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ANS required documentation

Provided word sets

To the best of knowledge FLK is an

ANS Forth System

providing the Core Extensions word set
providing the Double-Number word set
providing the Double-Number Extensions word set
providing the Exception word set
providing the Exception Extensions word set
providing the Facility word set
providing the Facility Extensions word set
providing the File Access word set
providing the File Access Extensions word set
providing the Floating-Point word set
providing the Floating-Point Extensions word set
providing the Memory-Allocation word set
providing the Memory-Allocation Extensions
providing the Programming-Tools word set
providing the Programming-Tools Extensions word set
providing the Search-Order word set
providing the Search-Order Extensions word set
providing the String word set
providing the String Extensions word set

Implementation defined values

aligned address requirements (3.1.3.3 Addresses): Since FLK is tailored to the Intel 386+ CPU's running Linux, neither the cell aligned addresses nor the character aligned addresses have to be aligned. It is recommended for speed to align cells to addresses that are multiples of four.
behavior of 6.1.1320 EMIT for non-graphic characters: EMIT passes its argument directly to the terminal, so its behavior is dependend upon the behavior of the terminal and the used character set.
character editing of 6.1.0695 ACCEPT and 6.2.1390 EXPECT: If the used terminal supports them the keys cursor left, cursor right, back space, delete character, cursor home, cursor end, return, set tabulator, cursor up and cursor down are accepted.
character set (3.1.2 Character types, 6.1.1320 EMIT, 6.1.1750 KEY): The character set used by EMIT is terminal depended. The characters returned by KEY are limitied to the range of decimal 32...127 inclusive.
character-aligned address requirements (3.1.3.3 Addresses): No restriction. Any address is character aligned.
character-set-extensions matching characteristics (3.4.2 Finding definition names): Word names are copied to the dictionary as found (case sensitive behaviour) although find names can be case sensitive or insensitive.
conditions under which control characters match a space delimiter (3.4.1.1 Delimiters): PARSE and all other words that parse accept characters below or equal to 32 as delimiters.
format of the control-flow stack (3.2.3.2 Control-flow stack): The control flow stack is implemented using the data stack.
conversion of digits larger than thirty-five (3.2.1.2 Digit conversion): A number may contain upper of lower case letters. If they exceed the range of digits, the conversion is ended without error. If the number is converted by the interpreter, the whole word is considered unknown.
display after input terminates in 6.1.0695 ACCEPT and 6.2.1390 EXPECT: The cursor is placed to the right of the last character.
exception abort sequence (as in 6.1.0680 ABORT"): Address and length of the string is transfered to special variables and the exception -2 is raised.
input line terminator (3.2.4.1 User input device): The character '\n' as defined by the C compiler. Its numerical value is 10 decimal.
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): 255
maximum size of a definition name, in characters (3.3.1.2 Definition names): 255
maximum string length for 6.1.1345 ENVIRONMENT?, in characters: unlimited
method of selecting 3.2.4.1 User input device: The user input device is the standard input of the program.
method of selecting 3.2.4.2 User output device: The user output device is the standard output of the program.
methods of dictionary compilation (3.3 The Forth dictionary): The name space is distributed over the code space since the headers are in code space and the names are part of the header. It is possible to access the code space by @ etc. An execution token is the address of the first byte of a header.
number of bits in one address unit (3.1.3.3 Addresses): 8
number representation and arithmetic (3.2.1.1 Internal number representation): little endian, two's complement
ranges for n, +n, u, d, +d, and ud (3.1.3 Single-cell types, 3.1.4 Cell-pair types): The following ranges are inclusive the given borders: n -2147483648 2147483647 +n 0 2147483647 u 0 4294967295 d -9223372036854775808 9223372036854775807 +d 0 9223372036854775807 ud 0 18446744073709551615
read-only data-space regions (3.3.3 Data space): The whole data space is writable although is not recommended to bomb around at will.
size of buffer at 6.1.2450 WORD (3.3.3.6 Other transient regions): 256 characters, defined by the meta compiler constant #WORD-PAD
size of one cell in address units (3.1.3 Single-cell types): 4
size of one character in address units (3.1.2 Character types): 1
size of the keyboard terminal input buffer (3.3.3.5 Input buffers): 256 character, defined by the meta compiler constant #TIB
size of the pictured numeric output string buffer (3.3.3.6 Other transient regions): 80 characters, defined by the meta compiler constant ((pnolen))
size of the scratch area whose address is returned by 6.2.2000 PAD (3.3.3.6 Other transient regions): 256 characters, defined by the meta compiler constant #PAD-LEN
system case-sensitivity characteristics (3.4.2 Finding definition names): FLK's case sensitivity is controlled by the variable CAPS. If it contains TRUE FLK is case insensitive, otherwise it is case sensitive.
system prompt (3.4 The Forth text interpreter, 6.1.2050 QUIT): CR ." OK " CR in interpretation state and CR ." ? " in compilation state.
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: TRUE
values returned after arithmetic overflow (3.2.2.2 Other integer operations): wrap-around, (n modulo 2^32, d modulo 2^64)
whether the current definition can be found after 6.1.1250 DOES> (6.1.0450 :): The current definition can not be found after DOES>

