A2osX/BIN/FORTH.S.txt

NEW
  AUTO 3,1
				.LIST OFF
				.OP	65C02
				.OR	$2000
				.TF bin/forth
*--------------------------------------
				.INB inc/macros.i
				.INB inc/a2osx.i
				.INB inc/mli.i
				.INB inc/mli.e.i
*--------------------------------------
CODE.SIZE		.EQ 2048
DATA.SIZE		.EQ 2048
INPUT.SIZE		.EQ 256
OUTPUT.SIZE		.EQ 256
CL.SIZE			.EQ 256
*--------------------------------------
SYM.T.CONST		.EQ 0
SYM.T.VAR		.EQ 64
SYM.T.CODE		.EQ 128
*--------------------------------------
				.DUMMY
				.OR ZPBIN
ZS.START
ZPCodePtr		.BS 2
ZPDataPtr		.BS 2
ZPInputPtr		.BS 2
ZPOutputPtr		.BS 2

ZPKeyID			.BS 2
ZPType			.BS 1
				.BS 1
ZPAddrPtr		.BS 2

ZPPtr1			.BS 2
ZPPtr2			.BS 2
ZPPtr3			.BS 2

ZPCLBuf			.BS 2
ZPCLBufPtr		.BS 2

CL.Ptr			.BS 1
CL.Len			.BS 1
CL.bReady		.BS 1
CL.bEscMode		.BS 1
CL.MaxCnt		.BS 1

