( "filename<newline>" -- )

Opens the Forth source file specified and loads it one line at a time, like INCLUDED (FILE)

pwd     ( -- )

Prints the current working directory as set by cd

system  ( "command<newline>" -- )

Issues a command to a shell; implemented with the Win32 system() call.

spewhash   ( "filename<newline>" -- )

Dumps all threads of the current compilation wordlist to the specified text file. This was useful when I thought there might be some point in attempting to optimize the hash function. I no longer harbor those illusions.

FiclWin Exclusives (no source provided)

!oreg   ( c -- )

Set the value of the simulated LED register as specified (0..255)

@ireg   ( -- c )

Gets the value of the simulated switch block (0..255)

!dac    ( c -- )

Sets the value of the bargraph control as specified. Valid values range from 0..255

@adc    ( -- c )

Fetches the current position of the slider control. Range is 0..255

status"   ( "ccc<quote>" -- )

Set the mainframe window's status line to the text specified, up to the first trailing quote character.

ms   ( u -- )

Causes the running virtual machine to sleep() for the number of milliseconds specified by the top-of-stack value.

Implementation-defined Options

• aligned address requirements (3.1.3.3 Addresses); 

System dependent. You can change the default address alignment by defining FICL_ALIGN on your compiler's command line. The default value is set to 2 in sysdep.h. This causes dictionary entries and ALIGN and ALIGNED to align on 4 byte boundaries. To align on 2ⁿ byte boundaries, set FICL_ALIGN to n. 
• behavior of 6.1.1320 EMIT for non-graphic characters; 

Depends on target system, C runtime library, and your implementation of ficlTextOut().
• character editing of 6.1.0695 ACCEPT and 6.2.1390 EXPECT; 

None implemented in the versions supplied in words.c. Because ficlExec() is supplied a text buffer externally, it's up to your system to define how that buffer will be obtained.
• character set (3.1.2 Character types, 6.1.1320 EMIT, 6.1.1750 KEY); 

Depends on target system and implementation of ficlTextOut()
• character-aligned address requirements (3.1.3.3 Addresses); 

Ficl characters are one byte each. There are no alignment requirements.
• character-set-extensions matching characteristics (3.4.2 Finding definition names); 

No special processing is performed on characters beyond case-folding. Therefore, extended characters will not match their unaccented counterparts.
• conditions under which control characters match a space delimiter (3.4.1.1 Delimiters); 

Ficl uses the Standard C function isspace() to distinguish space characters. The rest is up to your library vendor.
• format of the control-flow stack (3.2.3.2 Control-flow stack); 

Uses the data stack
• conversion of digits larger than thirty-five (3.2.1.2 Digit conversion); 

The maximum supported value of BASE is 36. Ficl will assertion fail in function ltoa of vm.c if the base is found to be larger than 36 or smaller than 2. There will be no effect if NDEBUG is defined, however, other than possibly unexpected behavior. 
• display after input terminates in 6.1.0695 ACCEPT and 6.2.1390 EXPECT; 

Target system dependent
• exception abort sequence (as in 6.1.0680 ABORT"); 

Does ABORT
• input line terminator (3.2.4.1 User input device); 

Target system dependent (implementation of outer loop that calls ficlExec)
• maximum size of a counted string, in characters (3.1.3.4 Counted strings, 6.1.2450 WORD); 

255
• maximum size of a parsed string (3.4.1 Parsing); 

Limited by available memory and the maximum unsigned value that can fit in a CELL (2³²-1). 
• maximum size of a definition name, in characters (3.3.1.2 Definition names); 

Ficl stores the first 31 characters of a definition name.
• maximum string length for 6.1.1345 ENVIRONMENT?, in characters; 

Same as maximum definition name length
• method of selecting 3.2.4.1 User input device; 

None supported. This is up to the target system 
• method of selecting 3.2.4.2 User output device; 

None supported. This is up to the target system 
• methods of dictionary compilation (3.3 The Forth dictionary); 
• number of bits in one address unit (3.1.3.3 Addresses); 