Ambiguos conditions

a name is neither a valid definition name nor a valid number during text interpretation (3.4 The Forth text interpreter): Display the unknown word and raise exception -13.
a definition name exceeded the maximum length allowed (3.3.1.2 Definition names): The name is truncated to 255 characters
addressing a region not listed in 3.3.3 Data Space: As long as the address is a valid address in terms of the operating system nothing happens. Otherwise a segmentation fault is raised and handled by the operating system.
argument type incompatible with specified input parameter, e.g., passing a flag to a word expecting an n (3.1 Data types): The parameter is interpreted as if it was of the right type.
attempting to obtain the execution token, (e.g., with 6.1.0070 ', 6.1.1550 FIND, etc.) of a definition with undefined interpretation semantics: The execution tokens of all known words can be obtained.
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*/): The operating system raises a Floating exception.
insufficient data-stack space or return-stack space (stack overflow): Ignored, might cause a segmentation fault.
insufficient space for loop-control parameters: Ignored, might cause a segmentation fault.
insufficient space in the dictionary: Exception -8 is raised.
interpretating a word with undefined interpretation semantics: Exception -14 is raised.
modifying the contents of the input buffer or a string literal (3.3.3.4 Text-literal regions, 3.3.3.5 Input buffers): Ignored.
overflow of a pictured numeric output string: Exception -17 is raised.
parsed string overflow: The parsed string is truncated.
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*/): Wrap around. n modulo 2^32
reading from an empty data stack or return stack (stack underflow): Ignored, might cause a segmentation fault.
unexpected end of input buffer, resulting in an attempt to use a zero-length string as a name: Exception -16 is raised.
>IN greater than size of input buffer (3.4.1 Parsing): Parsing is aborted, an empty string is returned.
6.1.2120 RECURSE appears after 6.1.1250 DOES>: A call to the word beeing defined is compiled.
argument input source different than current input source for 6.2.2148 RESTORE-INPUT: The described input source is restored without a notification sent to the program.
data space containing definitions is de-allocated (3.3.3.2 Contiguous regions): If you are lucky, some words disappear. If not the system crashed at the next FIND or SEARCH-WORDLIST.
data space read/write with incorrect alignment (3.3.3.1 Address alignment): Ignored.
data-space pointer not properly aligned (6.1.0150 ,, 6.1.0860 C,): Ignored.
less than u+2 stack items (6.2.2030 PICK, 6.2.2150 ROLL): The system crashes with a segmentation fault.
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): The values found on the return stack are interpreted as loop control parameters. The loop might stop, perform another run or the system crashes with a segmentation fault.
most recent definition does not have a name (6.1.1710 IMMEDIATE): The immediate flag is set in the header anyway. Nothing else happens.
name not defined by 6.2.2405 VALUE used by 6.2.2295 TO: As long as name is created by CREATE the value is stored. You are responsible that there was room for one cell. If name is not CREATEd or a VALUE, exception -31 is raised.
name not found (6.1.0070 ', 6.1.2033 POSTPONE, 6.1.2510 ['], 6.2.2530 [COMPILE]): Exception -13 is raised.
parameters are not of the same type (6.1.1240 DO, 6.2.0620 ?DO, 6.2.2440 WITHIN): The parameters are interpreted as if they were of the same type.
6.1.2033 POSTPONE or 6.2.2530 [COMPILE] applied to 6.2.2295 TO: The equivalent of ['] TO COMPILE, is performed.
string longer than a counted string returned by 6.1.2450 WORD: The string is handled as if is was shorter than a byte counted string. That's what the address,length notation is for, isn't it?
u greater than or equal to the number of bits in a cell (6.1.1805 LSHIFT, 6.1.2162 RSHIFT): Only the least significant bits of u are used, equivalent to e.g.31 AND LSHIFT.
word not defined via 6.1.1000 CREATE (6.1.0550 >BODY, 6.1.1250 DOES>): Exception -31 is raised.
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): As long as the pictured numeric output buffer does not overflow it is ignored. Otherwise exception -17 is raised.

n	-2147483648	2147483647
+n	0	2147483647
u	0	4294967295
d	-9223372036854775808	9223372036854775807
+d	0	9223372036854775807
ud	0	18446744073709551615

ANS required documentation

Provided word sets

Implementation defined values

Ambiguos conditions

Other system documentation

FLK