ArgIndex		.EQ *
bCompile		.BS 1
RP				.BS 1

ZS.END			.ED
*--------------------------------------
*			File Header (16 Bytes)
*--------------------------------------
CS.START		cld
				jmp (.1,x)
				.DA #$61				6502,Level 1 (65c02)
				.DA #1					BIN Layout Version 1
				.DA #0					S.PS.F.EVENT
				.DA #0
				.DA CS.END-CS.START		Code Size (without Constants)
				.DA DS.END-DS.START		Data SegmentSize
				.DA #256				Stack Size
				.DA #ZS.END-ZS.START	Zero Page Size
				.DA 0
*--------------------------------------
* Relocation Table
*--------------------------------------
.1				.DA CS.INIT
				.DA CS.RUN
				.DA CS.DOEVENT
				.DA	CS.QUIT
L.MSG.GREETINGS	.DA MSG.GREETINGS
L.MSG.USAGE		.DA MSG.USAGE
L.MSG.ECHOCRLF	.DA MSG.ECHOCRLF
L.MSG.DEBUG		.DA MSG.DEBUG
L.MSG.ERR		.DA MSG.ERR
L.MSG.PROMPT	.DA MSG.PROMPT
L.MSG.PROMPTCRLF	.DA MSG.PROMPTCRLF
L.FMT.Byte		.DA FMT.Byte
L.FMT.int16		.DA FMT.int16
J.ESC			.DA CL.BS			left arrow
				.DA CL.DN
				.DA CL.UP
*				.DA HIS.GetNext			
*				.DA HIS.GetPrev
				.DA CL.NAK			right arrow
L.KEYWORDS		.DA KEYWORDS
J.KEYWORDS		.DA KW.DUP
				.DA KW.DROP
				.DA KW.SWAP
				.DA KW.OVER
				.DA KW.ROT
				.DA KW.mDUP
				.DA KW.gR
				.DA KW.Rg
				.DA KW.R
				.DA KW.Add
				.DA KW.DAdd
				.DA KW.Sub
				.DA KW.Mul
				.DA KW.Div
				.DA KW.Mod
				.DA KW.DivMod
				.DA KW.MulDivMod
				.DA KW.MulDiv
				.DA KW.MAX
				.DA KW.MIN
				.DA KW.ABS
				.DA KW.DABS
				.DA KW.MINUS
				.DA KW.DMINUS
				.DA KW.AND
				.DA KW.OR
				.DA KW.XOR
				.DA KW.LWR
				.DA KW.GTR
				.DA KW.EQ
				.DA KW.NEGATIVE
				.DA KW.ZERO
				.DA KW..
				.DA KW..R
				.DA KW.D.
				.DA KW.D.R
				.DA KW.CR
				.DA KW.SPACE
				.DA KW.SPACES
				.DA KW.PRINT
				.DA KW.DUMP
				.DA KW.TYPE
				.DA KW.COUNT
				.DA KW.TERMINAL
				.DA KW.KEY
				.DA KW.EMIT
				.DA KW.EXPECT
				.DA KW.WORD
				.DA KW.NUMBER
				.DA KW.STARTSTR
				.DA KW.STRADD
				.DA KW.STRDBL
				.DA KW.SIGN
				.DA KW.ENDSTR
				.DA KW.HOLD
				.DA KW.DECIMAL
				.DA KW.HEX
				.DA KW.OCTAL
				.DA KW.FETCHW
				.DA KW.STOREW
				.DA KW.FETCHB
				.DA KW.STOREB
				.DA KW.FETCHPRINTW
				.DA KW.ADDTOW
				.DA KW.CMOVE
				.DA KW.FILL
				.DA KW.ERASE
				.DA KW.BLANKS
				.DA KW.HERE
				.DA KW.PAD
				.DA KW.ALLOT
				.DA KW.nCOMPILE
				.DA KW.QUOTE
				.DA KW.FORGET
				.DA KW.DEFINITIONS
				.DA KW.VOCABULARY
				.DA KW.FORTH
				.DA KW.EDITOR
				.DA KW.ASSEMBLER
				.DA KW.VLIST
				.DA KW.BCOLON
				.DA KW.ECOLON
				.DA KW.VARIABLE
				.DA KW.CONSTANT
				.DA KW.ACODE
				.DA KW.FCODE
				.DA KW.DO
				.DA KW.LOOP
				.DA PW.pLOOP
				.DA KW.I
				.DA KW.LEAVE
				.DA KW.IF
				.DA KW.ELSE
				.DA KW.ENDIF
				.DA KW.BEGIN
				.DA KW.UNTIL
				.DA KW.REPEAT
				.DA KW.WHILE
				.DA KW.COMMENT
				.DA 0
*--------------------------------------
CS.INIT			clc
CS.INIT.RTS		rts
*--------------------------------------
CS.RUN			>PUSHW L.MSG.GREETINGS
				>PUSHW A2osX.KVER
				>PUSHBI 2
				>SYSCALL PrintF
				bcs CS.INIT.RTS

				jsr CS.RUN.ARGS
				bcs CS.INIT.RTS
				
				>LDYAI CODE.SIZE
				>SYSCALL GetMem
				bcs CS.INIT.RTS

				>STYA ZPCodePtr
				>STYA.G CodeBuf
				txa
				>STA.G hCodeBuf
				
				>LDYAI DATA.SIZE
				>SYSCALL GetMem
.9				bcs CS.INIT.RTS

				>STYA ZPDataPtr
				>STYA.G DataBuf
				txa
				>STA.G hDataBuf

				>LDYAI INPUT.SIZE
				>SYSCALL GetMem
				bcs .9

				>STYA.G InputBuf
				txa
				>STA.G hInputBuf

				>LDYAI OUTPUT.SIZE
				>SYSCALL GetMem
				bcs .9

				>STYA.G OutputBuf
				txa
				>STA.G hOutputBuf

				>LDYAI CL.SIZE
				>SYSCALL GetMem
				bcs .9

				>STYA ZPCLBuf
				txa
				>STA.G hCLBuf
				
				>SYSCALL SListNew
				bcs .9
				
				>STA.G hSList
				
				stz bCompile
				lda #127
				sta RP

CS.RUN.LOOP		>SLEEP

				>LDA.G bDebug
				bpl .2

				jsr PrintDebugMsg

.2				>LDA.G bTrace
				bpl .3

				>LDYA ZPCLBuf
				jsr PrintTraceMsg

.3				jsr CS.FORTH.Run
				bcc CS.RUN.LOOP

				cmp #MLI.E.EOF
				beq .8
				
				cmp #3
				beq .99

				pha
				>LDA.G bExitOnEOF
				bmi .9
				
				pla
				>PUSHA
				>PUSHW ZPCLBuf
				>SYSCALL GetErrorMessage
				>LDYA ZPCLBuf
				>SYSCALL PutS
				bra CS.RUN.LOOP
				
