;	--------------------------------------------------------------
;			 HJELP.ASM Copyright (C) 1984
;			Universidad Autonoma de Puebla
;
;	[HELP.xxx (SIG/M xxx.xx) Richard Conn]
;	[HELP8080.ASM (SIG/M 122.03) = original model]
;	[squeezed HELP files - Harold V. McIntosh, July 20, 1984]
;	["L" backs up to panel 1 - 20 Jul 84 - HVM]
;	[Library files - 5 October 1984]
;	--------------------------------------------------------------

CR	equ	0DH
VT	equ	0CH
LF	equ	0AH
HT	equ	09H

X0004	equ	0004H		;CP/M Disk Byte
X0005	equ	0005H		;call point to BDOS
tfcb	equ	005CH		;CP/M's file control block
tbuf	equ	0080H		;CP/M's I-O buffer

bred	equ	4000H		;red screen area
bgrn	equ	6000H		;green screen area
bblu	equ	8000H		;blue screen area

NH	equ	6		;number of HELP file names to print per line
ND	equ	10		;maximum node depth
NS	equ	9		;bytes to save for panel markers

csiz	equ	257
psiz	equ	50*NS		;textpointer pushdown size

;	-------------
	org	0100H
;	-------------

begn:	lxi	h,0000
	dad	sp
	shld	X0D31		;save stack
	lxi	sp,X0D31	;stack
	lda	tfcb+1		;TFCB+1
	cpi	' '
	jnz	nnul
	lxi	d,tuto		;'tutorial'
ferm:	call	mssg
gbye:	lhld	X0D31		;save stack
	sphl
	ret

nnul:	lda	X0005+2
	sui	0AH
	sta	X0C63		;memory pages
	lxi	h,nbuf+1
	mvi	m,' '
	xra	a
	sta	X0C71		;level #
	lxi	d,X08BE		;'signon'
	call	mssg		;message to console
	lda	tfcb+1
	cpi	'('
	jnz	loop
	lxi	h,tbuf
	mov	b,m
	inx	h
	xchg
	lxi	h,obuf
	shld	optr
	call	miuc
	mvi	m,00
	lxi	d,lohf		;'loading HELP file'
	call	mssg
	call	pafr
	lxi	h,nbuf+1
	mov	a,m
	cpi	' '
	jnz	ymbr
	lxi	d,tfcb+1
	mvi	b,8
	call	miuc
	call	phlp
	jmp	loop

ymbr:	lxi	h,nbuf+9
	mov	a,m
	cpi	' '
	cz	phlp

;	Loop.

loop:	lxi	sp,X0D31	;stack
	lxi	h,tfcb+9
	mov	a,m
	cpi	' '
	cz	phlp
	lxi	h,tfcb		;TFCB
	mvi	m,000H
	lxi	d,000CH
	dad	d

;	Zero out tail of FCB.

	mvi	b,018H		;24
X01C9:	mvi	m,000H
	inx	h
	dcr	b
	jnz	X01C9

	lxi	h,0FFFFH
	shld	mlen

ldfi:	call	opef
	call	sefl
	mvi	m,1AH		;^Z
	call	desq
	jmp	gogo

sefl:	lxi	h,X0D33		;beginning of free memory
sefm:	lda	X0C63
	cmp	h
	jz	X04D1		;'not enough room'
	call	rerb
	jc	sefn
	mov	m,a
	inx	h
	jmp	sefm

sefn:	shld	X0C6E		;ptr end of text
	ret

;	------------------------------------
;	opef will open file even within .LBR
;	ofil will open a normal file

;	Test for .LBR file.

opef:	lda	nbuf+1
	cpi	' '
	jz	ofil

;	-----------------------------------------
;	Open a .LBR file to the member specified
;	at nbuf+1 of the .LBR file referenced by
;	tfcb. Termination results if either item
;	cannot be found, otherwise the next read
;	will pick up the desired member.
;	----------------------------------------

;	Open .LBR file, read first record.

olbr:	mvi	c,15		;(0F) open file
	lxi	d,tfcb
	call	X0005

	inr	a
	jnz	fopn
	lxi	d,nlib		;'requested library not found'
	jmp	ferm		;send message to console

fopn:	lxi	h,tfcb+32
	mvi	m,00
	lxi	h,0000
	shld	mctr		;counter for tbuf
	dcx	h
	shld	mlen		;length (records) of member

	call	afil		;fill "A" buffer
	lhld	abuf+14		;length of LBR dir
	shld	mlen		;length (records) of member
	dad	h
	dad	h
	shld	rlen		;length (32-byte lines) of directory

;	Library member was requested, so look it up in directory.

tmem:	lhld	rlen		;length (32-byte lines) of directory
	dcx	h
	shld	rlen		;length (32-byte lines) of directory
	mov	a,h
	ora	l
	jnz	tmen
	lxi	d,nfil		;'requested file not present'
	call	ferm		;message to console

tmen:	call	afil		;read a directory line
	mvi	b,11
	lxi	d,abuf+1
	lxi	h,nbuf+1	;member name buffer
	call	ciuc		;block compare
	jnz	tmem

;	Record length and whether 'Q' in extension.

	lhld	abuf+14
	shld	mlen		;length (records) of member
	lxi	h,dens		;z/nz=un/squeezed
	mvi	m,0
	lda	abuf+10
	cpi	'Q'
	jnz	sefi
	dcr	m