Target system dependent. Ficl generally supports processors that can address 8 bit quantities, but there is no dependency that I'm aware of.
• number representation and arithmetic (3.2.1.1 Internal number representation); 

System dependent. Ficl represents a CELL internally as a union that can hold INT32 (a signed 32 bit scalar value), UNS32 (32 bits unsigned), and an untyped pointer. No specific byte ordering is assumed. 
• ranges for n, +n, u, d, +d, and ud (3.1.3 Single-cell types, 3.1.4 Cell-pair types); 

Assuming a 32 bit implementation, range for signed single-cell values is -2³¹..2³¹-1. Range for unsigned single cell values is 0..2³²-1. Range for signed double-cell values is -2⁶³..2⁶³-1. Range for unsigned single cell values is 0..2⁶⁴-1. 
• read-only data-space regions (3.3.3 Data space);

None 
• size of buffer at 6.1.2450 WORD (3.3.3.6 Other transient regions); 

Default is 255. Depends on the setting of nPAD in ficl.h. 
• size of one cell in address units (3.1.3 Single-cell types); 

System dependent, generally four.
• size of one character in address units (3.1.2 Character types); 

System dependent, generally one.
• size of the keyboard terminal input buffer (3.3.3.5 Input buffers); 

This buffer is supplied by the host program. Ficl imposes no practical limit.
• size of the pictured numeric output string buffer (3.3.3.6 Other transient regions); 

Default is 255 characters. Depends on the setting of nPAD in ficl.h. 
• size of the scratch area whose address is returned by 6.2.2000 PAD (3.3.3.6 Other transient regions); 

Not presently supported 
• system case-sensitivity characteristics (3.4.2 Finding definition names); 

Ficl is not case sensitive
• system prompt (3.4 The Forth text interpreter, 6.1.2050 QUIT); 

"ok>"
• type of division rounding (3.2.2.1 Integer division, 6.1.0100 */, 6.1.0110 */MOD, 6.1.0230 /, 6.1.0240 /MOD, 6.1.1890 MOD); 

Symmetric
• values of 6.1.2250 STATE when true; 

One (no others)
• values returned after arithmetic overflow (3.2.2.2 Other integer operations); 

System dependent. Ficl makes no special checks for overflow. 
• whether the current definition can be found after 6.1.1250 DOES> (6.1.0450 :). 

No. Definitions are unsmudged after ; only, and only then if no control structure matching problems have been detected.

Ambiguous Conditions

The following general ambiguous conditions could occur because of a combination of factors: 

• a name is neither a valid definition name nor a valid number during text interpretation (3.4 The Forth text interpreter); 

Ficl does ABORT and prints the name followed by " not found".
• a definition name exceeded the maximum length allowed (3.3.1.2 Definition names); 

Ficl stores the first 31 characters of the definition name, and uses all characters of the name in computing its hash code. The actual length of the name, up to 255 characters, is stored in the definition's length field.
• addressing a region not listed in 3.3.3 Data Space; 

No problem: all addresses in ficl are absolute. You can reach any 32 bit address in Ficl's address space.
• argument type incompatible with specified input parameter, e.g., passing a flag to a word expecting an n (3.1 Data types); 

Ficl makes no check for argument type compatibility. Effects of a mismatch vary widely depending on the specific problem and operands.
• attempting to obtain the execution token, (e.g., with 6.1.0070 ', 6.1.1550 FIND, etc.) of a definition with undefined interpretation semantics; 

Ficl returns a valid token, but the result of executing that token while interpreting may be undesirable.
• dividing by zero (6.1.0100 */, 6.1.0110 */MOD, 6.1.0230 /, 6.1.0240 /MOD, 6.1.1561 FM/MOD, 6.1.1890 MOD, 6.1.2214 SM/REM, 6.1.2370 UM/MOD, 8.6.1.1820 M*/);