*				jsr PrintErrMsg

.9				pla
.99				sec
				rts

.8				lda #0					Exit Code = Success
				sec
				rts
*--------------------------------------
CS.RUN.ARGS		inc ArgIndex	

				lda ArgIndex
				>SYSCALL ArgV
				bcs .8
		
				>STYA ZPPtr1
				lda (ZPPtr1)
				cmp #'-'
				bne .4

				ldy #1
				lda (ZPPtr1),y

				ldx #OptionVars-OptionList-1

.1				cmp OptionList,x
				beq .2

				dex
				bpl .1

				bra .90

.2				ldy OptionVars,x
				lda #$ff
				sta (pData),y
				bra CS.RUN.ARGS

.4				>LDA.G hFile
				bne .90

				>LDYA ZPPtr1
				jsr CS.RUN.FOpen
				bcs .9

				>STA.G hFile
				bra CS.RUN.ARGS

.8				clc
.9				rts

.90				>PUSHW L.MSG.USAGE
				>PUSHBI 0
				>SYSCALL PrintF

				lda #E.SYN
				sec						QUIT Process
				rts
*--------------------------------------
CS.FORTH.Run	jsr CL.Reset

				>LDA.G hFile
				bne CS.FORTH.Run.File

				lda #80
				sta CL.MaxCnt

				jsr PrintPrompt
				bcs .9
				
.1				>SYSCALL GetChar
				bcs .9					I/O error 

.2				cmp #3					Ctrl-C
				beq .9					CS

				jsr CL.CHARIN

				bit CL.bReady			Something to execute ?
				bpl .1				
				
				>PUSHW L.MSG.PROMPTCRLF
				>PUSHBI 0
				>SYSCALL PrintF

				jmp CS.RUN.EXEC
				
.9				rts				
*--------------------------------------
CS.FORTH.Run.File
				>PUSHWI 256
				>PUSHW ZPCLBuf

				>LDA.G hFile
				>SYSCALL fgets
				bcs .9

				lda (ZPCLBuf)
				beq .8
				
				cmp #'#'
				bne .1
				
				ldy #1
				lda (ZPCLBuf),y
				beq .1
				
				cmp #'!'
				beq .8
				
.1				jmp CS.RUN.EXEC

.8				clc
.9				rts
*--------------------------------------
CS.RUN.EXEC		lda (ZPCLBufPtr)
				beq .8

.1				jsr KW.Lookup
				bcs .2

				tya
				jsr NextKW

				jsr .7
				bcc CS.RUN.EXEC

				rts

.2				jsr CS.RUN.GetSymbol
				bcs .5
				
				bit ZPType
				bmi .4
				
				bvc .3
				
				>PUSHW ZPAddrPtr
				
				rts
				
.3				ldy #1
				>PUSHB (ZPAddrPtr),y
				>PUSHB (ZPAddrPtr)
				rts
				
.4				bit bCompile
				bmi .40
				
				jsr .80
				bcc CS.RUN.EXEC
				
				rts
				
.40				>LDYA ZPAddrPtr
				jsr EmitJsrYA		
				bra CS.RUN.EXEC
				
.5				jsr CS.RUN.GetNum
				bcs .9

.6				jsr NextChar			Skip SPACE if any
				bne .1
				
.8				clc
.9				rts
				
.7				txa
				asl
				tax
	
				cpx #$A2				; ECOLON always EXECUTE
				beq .71

 				bit bCompile
				bmi .72
				
.70				bcs .99					cannot exec compil only

.71				jmp (J.KEYWORDS,x)