;	Advance to the proper section of the library.
;	This is not an elegant way to do it, but it avoids
;	computing with CP/M extents and record sizes.

sefi:	mvi	c,15		;(0F) open file
	lxi	d,tfcb
	call	X0005
	xra	a
	sta	tfcb+32

;	Skip up to (but don't read) beginning of member.

sefj:	lhld	abuf+12
	mov	a,h
	ora	l
	jz	sefk
	dcx	h
	shld	abuf+12
	mvi	c,20		;(14) read one record
	lxi	d,tfcb
	call	X0005
	jmp	sefj

sefk:	lxi	h,0000
	shld	mctr
	ret

;	Fill the "A" buffer, which holds .LBR directory lines.

afil:	mvi	c,20H
	lxi	h,abuf		;"A" buffer = line of LBR dir
afim:	call	rerb
	mov	m,a
	inx	h
	dcr	c
	jnz	afim
	ret

;	Read a byte from tbuf, replenishing as necessary.
;	Carry signifies End of File.

rerb:	push	h
	lhld	mctr		;counter for tbuf
	mov	a,h
	ora	l
	stc
	cz	rerx		;read one record
	cmc
	dcx	h
	shld	mctr		;counter for tbuf
	lhld	mptr		;pointer for tbuf
	mov	a,m
	inx	h
	shld	mptr		;pointer for tbuf
	pop	h
	ret

;	Read another record, but don't read past the number
;	allocated to the member. Likewise, we have to be careful
;	about an ASCII file which ends exactly on a record boundary.

rerx:	lhld	mlen		;length (records) of member
	mov	a,h
	ora	l
	jz	rery
	dcx	h
	shld	mlen		;length (records) of member
	push	b
	push	d
	mvi	c,20		;(14) read one record
	lxi	d,tfcb
	call	X0005
	pop	d
	pop	b
	ora	a
	jnz	rery
	lxi	h,tbuf
	shld	mptr		;pointer for tbuf
	lxi	h,0080H
	stc
	ret

;	Squeezed files should end with a special end
;	of file marker (non-1-byte 100H), which has to be seen
;	to terminate the file. ASCII files normally terminate with
;	a ^Z, but this may be implicit if the file exactly fills a
;	record.

rery:	lxi	h,tbuf
	shld	mptr
	mvi	m,1AH		;^Z
	lxi	h,0001H
	stc
	cmc
	ret

;	Open an ordinary file. If not found, try for a squeezed
;	version instead.

ofil:	lxi	h,0000
	shld	mctr
	dcx	h
	shld	mlen
	xra	a
	sta	tfcb+32
	sta	dens
ofim:	lxi	d,tfcb		;TFCB
	mvi	c,15		;(0F) open file
	call	X0005		; B D O S
	inr	a
	rnz
	lxi	h,tfcb+10
	mov	a,m
	mvi	m,'Q'
	cmp	m
	jnz	ofim
	lxi	d,nfil		;'no file'
	jmp	ferm

;	------------------------

;	Decide whether it is a squeezed file.

desq:	lxi	h,X0D33
	shld	tptr		;text pointer
	shld	xptr		;ptr to bgn of HELP file
	lxi	h,dens		;z/nz = normal/squeezed file
	mvi	m,0
	lxi	h,wflg		;z/nz = no/byte left waiting by abyt
	mvi	m,0
	call	gbyt		;one byte, direct or through onsq
	cpi	076H
	jnz	unjj
	call	gbyt		;one byte, direct or through onsq
	cpi	0FFH
	jz	unii
unjj:	lxi	h,X0D33
	shld	tptr		;text pointer
	ret

;	Squeezed, so go through initialization

unii:	lxi	h,rcnt		;repetition count
	mvi	m,0
	lxi	h,roco		;bit rotation counter
	mvi	m,1

;	The "squeezed" marker is followed by a two-byte checksum,
;	which is the simple sum of all the one-byte characters in
;	the source file, carried as a two byte sum modulo 2**16.

rchk:	call	iwor		;fetch two bytes from input stream
	shld	cksm		;checksum

;	Unsqueezed file name. It is an ASCII sequence, may be lower
;	case if SQ.COM received it in response to a prompt, ending
;	with a zero byte.

luup:	call	gbyt		;fetch one byte from input stream
	ora	a
	jnz	luup

;	Load code dictionary. It is preceded by its two-byte length,
;	and consists of a series of pairs of two-byte addresses. For
;	each bit in the code, select the first element (0) or the
;	second (1) element of the pair. If the pair is positive, it
;	is the table entry (code + 4*index) at which to continue with
;	the next bit. If the pair is negative, it is the complement
;	of the coded ASCII character (low order byte except for [end]).

ldic:	call	iwor		;fetch two bytes from input stream
	dad	h
	dad	h
	xchg
	lhld	tptr		;text pointer
	shld	cptr		;Huffman code table
	dad	d
	shld	tptr		;text pointer
	shld	xptr		;ptr to bgn of HELP file
	lxi	h,dens
	mvi	m,0FFH
	ret

;	Scan the HELP text to find and record the section headings.

