RomWBW/Source/CPM3/util.z80

	title	'Utility module for RomWBW'
	
	maclib	options.lib
	
	public addhla, bcd2bin, bin2bcd
	public phex16, phex8, cout
	
	cseg

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

bcd2bin:
	; convert A from packed bcd to binary
	push	bc
	ld	c,a
	and	0F0h
	srl	a
	ld	b,a
	srl	a
	srl	a
	add	a,b
	ld	b,a
	ld	a,c
	and	0Fh
	add	a,b
	pop	bc
	ret

bin2bcd:
	; convert A from binary to packed bcd
	push	bc
	ld	b,10
	ld	c,-1
bin2bcd1:
	inc	c
	sub	b
	jr	nc,bin2bcd1
	add	a,b
	ld	b,a
	ld	a,c
	add	a,a
	add	a,a
	add	a,a
	add	a,a
	or	b
	pop	bc
	ret

	if 0
;
; Print the hex word value in HL
;
phex16:
	push	af
	ld	a,h
	call	phex8
	ld	a,l
	call	phex8
	pop	af
	ret
;
; Print the hex byte value in A
;
phex8:
	push	af
	push	de
	call	hexascii
	ld	a,d
	call	cout
	ld	a,e
	call	cout
	pop	de
	pop	af
	ret
	
;
; Convert binary value in A to ascii hex characters in DE
;
hexascii:
	ld	d,a
	call	hexconv
	ld	e,a
	ld	a,d
	rlca
	rlca
	rlca
	rlca
	call	hexconv
	ld	d,a
	ret
;
; convert low nibble of A to ascii hex
;
hexconv:
	and	0Fh	     ;low nibble only
	add	a,90h
	daa
	adc	a,40h
	daa
	ret
;
; output character from A
;
cout:
	; save all incoming registers
	push	af
	push	bc
	push	de
	push	hl
	ld	e,a
	ld	bc,0100h
	rst	08
	pop	hl
	pop	de
	pop	bc
	pop	af
	ret

	else

phex16:
phex8:
cout:
	halt
	
	endif

	end