.72				jmp CP.RUN

.80				jmp (ZPAddrPtr)

.99				lda #E.SYN
				sec
				rts
*--------------------------------------
CS.RUN.FOpen	>PUSHYA
				>PUSHBI	O.RDONLY
				>PUSHBI S.FI.T.TXT
				>PUSHWZ					Aux type
				>SYSCALL FOpen
				bcs .9

				>STA.G hFile
				
.9				rts
*--------------------------------------
CS.RUN.GetSymbol
				>PUSHB.G hSList
				>PUSHW ZPCLBufPtr
				>SYSCALL SListLookup
				bcs .9
				
				>STYA ZPKeyID
	
				txa
				jsr NextKW
				
				>PUSHB.G hSList
				>PUSHW ZPKeyID
				>PUSHWI ZPType
				>PUSHWI 4				4 bytes
				>PUSHWZ					From Start
				
				>SYSCALL SListGetData
				bcs .9
				
				
				
				
				
				
				
.9				rts
*--------------------------------------
CS.RUN.GetNum	>PUSHW ZPCLBufPtr
				>PUSHWI ZPCLBufPtr
				>PUSHBI 10
				>SYSCALL StrToL
				bcs .9
				
				ldy #2
				lda (pStack)
				sta (pStack),y
				
				inc pStack
				
				lda (pStack)
				sta (pStack),y
				
				inc pStack

				bit bCompile
				bpl .9

.1				>PULLA
				jsr EmitPushA
				>PULLA
				jmp EmitPushA

.9				rts
*--------------------------------------
CS.DOEVENT		sec
				rts
*--------------------------------------
CS.QUIT			>LDA.G hSList
				beq .1

				>PUSHA
				>SYSCALL SListFree

.1				>LDA.G hFile
				beq .2
				
				>SYSCALL FClose

.2				ldy #hCodeBuf
				jsr .7
				
				ldy #hDataBuf
				jsr .7
				
				ldy #hInputBuf
				jsr .7

				ldy #hOutputBuf
				jsr .7

				ldy #hCLBuf

.7				lda (pData),y
				beq .8
				
				>SYSCALL FreeMem
				
.8				clc
				rts
*--------------------------------------
PrintPrompt		>PUSHW L.MSG.PROMPT
				>PUSHBI 0
				>SYSCALL PrintF
				rts
*--------------------------------------
PrintErrMsg		>LDYA.G ZPCLBuf
				>STYA ZPPtr1

				clc

				rts
*--------------------------------------
PrintDebugMsg
				clc
				rts
*--------------------------------------
PrintTraceMsg	>STYA ZPPtr3

PrintTraceMsg.3	>PUSHBI '>'
				ldy #S.PS.hStdErr
				lda (pPS),y
				>SYSCALL FPutC
				
				ldy #$ff

.1				iny
				lda (ZPPtr3),y
				beq .8
				
				cmp #C.CR
				beq .8
				
				phy
				>PUSHA
				ldy #S.PS.hStdErr
				lda (pPS),y
				>SYSCALL FPutC
				ply
				bra .1
				
.8 				ldy #S.PS.hStdErr
				lda (pPS),y
				>PUSHA
				
				>PUSHW L.MSG.ECHOCRLF
				>PUSHBI 0
				>SYSCALL FPrintF

				rts
*--------------------------------------
CheckLFAfterCR	ldy #S.PS.hStdIn		Check for any extra LF
				lda (pPS),y
				>SYSCALL FEOF
				bcs .9
				