gogo:	lxi	h,pudl
	shld	pptr		;pushdown pointer
	lxi	h,mopt
	mvi	m,'A'		;A, not @, to make <cmp m, jnc> work
	call	abyt		;lookahead one byte
	cpi	':'
	jz	gogu
gugu:	call	rbyt		;fetch one byte
	cpi	LF
	jnz	gigi
	call	rbyt		;fetch one byte
	cpi	':'
	jz	gege
gigi:	cpi	1AH
	jz	gogu
	jmp	gugu

gege:	call	pupu
	lxi	h,mopt		;maximum option
	inr	m
	jmp	gugu

gogu:	lhld	pptr		;pushdown pointer
	shld	zptr		;ptr to bgn of info sect
	lhld	xptr		;ptr to bgn of HELP file
	shld	tptr		;text pointer
	lxi	h,roco		;bit rotation counter
	mvi	m,1
	lxi	h,wflg		;z/nz = no/byte left waiting by abyt
	mvi	m,0

;	Display menu. Here we distinguish between a simple HELP
;	file which begins with a colon and has only one section,
;	and an indexed HELP file, which starts out with a list of
;	section descriptors.

X0342:	lxi	sp,X0D31	;stack
	mvi	a,000H
	sta	X0C72		;panel #
	call	abyt		;lookahead one byte
	cpi	'!'
	jc	xxxx
	cpi	':'
	jnz	X036A		;show menu, request option
	call	rbyt		;fetch one byte
xxxx:	call	X05E5		;initialize new section
	lda	X0C71		;level #
	ora	a
	jz	gbye		;return to CP/M
	jmp	X07ED		;go up one level

;	Return to CP/M

;	Show menu, request option.

X036A:	call	X058D		;run through the menu
	push	b
	call	crlf		;CR,LF
	call	X0859		;type level I.D.
	lxi	d,X0C19		;'Type [^C]'
	call	mssg		;message to console
	lxi	d,X0C27		;'Type [level or root]'
	lda	X0C71		;level #
	ora	a
	jz	X0387
	call	mssg		;message to console
X0387:	lxi	d,X0C37		;'Enter Selection'
	call	mssg		;message to console
	pop	b
	call	X046B		;read char from console
	cpi	003H		;^C
	jz	gbye		;return to CP/M
	cpi	'.'
	jz	X07E1		;back to root
	cpi	'^'
	jz	X07ED		;go up one level
	push	psw
	call	crlf		;CR,LF
	pop	psw
	lxi	h,mopt		;maximum option
	cmp	m
	jnc	X03AE
	sui	'@'
	jc	X03AE
	jz	X03AE
	call	anth		;access nth option
	call	X05E5		;initialize new section
	jmp	X036A		;show menu, request option

X03AE:	lxi	d,X0AC6		;'Invalid Response'
	call	mssg		;message to console
	jmp	X036A		;show menu, request option

;	Insert extension .HLP

phlp:	mvi	m,'H'
	inx	h
	mvi	m,'L'
	inx	h
	mvi	m,'P'
	ret

;	Read a character from the console.

X046B:	push	b
	push	d
	push	h
	mvi	c,1		;(01) console input
	call	X0005		; B D O S
	pop	h
	pop	d
	pop	b
	push	psw
	call	crlf		;CR,LF
	pop	psw
X047B:	ani	07FH		;upper case fold
	cpi	'a'
	rc
	cpi	'{'
	rnc
	ani	05FH
	ret

;	CR, LF.

crlf:	mvi	a,CR
	call	cona		;char to console
	mvi	a,LF
	jmp	cona		;char to console

;	Character to console.

cona:	push	psw
	push	b
	push	d
	push	h
	mvi	c,2		;(02) console output
	mov	e,a
	call	X0005		; B D O S
	pop	h
	pop	d
	pop	b
	pop	psw
	ret

;	Message to Console.

mssg:	push	b
	push	d
	push	h
	mvi	c,9		;(09) print string to $
	call	X0005		; B D O S
	pop	h
	pop	d
	pop	b
	ret

;	Type file name.

tyfn:	mov	a,m
	cpi	' '
	rz
	mvi	b,8
	call	tyfo
	mov	a,m
	cpi	' '
	rz
	mvi	a,'.'
	call	cona
	mvi	b,3
tyfo:	mov	a,m
	inx	h
	cpi	' '
	cnz	cona
	dcr	b
	jnz	tyfo
	ret

;	Compare B bytes between (HL) and (DE)

ciuc:	ldax	d
	cmp	m
	rnz
	inx	d
	inx	h
	dcr	b
	jnz	ciuc
	ret

;	Move B bytes from (DE) to (HL).

miuc:	ldax	d
	mov	m,a
	inx	d
	inx	h
	dcr	b
	jnz	miuc
	ret

;	Move B bytes from (HL) to (DE)

mduc:	dcx	h
	dcx	d
	mov	a,m
	stax	d
	dcr	b
	jnz	mduc
	ret

;	Initialize pudl.

izpu:	mvi	b,NS
	lxi	d,lach
	lhld	zptr		;ptr to bgn of info sect
	call	miuc
	shld	yptr		;zptr+NS
	shld	pptr		;pushdown pointer
	lxi	h,X0C72		;panel #
	mvi	m,1
	ret

;	Restore to the head of pudl.

rspu:	mvi	b,NS
	lhld	yptr		;zptr+NS
	shld	pptr		;pushdown pointer
	lxi	d,lach+NS
	call	mduc
	lxi	h,X0C72		;panel #
	mvi	m,0
	ret

;	Access nth option.