Results are target procesor dependent. Generally, Ficl makes no check for divide-by-zero. The target processor will probably throw an exception.
• insufficient data-stack space or return-stack space (stack overflow); 

With FICL_ROBUST (sysdep.h) set >= 2, most parameter stack operations are checked for underflow and overflow. Ficl does not check the return stack.
• insufficient space for loop-control parameters; 

No check - Evil results.
• insufficient space in the dictionary; 

Ficl generates an error message if the dictionary is too full to create a definition header. It checks ALLOT as well, but it is possible to make an unchecked allocation request that overflows the dictionary.
• interpreting a word with undefined interpretation semantics; 

Ficl protects all ANS Forth words with undefined interpretation semantics from being executed while in interpret state. It is possible to defeat this protection using ' (tick) and EXECUTE, though.
• modifying the contents of the input buffer or a string literal (3.3.3.4 Text-literal regions, 3.3.3.5 Input buffers); 

Varies depending on the nature of the buffer. The input buffer is supplied by ficl's host function, and may reside in read-only memory. If so, writing the input buffer can ganerate an exception. String literals are stored in the dictionary, and are writable.
• overflow of a pictured numeric output string;

In the unlikely event you are able to construct a pictured numeric string of more than 255 characters, the system will be corrupted unpredictably. The buffer area that holds pictured numeric output is at the end of the virtual machine. Whatever is mapped after the offending VM in memory will be trashed, along with the heap structures that contain it. 
• parsed string overflow;

Ficl does not copy parsed strings unless asked to. Ordinarily, a string parsed from the input buffer during normal interpretation is left in-place, so there is no possibility of overflow. If you ask to parse a string into the dictionary, as in SLITERAL, you need to have enough room for the string, otherwise bad things may happen. This is not usually a problem. 
• producing a result out of range, e.g., multiplication (using *) results in a value too big to be represented by a single-cell integer (6.1.0090 *, 6.1.0100 */, 6.1.0110 */MOD, 6.1.0570 >NUMBER, 6.1.1561 FM/MOD, 6.1.2214 SM/REM, 6.1.2370 UM/MOD, 6.2.0970 CONVERT, 8.6.1.1820 M*/); 

Value will be truncated
• reading from an empty data stack or return stack (stack underflow); 

Most stack underflows are detected and prevented if FICL_ROBUST (sysdep.h) is set to 2 or greater. Otherwise, the stack pointer and size are likely to be trashed.
• unexpected end of input buffer, resulting in an attempt to use a zero-length string as a name; 

Ficl returns for a new input buffer until a non-empty one is supplied.

• >IN greater than size of input buffer (3.4.1 Parsing)

Bad Things occur - unpredictable bacause the input buffer is supplied by the host program's outer loop. 
• 6.1.2120 RECURSE appears after 6.1.1250 DOES>

It finds the address of the definition before DOES>
• argument input source different than current input source for 6.2.2148 RESTORE-INPUT

Not implemented 
• data space containing definitions is de-allocated (3.3.3.2 Contiguous regions)

This is OK until the cells are overwritten with something else. The dictionary maintains a hash table, and the table must be updated in order to de-allocate words without corruption. 
• data space read/write with incorrect alignment (3.3.3.1 Address alignment)

Target processor dependent. Consequences include: none (Intel), address error exception (68K). 
• data-space pointer not properly aligned (6.1.0150 ,, 6.1.0860 C,)

See above on data space read/write alignment 
• less than u+2 stack items (6.2.2030 PICK, 6.2.2150 ROLL)

Ficl detects a stack underflow and reports it, executing ABORT, as long as FICL_ROBUST is two or larger. 
• loop-control parameters not available ( 6.1.0140 +LOOP, 6.1.1680 I, 6.1.1730 J, 6.1.1760 LEAVE, 6.1.1800 LOOP, 6.1.2380 UNLOOP)

