title 'general utility routines'

	; i/o port init routines

	public ioiniml,ioini1l		;

	; math

	public add_hla			; add a to hl
	public div32_16,div32_r		; divide 32 bit by 16 bit number (rounded)

	; print utils

	public ?pmsg			; print message
	public pr.inln,pr.crlf		; print message inline, print newline
	public phex2,phex4		; print 2 digit hex (A) or 4 digit hex (HL)
	public pr.dec,pr.decl		; print 16 or 32 bit decimal number
	public ?pderr			; print BIOS disk error message header



	extrn ?cono
	extrn @adrv,@trk,@sect		; used by disk error message

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

cr	equ	13
lf	equ	10
bell	equ	7


	dseg

;----------------------------------------------------------------------
; output bytes to consecutive portaddresses
;
;     hl: table with following structure:
;        db n, port1, val1, val2,... valn
;        db m, port1, val1, val2,... valm
;        ...
;        db 0 ; Terminate table

ioiniml:
	push	bc
	xor	a
ioml_lp:
	ld	b,(hl)
	inc	hl
	cp	b
	jr	z,ioml_e

	ld	c,(hl)
	inc	hl
	otimr
	jr	ioml_lp
ioml_e:
	pop	bc
	ret

;----------------------------------------------------------------------
; output bytes to ports
;
;     hl: tables of port,value pairs:
;         db n, port1,val1, port2,val2,... portn,valn
;         ...
;         db 0 ; Terminate table

ioini1l:
	push	bc
	jr	io1_nxt
io1_lp:
	ld	c,(hl)		;port address
	inc	hl
	otim
	jr	nz,io1_lp
io1_nxt:
	ld	b,(hl)		;count
	inc	hl
	inc	b
	djnz	io1_lp

	pop	bc
	ret

;--------------------------------------------------------------------
; add a to hl
;
;    return:
;       hl = hl + a
;       Flags undefined

add_hla:
	add	a,l
	ld	l,a
	ret	nc
	inc	h
	ret

;--------------------------------------------------------------------
; rounded div 32 by 16 bit
;
;	HLDE:	Dividend (x)
;	BC:	Divisor  (y)
;    return:
;	HLDE: 	Rounded Quotient (q)
;	BC:   	Remainder	       (r)

div32_r:
	push bc
	srl	b		;y/2
	rr	c
	add	hl,bc		;low x + y/2
	pop	bc
	jr	nc,div_r1
	inc	de
div_r1:
	;fall thru

;--------------------------------------------------------------------
; Divide 32 bit by 16
;
;    DEHL:	Dividend (x)
;    BC:	Divisor  (y)
;
;  return:
;    DEHL:	Quotient
;    BC:	Reminder

div32_16:
	exx			;low
	push	de		;save alternate registers (de,bc)
	push	bc
	exx			;high
	push	hl		;lx
	push	bc		;ly
	ld	bc,0		;bc  = hy = 0
	ld	h,b		;hl  = hr = 0
	ld	l,c
				;de = x, hl = r
	exx			;low
	pop	bc		;bc' = ly
	ex	(sp),hl		;hl' = lx, save alternate hl
	ld	de,0		;de' = lr = 0
	ex	de,hl		;de = x, hl = r
	exx			;high
	ld	a,32		;count
;
; start:
;     de: x	(de: hx, de': lx)
;     bc: y	(bc: hy, bc': ly)
;     hl: 0
;
div_lp:				;do
	exx			;    low
	ex	de,hl		;    x
	add	hl,hl		;    x <<= 1
	exx			;    high
	ex	de,hl		;    x
	adc	hl,hl		;    x <<= 1
	exx			;    low
	ex	de,hl		;    r
	adc	hl,hl		;    r <<= 1
	exx			;    high
	ex	de,hl		;    r
	adc	hl,hl		;    r <<= 1
	exx			;    low
	inc	de		;    x/q += 1
	or	a		;
	sbc	hl,bc		;
	exx			;    high
	sbc	hl,bc		;
	jr	nc,div_no_restore
	exx			;        low
	dec	de		;
	add	hl,bc		;        r += y
	exx			;        high
	adc	hl,bc		;

div_no_restore:			;
	dec	a		;
	jr	nz,div_lp	;while (--count)