anth:	mov	e,a
	mvi	d,0
	mov	l,e
	mov	h,d
	dad	h
	dad	h
	dad	h
	dad	d
	lxi	d,pudl
	dad	d
	lxi	d,lach+NS
	mvi	b,NS
	call	mduc
	lhld	zptr		;ptr to bgn of info sect
	shld	pptr		;pushdown pointer
	lxi	h,X0C72
	mvi	m,1
	ret

;	Push state onto pudl.

pupu:	lhld	pptr		;pushdown pointer
	lxi	d,pudl+psiz
	mov	a,l
	sub	e
	mov	a,h
	sbb	d
	rnc
	mvi	b,NS
	lxi	d,lach
	call	miuc
	shld	pptr		;pushdown pointer
	lxi	h,X0C72		;panel #
	inr	m
	ret

;	Pop state from pudl.

popu:	lhld	zptr
	xchg
	lhld	pptr		;pushdown pointer
	mov	a,e
	sub	l
	mov	a,d
	sbb	h
	rnc
	mvi	b,NS
	lxi	d,lach+NS
	call	mduc
	shld	pptr		;pushdown pointer
	lxi	h,X0C72		;panel #
	mov	a,m
	ora	a
	rz
	dcr	m
	ret

X04D1:	lxi	d,X0BDC		;'Not Enough Room'
	jmp	ferm

onsq:	lda	rcnt		;repetition count
	ora	a
	jnz	onsr
	call	dnch		;decode next character
	jc	vchk		;verify the checksum
	cpi	090H		;repeat last character
	jnz	onsu		;normal character
	call	dnch		;decode next character
	ora	a
	jz	onss
	dcr	a
onsr:	dcr	a
	sta	rcnt		;repetition count
	lda	lach
	jmp	achk

onss:	mvi	a,090H
	jmp	achk

onsu:	sta	lach		;last character typed
	jmp	achk

;	Decode next character.

dnch:	lhld	cptr		;Huffman code table
dncr:	call	ibit		;read next bit
	jnc	dncs		;skip for 1, stay for 0
	inx	h
	inx	h
dncs:	mov	e,m		;get next offset
	inx	h
	mov	d,m
	mov	a,d
	cpi	0FEH		;FEFF means [end]
	jz	dnct
	ora	a
	jp	dncu		;p means new offset
	mov	a,e		;m means complemented char
	cma
	stc
	cmc
	ret

dnct:	stc			;flag [end] with carry bit
	ret

;	Calculate <code>+4*<offset>.

dncu:	lhld	cptr		;Huffman code table
	dad	d
	dad	d
	dad	d
	dad	d
	jmp	dncr

;	Read one bit at a time.

ibit:	push	h
	lxi	h,roco		;bit rotation counter
	dcr	m
	jnz	ibiu
	mvi	m,8
	call	ibyt		;fetch one byte from input stream
	sta	roby		;rotating byte
ibiu:	lda	roby		;rotating byte
	rar
	sta	roby		;rotating byte
	pop	h
	ret

;	Read one word.

iwor:	call	ibyt		;fetch one byte from input stream
	mov	l,a
	push	h
	call	ibyt		;fetch one byte from input stream
	pop	h
	mov	h,a
	ret

;	Accumulate checksum.

achk:	lxi	h,cksm
	mov	b,a
	mov	a,m
	sub	b
	mov	m,a
	inx	h
	mov	a,m
	sbi	0
	mov	m,a
	mov	a,b
	stc
	cmc
	ret

;	Verify the checksum.

vchk:	lhld	cksm		;checksum
	mov	a,l
	ora	h
	stc
	rz			;return to CP/M
	lxi	d,chno		;'Checksum failure.'
	jmp	ferm		;fatal error message

abyt:	push	h
	lxi	h,wflg		;z/nz = no/byte left waiting by abyt
	mov	a,m
	ora	a
	jz	abyy
	lda	wbyt		;byte left waiting by abyt
	jmp	abyr
abyy:	dcr	m
	call	gbyt		;one byte, direct or through onsq
	sta	wbyt		;byte left waiting by abyt
abyr:	pop	h
	ret

rbyt:	lda	wflg		;z/nz = no/byte left waiting by abyt
	ora	a
	jz	gbyt		;one byte, direct or through onsq
	mvi	a,0
	sta	wflg		;z/nz = no/byte left waiting by abyt
	lda	wbyt		;byte left waiting by abyt
	ret

gbyt:	lda	dens		;one byte, direct or through onsq
	ora	a
	jz	ibyt
	push	h
	call	onsq		;one byte from squeezed file
	pop	h
	ret

ibyt:	push	h		;fetch byte from the input stream
	push	d
	lhld	X0C6E		;ptr end of text
	xchg
	lhld	tptr		;text pointer
	mov	a,l
	sub	e
	mov	a,h
	sbb	d
	mov	a,m
	inx	h
	shld	tptr		;text pointer
	cmc
	pop	d
	pop	h
	ret

;	Type line, solicit option.

X04DA:	call	rbyt		;fetch one byte
	cpi	CR
	jz	X04F4		;type options at bottom of panel
	cpi	LF
	jz	X04F5		;type options at bottom of panel
	cpi	01AH		;^Z
	jz	X04F5		;type options at bottom of panel
	call	cona		;char to console
	jmp	X04DA		;type line, solicit option

;	Type the options at bottom of panel.
;	Entry point according to how line ended.