				tay
				bne .9
				>SYSCALL GetChar
				
.9				rts
*--------------------------------------
IncPtr1			inc ZPPtr1
				bne IncPtr1.8
				inc ZPPtr1+1
IncPtr1.8		rts
*--------------------------------------
NextKW			clc
				adc ZPCLBufPtr
				sta ZPCLBufPtr
				bcc NextCharNB
				inc ZPCLBufPtr+1
*--------------------------------------
NextCharNB		lda (ZPCLBufPtr)
				beq .8
				
				jsr IsSpaceOrCR
				bcs .8

				inc ZPCLBufPtr
				bne NextCharNB
				inc ZPCLBufPtr+1
				bra NextCharNB

.8				rts			
*--------------------------------------
NextChar		lda (ZPCLBufPtr)
				beq .8
				
				inc ZPCLBufPtr
				bne .8
				
				inc ZPCLBufPtr+1
				
.8				rts
*--------------------------------------
ToUpperCase		cmp #'a'
				bcc .8

				cmp #'z'+1
				bcs .8

				eor #$20

.8				clc						exit CC to allow Jmp to
				rts
*--------------------------------------
IsSpaceOrCR		cmp #C.SPACE
				beq IsEndKW.8

				cmp #C.CR
				beq IsEndKW.8

				sec
				rts

IsEndKW.8		clc
				rts
*--------------------------------------
CheckStackPop4	lda pStack
				sec
				sbc #4
				bcc .9

				clc
				rts

.9				lda #E.STACKERROR
				sec
				rts
*--------------------------------------
EmitPullA		lda #$B2				lda (zp)
				jsr EmitByte
				
				lda #pStack
				jsr EmitByte
				
				lda #$E6				inc zp

				lda #pStack
				bra EmitByte
*--------------------------------------
EmitPushA		pha
				lda #$A9				LDA imm
				jsr EmitByte
				