Loop initiation words are responsible for checking the stack and guaranteeing that the control parameters are pushed. Any underflows will be detected early if FICL_ROBUST is set to two or greater. Note however that Ficl only checks for return stack underflows at the end of each line of text. 
• most recent definition does not have a name (6.1.1710 IMMEDIATE)

No problem. 
• name not defined by 6.2.2405 VALUE used by 6.2.2295 TO

Ficl's version of TO works correctly with VALUEs, CONSTANTs and VARIABLEs. 
• name not found (6.1.0070 ', 6.1.2033 POSTPONE, 6.1.2510 ['], 6.2.2530 [COMPILE])

Ficl prints an error message and does ABORT
• parameters are not of the same type (6.1.1240 DO, 6.2.0620 ?DO, 6.2.2440 WITHIN)

No check. Results vary depending on the specific problem. 
• 6.1.2033 POSTPONE or 6.2.2530 [COMPILE] applied to 6.2.2295 TO

The word is postponed correctly. 
• string longer than a counted string returned by 6.1.2450 WORD

Ficl stores the first FICL_STRING_MAX-1 chars in the destination buffer. (The extra character is the trailing space required by the standard. Yuck.) 
• u greater than or equal to the number of bits in a cell (6.1.1805 LSHIFT, 6.1.2162 RSHIFT)

Depends on target process or and C runtime library implementations of the << and >> operators on unsigned values. For I386, the processor appears to shift modulo the number of bits in a cell. 
• word not defined via 6.1.1000 CREATE (6.1.0550 >BODY, 6.1.1250 DOES>)

words improperly used outside 6.1.0490 <# and 6.1.0040 #> (6.1.0030 #, 6.1.0050 #S, 6.1.1670 HOLD, 6.1.2210 SIGN)
Don't. CREATE reserves a field in words it builds for DOES>to fill in. If you use DOES> on a word not made by CREATE, it will overwrite the first cell of its parameter area. That's probably not what you want. Likewise, pictured numeric words assume that there is a string under construction in the VM's scratch buffer. If that's not the case, results may be unpleasant.

Locals Implementation-defined options

• maximum number of locals in a definition (13.3.3 Processing locals, 13.6.2.1795 LOCALS|)

Default is 16. Change by redefining FICL_MAX_LOCALS, defined in sysdep.h

Locals Ambiguous conditions

• executing a named local while in interpretation state (13.6.1.0086 (LOCAL))

Locals can be found in interpretation state while in the context of a definition under construction. Under these circumstances, locals behave correctly. Locals are not visible at all outside the scope of a definition. 
• name not defined by VALUE or LOCAL (13.6.1.2295 TO)

See the CORE ambiguous conditions, above (no change)

Programming Tools Implementation-defined options

• source and format of display by 15.6.1.2194 SEE

SEE de-compiles definitions from the dictionary. Because Ficl words are threaded by their header addresses, it is very straightforward to print the name and other characteristics of words in a definition. Primitives are so noted. Colon definitions are decompiled, but branch target labels are not reconstructed. Literals and string literals are so noted, and their contents displayed.

Search Order Implementation-defined options

• maximum number of word lists in the search order (16.3.3 Finding definition names, 16.6.1.2197 SET-ORDER) 

Defaults to 16. Can be changed by redefining FICL_DEFAULT_VOCS, declared in sysdep.h 
• minimum search order (16.6.1.2197 SET-ORDER, 16.6.2.1965 ONLY) 

Equivalent to FORTH-WORDLIST 1 SET-ORDER

Search Order Ambiguous conditions

• changing the compilation word list (16.3.3 Finding definition names)

Ficl stores a link to the current definition independently of the compile wordlist while it is being defined, and links it into the compile wordlist only after the definition completes successfully. Changing the compile wordlist mid-definition will cause the definition to link into the new compile wordlist. 
• search order empty (16.6.2.2037 PREVIOUS)

Ficl prints an error message if the search order underflows, and resets the order to its default state. 
• too many word lists in search order (16.6.2.0715 ALSO)

Ficl prints an error message if the search order overflows, and resets the order to its default state.