X04F4:	call	rbyt		;decomission following LF
X04F5:	call	crlf		;CR,LF
	lxi	h,X0C6B		;console remaining lines
	dcr	m
	rnz

;	Solicit options (without marking or incrementing line).

X0504:	call	X0859		;type level I.D.
	lxi	d,X097A		;'^C = Exit'
	call	mssg		;message to console
X050D:	lxi	d,X0983		;'[level, root]'
	lda	X0C71		;level #
	ora	a
	jz	X0521
	call	mssg		;message to console
X0521:	lxi	d,X0993		;'[option list]'
	call	mssg		;message to console
	call	X046B		;read char from console
	sta	char		;char read from console
	cpi	'M'
	jnz	pnla
	jmp	X0342		;display menu

pnla:	cpi	003H		;^C
	jnz	pnlb
	jmp	gbye		;return to CP/M

pnlb:	cpi	'P'
	jnz	pnlc
	jmp	X06FE		;fulfil PRINT request

pnlc:	cpi	'.'
	jnz	pnld
	jmp	X07E1		;back to root

pnld:	cpi	'^'
	jnz	pnle
	jmp	X07ED		;go up one level

pnle:	cpi	'L'
	jnz	pnlf
	call	popu
	call	popu
	jmp	pnlg

pnlf:	cpi	'S'
	jnz	pnlg
	call	rspu		;restore start of info section
pnlg:	call	pupu		;save reference to section head
	call	X0587		;reset line count
	jmp	crlf		;CR,LF

;	Reset line count.

X0587:	mvi	a,23		;lines per screen panel
	sta	X0C6B		;console remaining lines
	ret

;	Run through the menu.

X058D:	mvi	a,000H
	sta	X0C72		;panel #
	lhld	xptr		;ptr to bgn of HELP file
	shld	tptr		;text pointer
	lxi	h,roco		;bit rotation counter
	mvi	m,1
	lxi	h,wflg		;z/nz = no/byte left waiting by abyt
	mvi	m,0
	call	X0587		;reset line count
	lxi	h,X0C6B		;console remaining lines
	dcr	m
	mvi	a,'A'
	sta	X0C68		;option letter
	lxi	d,X0954		;'Selections are ...'
	call	mssg		;message to console
	mvi	c,000H
X05AC:	call	abyt		;lookahead one byte
	cpi	':'
	jz	X05D4		;finish panel w/CR,LF's
	cpi	01AH		;^Z
	jz	gbye		;return to CP/M
	inr	c
	lda	X0C68		;option letter
	call	cona		;char to console
	inr	a
	sta	X0C68		;option letter
	mvi	a,'.'
	call	cona		;char to console
	mvi	a,' '
	call	cona		;char to console
	call	X04DA		;type line, solicit option
	jmp	X05AC

;	Finish out panel with CR, LF's.

X05D4:	lda	X0C6B		;console remaining lines
	mov	b,a
	ora	a
	rz
X05DD:	call	crlf		;CR,LF
	dcr	b
	jnz	X05DD
	ret

;	A loop which will print out an information section. It calls
;	X04DA, which will count out lines as it types them. If the
;	line it has just typed is the last one of the panel, it
;	will pause for the panel to be read, having solicited some
;	indication of whether it should procede, repeat the last panel,
;	go back to the beginning, or go back to the menu.

X05E5:	call	X075D		;is section disk file?
	call	izpu
	call	X0587		;reset line count
X05FA:	call	abyt		;lookahead one byte
	cpi	01AH		;^Z
	jz	X0624		;mark panel, type legend, read option
	cpi	':'
	jz	X0624		;mark panel, type legend, read option
	cpi	VT		;form feed
	jz	X05FB
	call	X04DA
	jmp	X05FA

X05FB:	call	rbyt		;fetch one byte
	lda	X0C6B		;console remaining lines
X061A:	push	psw
	call	X04F5		;type options at bottom of panel
	pop	psw
	dcr	a
	jnz	X061A
	jmp	X05FA

;	Mark panel, type legend, select option.

X0624:	call	rbyt		;fetch one byte
X0628:	call	crlf		;CR,LF
	lxi	h,X0C6B		;console remaining lines
	dcr	m
	jnz	X0628
X0635:	call	X0859		;type level I.D.
	lxi	d,X0976		;'EOI & ^C'
	call	mssg		;message to console
	call	X050D
	lda	char		;char read from console
	cpi	'L'
	jz	X05FA
	cpi	'S'
	jz	X05FA
	cpi	'P'
	jz	X05FA
	ret

;	Send line to LST:, check for interrupt request.

X06B3:	call	rbyt		;fetch one byte
	cpi	CR
	jz	X06CE		;list CR, LF's at end of line
	cpi	LF
	jz	X06CF		;list CR, LF's at end of line
	cpi	01AH		;^Z
	jz	X06CF		;list CR, LF's at end of line
	call	X06E4		;list output, read status
	jnz	X06B3		;line to LST:
	ret

;	Type CR, LF at end of line. Entry point according
;	to whether CR, LF, or ^Z was encountered.

