N4Asm Namespace Reference

Functions
U8	_find (U8 *tkn, IU *adr)
	search the keyword through colon word linked-list
void	_add_word ()
void	_add_branch (U8 op)
void	_add_str ()
void	_list_voc (U16 n)
void	save (U8 autorun=0)
	persist user dictionary to EEPROM
U16	load (U8 autorun=0)
	restore user dictionary from EEPROM
IU	reset ()
	reset internal pointers (for BYE)
IU	query ()
	dictionary, string list scanners
N4OP	parse (U8 *tkn, IU *rst, U8 run)
	Instruction decoder.
void	compile (IU *rp0)
	Forth compiler.
void	create ()
	meta compiler
void	comma (DU v)
	compile a 16-bit value onto dictionary
void	ccomma (DU v)
	‍compile a 16-bit value onto dictionary
void	does (IU xt)
	‍compile a 16-bit value onto dictionary
void	dot_str ()
void	variable ()
	create a variable on dictionary
void	constant (DU v)
void	words ()
	display words in dictionary
void	forget ()
	forgets word in the dictionary
void	see ()
	decode colon word
IU	trace (IU adr, U8 ir, char delim=0)
	print execution tracing info

Variables
U8 *	last { NULL }
	pointer to last word, for debugging
U8 *	here { NULL }
	top of dictionary (exposed to _vm for HRE, ALO opcodes)
U8	tab = 0

Detailed Description

LFA NFA XT=PFA +----—+----—+-----------------—+ | lnk | name | parameters...I_RET | +----—+----—+-----------------—+ | | | v v v 16-bits 3-bytes variable length parameters

Assembler class

Function Documentation

_find()

U8 N4Asm::_find	(	U8 *	tkn,
		IU *	adr
	)

search the keyword through colon word linked-list

‍find colon word address of next input token

Returns

1 - token found
0 - token not found

• return offset of dic

_add_word()

void N4Asm::_add_word

(

)

‍create name field with link back to previous word

fetch one token from console

create 3-byte name field

_add_branch()

void N4Asm::_add_branch

(

U8

op

)

‍create branching for instructions

‍f IF...THN, f IF...ELS...THN BGN...f UTL, BGN...f WHL...RPT, BGN...f WHL...f UTL n1 n0 FOR...NXT

_add_str()

void N4Asm::_add_str

(

)

‍display the opcode name

_list_voc()

void N4Asm::_list_voc

(

U16

n

)

‍list words in built-in vocabularies

save()

void N4Asm::save

(

U8

autorun

)

persist user dictionary to EEPROM

‍persist dictionary from RAM into EEPROM

verify EEPROM capacity to hold user dictionary

create EEPROM dictionary header

copy user dictionary into EEPROM byte-by-byte

load()

IU N4Asm::load

(

U8

autorun

)

restore user dictionary from EEPROM

‍restore dictionary from EEPROM into RAM

Returns

lnk: autorun address (of last word from EEPROM) LFA_END: no autorun or EEPROM not been setup yet

validate EEPROM contains user dictionary (from previous run)

retrieve metadata (sizes) of user dictionary

retrieve user dictionary byte-by-byte into memory

adjust user dictionary pointers

reset()

IU N4Asm::reset

(

)

reset internal pointers (for BYE)

‍reset internal pointers (called by VM::reset)

Returns

1: autorun last word from EEPROM 0: clean start

query()

IU N4Asm::query

(

)

dictionary, string list scanners

‍get address of next input token

get xt of next input token, 0 if not found

< lfa of word

check if token is in dictionary

• not found, bail

• xt = adr + lnk[2] + name[3]

parse()

N4OP N4Asm::parse	(	U8 *	tkn,
		IU *	rst,
		U8	run
	)

Instruction decoder.

‍parse given token into actionable item

• WRD - is a colon word? [lnk(2),name(3)]

• IMM - is a immediate word?

• PRM - is a primitives?

• NUM - is a number literal?

• ERR - unknown token

Parameters

tkn	token to be parsed
rst	parsed result
run	run mode flag (1: run mode, 0: compile mode)

compile()

void N4Asm::compile

(

IU *

rp0

)

Forth compiler.

‍Forth assembler (creates word onto dictionary)

fetch token, create name field linked to previous word

‍loop til exhaust all tokens (tkn==NULL)

‍trace assembler progress if enabled

‍determine type of operation, and keep opcode in tmp

‍an immediate command?

• add branching opcode

• semi-colon i.e. end of word

• clear token to exit compile mode

‍debug memory dump, if enabled

‍a colon word? [addr + lnk(2) + name(3)]

• call subroutine

‍a built-in primitives?

• add found primitive opcode

• do extra, if it's a ." (dot_string) or S" (do_string) command

‍a literal (number)?

• 1-byte literal, or

• 3-byte literal

‍extended words, not implemented yet

‍then, token type not found

• restore last, here pointers

• reset tib and token parser

• bail, terminate loop!

Parameters

rp0	memory address to be used as assembler return stack

create()

void N4Asm::create

(

)

meta compiler

‍meta compiler

create a word name field

‍create a word header (link + name field)

fetch token, create name field linked to previous word

< address to variable storage

‍1-byte literal

‍or, 3-byte literal

comma()

void N4Asm::comma

(

DU

v

)

compile a 16-bit value onto dictionary

ccomma()

void N4Asm::ccomma

(

DU

v

)

‍compile a 16-bit value onto dictionary

compile a 8-it value onto dictionary

does()

void N4Asm::does

(

IU

xt

)

‍compile a 16-bit value onto dictionary

metaprogrammer (jump to definding word DO> section)

‍metaprogrammer (jump to definding word DO> section)

start walking back

shift down parameters by 2 bytes

adjust the PFA

replace NOP with a JMP,

and a NOP, (not necessary but nice to SEE)

extra 2 bytes due to shift

dot_str()

void N4Asm::dot_str

(

)

< keep current HERE

• fill string on PAD

• print the string

• restore HERE

variable()

void N4Asm::variable

(

)

create a variable on dictionary

‍create a variable on dictionary

• note: 8 or 10-byte per variable

add actual literal storage area

constant()

void N4Asm::constant

(

DU

v

)

‍create a constant on dictionary

• note: 8 or 10-byte per variable

create a constant on dictionary

fetch token, create name field linked to previous word

‍handle 1-byte constant

‍or, constant stored as 3-byte literal

words()

void N4Asm::words

(

)

display words in dictionary

‍display words in dictionary

‍wraping width

from last, loop through dictionary

‍optionally show address

‍show word name

forget()

void N4Asm::forget

(

)

forgets word in the dictionary

‍drop words from the dictionary

< cfa of word

• bail if word not found

word found, rollback here

< pointer to word's link

• reset last word address

• reset current pointer

see()

void N4Asm::see

(

)

decode colon word

‍decode colon word

< cfa of word

• not found in colon words

word found, walk parameter field

< pointer to word's name

trace()

U16 N4Asm::trace	(	IU	a,
		U8	ir,
		char	delim
	)

print execution tracing info

‍execution tracer (debugger, can be modified into single-stepper)

‍is a jump instruction?

‍is a primitive?

‍and a number (i.e. 1-byte literal)

Parameters

adr	address to word to be executed
ir	instruction register value
delim	token delimiter

Variable Documentation

last

U8 * N4Asm::last { NULL }

pointer to last word, for debugging

here

U8 * N4Asm::here { NULL }

top of dictionary (exposed to _vm for HRE, ALO opcodes)

tab

U8 N4Asm::tab = 0

tracing indentation counter