; result:
;     de: q	(de: hq, de': lq)
;     hl: r	(hl: hr, hl': lr)

	exx			;low
	ex	de,hl		;hl = lq,  de = lr

	ex	(sp),hl		;lq
	push	de		;lr
	exx			;high
	pop	bc		;bc = lr
	pop	hl		;de = lq

	exx			;low
	pop	bc		;restore alternate registers
	pop	de
	exx			;high
	ret

;-------------------------------------------------------------------------------
; print message @<HL> up to a null
; saves <BC> & <DE>

?pmsg:
	push	bc
	push	de
pmsg$loop:
	ld	a,(hl)
	or	a
	jr	z,pmsg$exit
	ld	c,a
	push	hl
	call	?cono
	pop	hl
	inc	hl
	jr	pmsg$loop
pmsg$exit:
	pop	de
	pop	bc
	ret

;-------------------------------------------------------------------------------
; print message inline up to a null
; saves all registers

pr.inln:
	ex	(sp),hl
	push	af
	call	?pmsg
	pop	af
	ex	(sp),hl
	ret

;-------------------------------------------------------------------------------
; print <CR><LF>
; saves all registers

pr.crlf:
	call	pr.inln
	db	cr,lf,0
	ret

;-------------------------------------------------------------------------------
; print hl as a 4 digit hexadecimal number
; saves all registers

phex4:
	ld a,h
	call phex2
	ld a,l
	; fall thru

;-------------------------------------------------------------------------------
; print a as a 2 digit hexadecimal number
; saves all registers

phex2:
	push	af
	rra
	rra
	rra
	rra
	call	print.digit
	pop	af

print.digit:
	push	hl
	push	de
	push	bc
	push	af
	and	00fh
	cp	10
	jr	c,prd_1
	add	a,007h
prd_1:
	add	a,'0'

	ld	c,a
	call	?cono
	pop	af
	pop	bc
	pop	de
	pop	hl
	ret


;-------------------------------------------------------------------------------
; print decimal 16 bit number from HL
;
;	HL: unsigned binary number to print
;	 C: minimum print field width
;	    number is prined right-aligned
;	 B: pad character, typically ' ' or '0'

pr.dec:
	push	de
	ld	de,0
	call	pr.decl
	pop	de
	ret

;-------------------------------------------------------------------------------
; print decimal 32 bit number from DEHL
;
;	DEHL: unsigned binary number to print
;	   C: minimum print field width
;	      number is prined right-aligned
;	   B: pad character, typically ' ' or '0'

pr.decl:
	push	bc		;save width and fillchar
	push	bc
	exx			;(alt)
	ex	(sp),hl		;save hl', get width and fill
	push	de		;save de'

	xor	a
	ld	d,a		;clear counter
	ld	e,a
	push	af		; string terminator
	inc	sp

prd_divloop:			;do
	exx			;    (main)
	ld	bc,10		;
	call	div32_16	;    get a digit
	ld	a,c		;
	add	a,'0'		;    make it printable
	push	af		;

	ld	a,h		;
	or	l		;
	or	d		;
	or	e		;
	exx			;    (alt)
	inc	sp		;
	inc	de		;
	jr	nz,prd_divloop	;

prd_filloop:			;h=filler, l=field width
	ld	a,e
	cp	l
	jr	nc,prd_out
	push	hl
	inc	sp
	inc	de
	jr	prd_filloop
prd_out:
	ld	hl,0
	add	hl,sp		;ptr to beginning of number string (hl==0 here)
	call	?pmsg
	ex	de,hl
	add	hl,sp
	ld	sp,hl
	inc	sp		;remove string terminator
	pop	de
	pop	hl
	exx			;(main)
	pop	bc
	ret


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

?pderr:
	ld	hl,drive$msg
	call	?pmsg		; error header
	ld	a,(@adrv)
	add	a,'A'
	ld	c,a
	call	?cono		; drive code
	ld	hl,track$msg
	call	?pmsg		; track header
	ld	c,0
	ld	hl,(@trk)
	call	pr.dec		; track number
	ld	hl,sector$msg
	call	?pmsg		; sector header
	ld	hl,(@sect)
	call	pr.dec		; sector number
	ret

	; error message components
drive$msg:	db	cr,lf,bell,'BIOS Error on ',0
track$msg:	db	': T-',0
sector$msg:	db	', S-',0