X06CE:	call	rbyt		;decomission following LF
X06CF:	mvi	a,CR
	call	X06E4		;list output, read status
	rz			;to catch a ^C between CR, LF
	mvi	a,LF
X06E4:	push	h
	push	d
	push	b
	mov	e,a
	mvi	c,5		;(05) list output
	call	X0005		; B D O S
	mvi	e,0FFH
	mvi	c,6		;(06) direct console I/O
	call	X0005		; B D O S
	pop	b
	pop	d
	pop	h
	cpi	003H
	ret

;	Respond to PRINT request.

X06FE:	lxi	d,X09DE		;'Set Top-of-Form'
	call	mssg		;message to console
	xra	a
	sta	X0C61		;z/nz = panel/section (P)
	call	popu
	call	pupu
	call	X046B		;read char from console
	cpi	003H		;^Z
	jz	X071B
	cpi	'S'
	jz	X0718
	call	rspu
	call	pupu
	mvi	a,0FFH
	sta	X0C61		;z/nz = panel/section (P)
X0718:	call	X0730
X071B:	call	popu
	jmp	pnlg

X0730:	lxi	d,X09B2		;'Printing in Progress ...'
	call	mssg		;message to console
	call	X0587		;reset line count
X0739:	call	X06B3		;line to LST:
	cpi	003H		;^C
	rz
	call	abyt		;lookahead one byte
	cpi	01AH		;^Z
	rz
	cpi	':'
	rz
	cpi	VT		;Form Feed
	cz	X06CF		;list CR, LF's at end of line
	lda	X0C61		;z/nz = panel/section (P)
	ora	a
	jnz	X0739
	lxi	h,X0C6B		;console remaining lines
	dcr	m
	jnz	X0739
	ret

;	Check whether section is a disk file.

X075D:	call	abyt		;lookahead one byte
	cpi	':'
	rnz
	call	rbyt
	lda	X0C71		;level #
	cpi	ND		;maximum node depth
	jnz	X0776		;read file, type name
	lxi	d,X0B4A		;'Node Limit'
	call	mssg		;message to console
	jmp	gbye		;return to CP/M

;	Type name, read file.

X0776:	call	X0845		;locate file name on stack
	lxi	d,tfcb+1	;TFCB+1
	mvi	b,11		;bytes in file name
	call	miuc
	mvi	b,11
	lxi	d,nbuf+1
	call	miuc
	lxi	h,X0C71		;level #
	inr	m

;	If there can be several color overlays and the like,
;	we have to set aside the panel defining them so that
;	the space it occupies can be used for loading.

	mvi	b,0
	lxi	d,0000
	lxi	h,obuf
	shld	optr
olay:	call	rbyt
	jc	loaz
	cpi	1AH		;^Z
	jz	loaz
	cpi	':'
	jnz	olax
	mvi	a,LF
	cmp	b
	jz	loaz
	mvi	a,':'
olax:	mov	m,a
	mov	b,a
	inx	d
	inx	h
	cpi	':'
	jnz	olay
	call	rbyt
	cpi	':'
	jnz	loaz
	jmp	olay

loaz:	xchg
	shld	octr
	jmp	colo

;	Subroutine which will read out the bytes saved from
;	the instruction panel when overlays are to be used.

obyt:	push	h
;	lhld	octr
;	mov	a,h
;	ora	l
;	jz	obyz
;	dcx	h
;	shld	octr
	lhld	optr
	mov	a,m
	inx	h
	shld	optr
obyz:	pop	h
	ret

;	Load any requested overlays.

colo:	lxi	d,lohf		;'Loading HELP File'
	call	mssg		;message to console

	lxi	h,dest
	mvi	m,' '

	call	pafr		;parse file reference.
	jmp	coov		;execute it

;	Parse a file reference, and type it.

pafr:	mvi	a,' '
	sta	nbuf+1
paff:	call	obyt
	cpi	' '
	jz	paff
	cpi	'('
	jz	ylbr
	lxi	h,tfcb
	call	pars
	cpi	')'
	jz	wlbr
	lxi	h,tfcb+1
	jmp	tyfn

ylbr:	lxi	h,tfcb
	call	part
wlbr:	lxi	h,nbuf
	call	part

;	Insert extension .LBR if none was given.

	lxi	h,tfcb+9
	mov	a,m
	cpi	' '
	jnz	ylbs
	mvi	m,'L'
	inx	h
	mvi	m,'B'
	inx	h
	mvi	m,'R'

ylbs:	mvi	a,'('
	call	cona
	lxi	h,tfcb+1
	call	tyfn
	mvi	a,')'
	call	cona
	mvi	a,' '
	call	cona
	lxi	h,nbuf+1
	jmp	tyfn

;	Check for color overlay.

coov:	lxi	h,dest
	mov	a,m
	mvi	m,' '
	cmp	m
	jnz	coow
	call	crlf
	jmp	loop		;loop

coow:	cpi	'R'
	jnz	gree
	call	opef
	call	sefl
	call	desq
	lxi	h,bred		;red screen area
	call	lcbf
	jmp	colo

gree:	cpi	'G'
	jnz	blue
	call	opef
	call	sefl
	call	desq
	lxi	h,bgrn		;green screen area
	call	lcbf
	jmp	colo

blue:	cpi	'B'
	jnz	colo
	call	opef
	call	sefl
	call	desq
	lxi	h,bblu		;blue screen area
	call	lcbf
	jmp	colo

;	Load color buffer. HL designates the buffer.