				pla
				jsr EmitByte
				
				lda #$C6				DEC zp
				jsr EmitByte
				
				lda #pStack
				jsr EmitByte

				lda #$92				STA (zp)
				jsr EmitByte
				
				lda #pStack
				bra EmitByte
*--------------------------------------
EmitJsrYA		pha
				lda #$20
				jsr EmitByte
				tya
				jsr EmitByte
				pla
*--------------------------------------
EmitByte		sta (ZPCodePtr)
				inc ZPCodePtr
				bne .8
				inc ZPCodePtr+1
.8				rts				
*--------------------------------------
				.INB usr/src/bin/forth.s.cl
				.INB usr/src/bin/forth.s.cp
				.INB usr/src/bin/forth.s.kw
*--------------------------------------
CS.END
*--------------------------------------
MSG.GREETINGS	.AZ "\r\nA2osX-FORTH %d.%d (figForth)\r\n\r\n"
MSG.USAGE		.AS "Usage : FORTH <option> file\r\n"
				.AS "   -D : Debug Mode\r\n"
				.AS "   -T : Trace On"
MSG.ECHOCRLF	.AZ "\r\n"
MSG.DEBUG		.AZ "pStack=%H"
MSG.ERR			.AZ "^\r\nLine #%D:"
MSG.PROMPT		.AZ "\e[?7hOK\r\n> "	Enable Line Wrap
MSG.PROMPTCRLF	.AZ "\e[?7l\r\n"		Disable Line Wrap
FMT.Byte		.AZ "%d "
FMT.int16		.AZ "%I "
*--------------------------------------
OptionList		.AS "DdTt"
OptionVars		.DA #bDebug,#bDebug,#bTrace,#bTrace
*--------------------------------------
EscChars		.AS 'DBAC'
EscChars.Cnt	.EQ *-EscChars
EscChars.Remap	.DA #C.BS,#C.VT,#C.LF,#C.FS
*--------------------------------------
KEYWORDS		.AT "DUP"				( n - n n ) Duplicate top of stack.
				.AT "DROP"				( n - ) Discard top of stack.
				.AT "SWAP"				( n1 n2 - n2 n1 ) Reverse top two stack items.
				.AT "OVER"				( n1 n2 - n1 n2 n1 ) Copy second item to top.
				.AT "ROT"				( n1 n2 n3 - n2 n3 n1 ) Rotate third item to top.
				.AT "-DUP"				( n - n ? ) Duplicate only if non-zero.
				.AT ">R"				( n - ) Move top item to return stack.
				.AT "R>"				( - n ) Retrieve item from return stack.
				.AT "R"					( - n ) Copy top of return stack onto stack.
				.AT "+"					( n1 n2 - sum ) Add.
				.AT "D+"				( d1 d2 - sum ) Add double-precision numbers.
				.AT "-"					( n1 n2 - diff ) Subtract (n1-n2).
				.AT "*"					( n1 n2 - prod ) Multiply.
				.AT "/"					( n1 n2 - quot ) Divide (n1/n2).
				.AT "MOD"				( n1 n2 - rem ) Modulo (remainder from division).
				.AT "/MOD"				( n1 n2 - rem quot ) Divide, giving remainder and quotient.
				.AT "*/MOD"				( n1 n2 - rem quot ) Multiply, then divide (n1*n2/n3), with double-precision intermediate.
				.AT "*/"				( n1 n2 - quot ) Like */MOD, but give quotient only.
				.AT "MAX"				( n1 n2 - max ) Maximum.
				.AT "MIN"				( n1 n2 - min ) Minimum.
				.AT "ABS"				( n - absolute ) Absolute value.
				.AT "DABS"				( d - absolute ) Absolute value of double-precision number.
				.AT "MINUS"				( n - -n ) Change sign.
				.AT "DMINUS"			( d - -d ) Change sign of double-precision number.
				.AT "AND"				( n1 n2 - and ) Logical bitwise AND.
				.AT "OR"				( n1 n2 - or ) Logical bitwise OR.
				.AT "XOR"				( n1 n2 - xor ) Logical bitwise exclusive OR.
				.AT "<"					( n1 n2 - f ) True if n1 less than n2.
				.AT ">"					( n1 n2 - f ) True if n1 greater than n2.
				.AT "="					( n1 n2 - f ) True if n1 equal to n2.
				.AT "0<"				( n - f ) True if top number negative.
				.AT "0="				( n - f ) True if top number zero.
*--------------------------------------
				.AT "."					( n - ) Print number.
				.AT ".R" 				( n u - ) Print number, right-justified in u column.
				.AT "D."				( d - ) Print double-precision number.
				.AT "D.R"				( d u - ) Print double-precision number in u column.
				.AT "CR"				( - ) Do a carriage-return.
				.AT "SPACE"				( - ) Type one space.
				.AT "SPACES"			( u - ) Type u spaces.
				.AT '."'				( - ) Print message (terminated by ").
				.AT "DUMP" 				( addr u - ) Dump u numbers starting at address.
				.AT "TYPE" 				( addr u - ) Type u characters starting at address.
				.AT "COUNT" 			( addr - addr+1 u ) Change length byte string to TYPE form.
				.AT "?TERMINAL" 		( - f ) True if terminal break request present.
				.AT "KEY"				( - c ) Read key, put ASCII value on stack.
				.AT "EMIT"				( c - ) Type ASCII character from stack.
