; =============================================================================
;
;                            Litos - Text string
;
; =============================================================================


		CODE_SECTION	32

; -----------------------------------------------------------------------------
;                 Convert HEX ASCII character to number
; -----------------------------------------------------------------------------
; INPUT:	AL = HEX character ("0" to "9", "A" to "F", "a" to "f")
; OUTPUT:	AL = number 0 to 15 (if NC) or AL not changed (if CY)
;		CY = invalid HEX character (AL not changed)
; -----------------------------------------------------------------------------

; ------------- Check digit

CharHexToBin:	cmp	al,"0"		; check number MIN
		jb	CharHexToBin9	; invalid character
		cmp	al,"9"		; check number MAX
		jbe	CharHexToBin7	; character is OK

; ------------- Check capital letter

		cmp	al,"A"		; check letter MIN
		jb	CharHexToBin9	; invalid character
		cmp	al,"F"		; check letter MAX
		jbe	CharHexToBin6	; character is OK

; ------------- Check small letter

		cmp	al,"a"		; check letter MIN
		jb	CharHexToBin9	; invalid character
		cmp	al,"f"		; check letter MAX
		ja	CharHexToBin8	; invalid character

; ------------- Convert small letter to BIN (it clears CF)

		sub	al,"0"+("a"-("9"+1)) ; convert ASCII to BIN
		ret			; here is NC

; ------------- Convert capital letter to BIN (it clears CF)

CharHexToBin6:	sub	al,"0"+("A"-("9"+1)) ; convert ASCII to BIN
		ret			; here is NC

; ------------- Convert ASCII digit to BIN (it clears CF)

CharHexToBin7:	sub	al,"0"		; convert ASCII to BIN
		ret			; here is NC

; ------------- Invalid HEX character

CharHexToBin8:	stc			; set error flag
CharHexToBin9:	ret

; -----------------------------------------------------------------------------
;                   Convert ASCII digit to number
; -----------------------------------------------------------------------------
; INPUT:	AL = ASCII digit character ("0" to "9")
; OUTPUT:	AL = number 0 to 9 (if NC) or AL not changed (if CY)
;		CY = invalid digit character (AL not changed)
; -----------------------------------------------------------------------------

; ------------- Check digit

CharDigToBin:	cmp	al,"0"		; check number MIN
		jb	CharDigToBin9	; invalid character
		cmp	al,"9"		; check number MAX
		ja	CharDigToBin8	; invalid character

; ------------- Convert ASCII digit to BIN (it clears CF)

		sub	al,"0"		; convert ASCII to BIN
		ret			; here is NC

; ------------- Invalid HEX character

CharDigToBin8:	stc			; set error flag
CharDigToBin9:	ret

; -----------------------------------------------------------------------------
;                                   Data
; -----------------------------------------------------------------------------

		DATA_SECTION

; ------------- Empty texts

		align	4, db 0
EmptySText:	STEXT	''

		align	4, db 0
EmptyMText:	MTEXT	''

		align	4, db 0
EmptyLText:	LTEXT	''

		align	4, db 0
EmptyText:	TXT	''