lcbf:	lda	oper
	cpi	'='
	jnz	ocbf
ldbf:	call	rbyt
	jc	colo
	mov	m,a
	inx	h
	jmp	ldbf

ocbf:	cpi	'+'
	jnz	xcbf
odbf:	call	rbyt
	jc	colo
	ora	m
	mov	m,a
	inx	h
	jmp	odbf

xcbf:	cpi	'-'
	jnz	colo
xdbf:	call	rbyt
	jc	colo
	xra	m
	mov	m,a
	inx	h
	jmp	xdbf

;	---------------------------------------------
;	Parse disk, filename, extension. HL points to
;	FCB, new characters arrive via <call obyt>.
;	---------------------------------------------

;	Pass over leading blanks.
;	  <call part> to ignore A
;	  <call pars> to test A first

part:	call	obyt
pars:	cpi	' '
	jz	part

	call	term
	rz			;null buffer

;	Insert filename field. If a disk unit is specified,
;	record it in the first byte of the FCB, then try again
;	for the filename. Likewise, if a destination is given,
;	note it.

	mvi	m,0
infn:	inx	h
infi:	push	h
	mvi	b,8
	call	stof
	call	oprn
	jnz	dsku
	sta	oper
	pop	h
	mov	a,m
	sta	dest
	call	obyt
	cpi	'('
	jnz	infi
	call	obyt
	jmp	infi

dsku:	cpi	':'
	jnz	inxt
	pop	h
	mov	a,m
	sui	'@'
	mov	m,a
	dcx	h
	call	obyt
	jmp	infn

;	Insert extension field.

inxt:	inx	sp
	inx	sp
	mvi	b,3
	cpi	'.'
	jnz	shof
	call	obyt

;	Store field.

stof:	mov	m,a
	inx	h
	dcr	b
	jz	lonf
	call	obyt
	call	term		;z=terminator
	jnz	stof

;	Complete short field with blanks.

shof:	mvi	m,' '
	inx	h
	dcr	b
	jnz	shof
	ret

;	Ignore remainder of long field.

lonf:	call	obyt
	call	term		;z=terminator
	jnz	lonf
	ret

;	Check for a field terminator (z).
;	Check for an operation (z).

term:	cpi	'.'
	rz
	cpi	' '
	rz
	cpi	':'
	rz
	cpi	')'
	rz
	cpi	CR
	rz
	ora	a
	rz
oprn:	cpi	'='
	rz
	cpi	'+'
	rz
	cpi	'-'
	ret

;	------------------------

;	Go back to root.

X07E1:	lda	X0C71		;level #
	ora	a
	jz	X0342		;display menu
	mvi	a,000H
	jmp	X07FE

;	Go up one level.

X07ED:	lda	X0C71		;level #
	ora	a
	jnz	X07FD		;revert to last level
	lxi	d,X0BAD		;'No Higher Level'
	call	mssg		;message to console
	jmp	X0342		;display menu

;	Revert to upper level, type name.

X07FD:	dcr	a
X07FE:	sta	X0C71		;level #
	call	X0845		;locate file name on stack
	push	h
	lxi	d,lohf		;'Loading HELP File'
	call	mssg		;message to console
	call	tyfn		;type filename
	call	crlf
	pop	d
	lxi	h,tfcb+1	;TFCB+1
	mvi	b,11		;bytes in file name
	call	miuc
	mvi	b,11
	lxi	h,nbuf+1
	call	miuc
	jmp	loop		;loop

;	Locate file name on stack.

X0845:	call	X084D		;HL=A*22
	lxi	d,X0C73		;PDL for HELP file names
	dad	d
	ret

;	HL = A*22

X084D:	mov	l,a
	mvi	h,000H
	mov	e,l
	mov	d,h
	dad	h
	dad	h
	dad	h
	dad	d
	dad	d
	dad	d
	dad	h
	ret

;	Type level identification.

X0859:	lda	X0C71		;level #
	ora	a
	jz	X0872
	lxi	d,X0C0C		;'Level 1'
	call	mssg		;message to console
	lda	X0C71		;level #
	call	X0881		;translate level # to ASCII
	lxi	d,X0C13		;'/ '
	call	mssg		;message to console
X0872:	lda	X0C72		;panel #
	ora	a
	rz
	call	X0881		;translate level # to ASCII
	lxi	d,X0C16		;': '
	call	mssg		;message to console
	ret

;	Translate level number to ASCII string.

X0881:	push	psw
	xra	a
	sta	X0C70		;z/nz = 1/2 digit number
	pop	psw
	mvi	b,100		;one hundred
	call	X0896		;type A as decimal number
	mvi	b,10		;ten
	call	X0896		;type A as decimal number
	adi	'0'
	jmp	cona		;char to console

;	Type A as decimal number.