				.AT "EXPECT"			( addr u - ) Read u characters (or until carriage-return) from input device to address.
				.AT "WORD"				( c - ) Read one word from input stream, delimited by c.
				.AT "NUMBER" 			( addr - d ) Convert string at address to double number.
				.AT "<#" 				( - ) Start output string.
				.AT "#" 				( d1 - d2 ) Convert one digit of double number and add character to	output string.
				.AT "#S" 				( d - 0 0 ) Convert all significant digits of double number to output string.
				.AT "SIGN"	 			( n d - d ) Insert sign of n to output string.
				.AT "#>" 				( d - addr u ) Terminate output string for TYPE.
				.AT "HOLD" 				( c - ) Insert ASCII character into output string.
				.AT "DECIMAL" 			( - ) Set decimal base.
				.AT "HEX" 				( - ) Set hexadecimal base.
				.AT "OCTAL" 			( - ) Set octal base.
*--------------------------------------
				.AT "@"					( addr - n ) Replace word address by contents.
				.AT "!"					( n addr - ) Store second word at address on top.
				.AT "C@"				( addr - b ) Fetch one byte only.
				.AT "C!"				( b addr - ) Store one byte only.
				.AT "?"					( addr - ) Print contents of address.
				.AT "+!"				( n addr - ) Add second number to contents of address.
				.AT "CMOVE"				( from to u - ) Move u bytes in memory.
				.AT "FILL"				( addr u b - ) Fill u bytes in memory with b beginning at address.
				.AT "ERASE"				( addr u - ) Fill u bytes in memory with zeros.
				.AT "BLANKS"			( addr u - ) Fill u bytes in memory with blanks.
				.AT "HERE"				( - addr ) Return address above dictionary.
				.AT "PAD"				( - addr ) Return address of scratch area.
				.AT "ALLOT"				( u - ) Leave a gap of n bytes in the dictionary.
				.AT ","					( n - ) Compile number n into the dictionary.
				.AT "'"					( - addr ) Find address of next string in dictionary.
				.AT "FORGET"			( - ) Delete all definitions above and including the following definition.
				.AT "DEFINITIONS"		( - ) Set current vocabulary to context vocabulary.
				.AT "VOCABULARY"		( - ) Create new vocabulary.
				.AT "FORTH"				( - ) Set context vocabulary to Forth vocabulary.
				.AT "EDITOR"			( - ) Set context vocabulary to Editor vocabulary.
				.AT "ASSEMBLER"			( - ) Set context vocabulary to Assembler.
				.AT "VLIST"				( - ) Print names in context vocabulary.
*--------------------------------------
				.AT ":"					( - ) Begin a colon definition.
				.AT ";"					( - ) End of a colon definition.
				.AT "VARIABLE"			( n - ) Create a variable with initial value n.
				.AT "CONSTANT"			( n - ) Create a constant with value n.
				.AT "CODE"				( - ) Create assembly-language definition.
				.AT ";CODE"				( - ) Create a new defining word, with runtime code routine in high-level Forth.
				.AT "DO"				( end+1 start - ) Set up loop, given index range.
				.AT "LOOP"				( - ) Increment index, terminate loop if equal to limit.
				.AT "+LOOP"				( n - ) Increment index by n. Terminate loop if outside limit.
				.AT "I"					( - index ) Place loop index on stack.
				.AT "LEAVE"				( - ) Terminate loop at next LOOP or +LOOP.
				.AT "IF"				( f - ) If top of stack is true, execute true clause.
				.AT "ELSE"				( - ) Beginning of the false clause.
				.AT "ENDIF"				( - ) End of the IF-ELSE structure.
				.AT "BEGIN"				( - ) Start an indefinite loop.
				.AT "UNTIL"				( f - ) Loop back to BEGIN until f is true.
				.AT "REPEAT"			( - ) Loop back to BEGIN unconditionally.
				.AT "WHILE"				( f - ) Exit loop immediately if f is false.
*--------------------------------------
				.AT "("					( - ) Begin comment, terminated by ).
*--------------------------------------
				.DA #0
*--------------------------------------
				.DUMMY
				.OR 0
DS.START		.BS 128					RETURN STACK		

bDebug			.BS 1
bTrace			.BS 1
bExitOnEOF		.BS 1

hCodeBuf		.BS 1
CodeBuf			.BS 2

hDataBuf		.BS 1
DataBuf			.BS 2

hInputBuf		.BS 1
InputBuf		.BS 2

hOutputBuf		.BS 1
OutputBuf		.BS 2

hCLBuf			.BS 1
hFile			.BS 1
hSList			.BS 1

DS.END			.ED
*--------------------------------------
MAN
SAVE usr/src/bin/forth.s
ASM