X0896:	mvi	c,000H
X0898:	sub	b
	jc	X08A0
	inr	c
	jmp	X0898

X08A0:	add	b
	mov	b,a
	lda	X0C70		;z/nz = 1/2 digit number
	ora	a
	jnz	X08B6
	mov	a,c
	sta	X0C70		;z/nz = 1/2 digit number
	ora	a
	jnz	X08B6
	mvi	a,' '
	jmp	X08B9

X08B6:	mov	a,c
	adi	'0'
X08B9:	call	cona		;char to console
	mov	a,b
	ret

X08BE:	db	'HJELP/ICUAP/05-OCT-84',CR,LF,'$'
tuto:	db	'Many systems feature HELP files containing information',CR,LF
	db	'about the usage or characteristics of the system itself',CR,LF
	db	'or the programs which it contains. HELP files are often',CR,LF
	db	'structured, and require an auxiliary program which will',CR,LF
	db	'facilitate their consultation. HJELP.COM satisfies this',CR,LF
	db	'requirement, even if the HELP files have been squeezed',CR,LF
	db	'or have been placed in a library.',CR,LF
	db	'		HJELP FILE',CR,LF
	db	'will display either FILE.HLP or FILE.HQP, using a menu',CR,LF
	db	'of information sections and a series of prompts which',CR,LF
	db	'are largely self-explanatory.',CR,LF
	db	'		HJELP (LIBR) FILE',CR,LF
	db	'will display FILE.HLP, taken from the library LIBR.LBR.',CR,LF
	db	'Finally,',CR,LF
	db	'		HJELP (FILE)',CR,LF
	db	'will assume that FILE.HLP is a member of FILE.LBR. Such',CR,LF
	db	'a construction presupposes that FILE.LBR contains many',CR,LF
	db	'additional files which are referenced through FILE.HLP.',CR,LF
	db	'In all cases, an explicitly given extension will be',CR,LF
	db	'respected, even when it is different from the default.',CR,LF
	db	'$'
X0954:	db	CR,LF,'  HELP File Selections are --',CR,LF,'$'
X0976:	db	'EOI '
X097A:	db	'^C=Exit $'
X0983:	db	'^=Level .=Root $'
X0993:	db	'M=Menu S=Start L=Last P=Print $'
X09B2:	db	'Printing in Progress -- Strike ^C to Quit $'
X09DE:	db	'Please Set Top-of-Form on Printer',CR,LF
	db	'  Strike S to Print this Screen Only,'
	db	' ^C to Quit, or',CR,LF
	db	'  Any Other Char to Print Entire Information Section - $'
X0AC6:	db	CR,LF,'% -- Invalid Response',CR,LF,'$'
X0AE9:	db	CR,LF,'% -- EOF on HELP File',CR,LF,'$'
X0B4A:	db	CR,LF,'% -- Node Level Limit Reached'
	db	' -- Returning to CP/M',CR,LF,'$'
X0B81:	db	CR,LF,'% -- Invalid File Name in Load',CR,LF,'$'
X0BAD:	db	CR,LF,'% -- No Higher Level to Return to',CR,LF,'$'
X0BDC:	db	CR,LF,'% -- Not Enough Room for HELP File',CR,LF,'$'
X0C0C:	db	'Level $'
X0C13:	db	'/ $'
X0C16:	db	': $'
X0C19:	db	'Type  ^C=Exit$'
X0C27:	db	' ^=Level .=Root$'
X0C37:	db	' or Enter Selection $'
lohf:	db	CR,LF,'Loading HELP File $'
chno:	db	CR,LF,'Checksum failure.$'
nlib:	db	CR,LF,'Requested library not present.$'
rerr:	db	CR,LF,'Read error.$'
nfil:	db	CR,LF,'Requested file not present.$'

mlen:	ds	2		;length (records) of member
rlen:	ds	2		;length (32-byte lines) of directory
actr:	ds	2
aptr:	ds	2
abuf:	ds	32
nbuf:	ds	12
mctr:	ds	2
mptr:	ds	2
oper:	ds	1		;color operation
dest:	ds	1		;color area
octr:	ds	2
optr:	ds	2
obuf:	ds	80H
X0C61:	ds	1		;z/nz = panel/section (P)
X0C62:	ds	1		;user code
X0C63:	ds	1		;memory pages
X0C68:	ds	1		;option letter
X0C6B:	ds	1		;console remaining lines
X0C6E:	ds	2		;ptr end of text
X0C70:	ds	1		;z/nz = 1/2 digit number
X0C71:	ds	1		;level #
X0C72:	ds	1		;panel #
X0C73:	ds	ND*22+100	;PDL for HELP file names/stack
X0D31:	ds	2		;save stack pointer
cksm:	ds	2		;checksum
lach:	ds	1		;%; last character typed	S
rcnt:	ds	1		;%; repetition count		E
roco:	ds	1		;%; rotating bit counter	Q
roby:	ds	1		;%; rotating byte		U
dens:	ds	1		;%; z/nz=normal/squeezed file	E
wflg:	ds	1		;%; z/nz=no/byte awaiting abyt	N
wbyt:	ds	1		;%; byte left waiting by abyt	C
tptr:	ds	2		;%; text pointer		E
xptr:	ds	2		;ptr to bgn of HELP file
yptr:	ds	2		;zptr+NS
zptr:	ds	2		;ptr to bgn of info sect
cptr:	ds	2		;Huffman code table
pptr:	ds	2		;pushdown pointer
mopt:	ds	1		;maximum option
char:	ds	1		;char read from console
pudl:	ds	NS*50		;pushdown for section heads
X0D33:	ds	0		;free memory

;	Layout of pudl and pointers:
;
;		pudl:	menu
;			...
;			menu
;		zptr->	panel 1
;		yptr->	panel 2
;			...
;		pptr->	panel n
;			x
;			x
;			x
;		X0D33:	x
;			x
;		cptr->	Huffman code
;			x
;			x
;		xptr->	HELPfile text
;			x
;			x
;		tptr->	x
;			x
;			x

	end