;-------------------------fpin begins--------------------------+
; from BLUEBOOK OF ASSEMBLY ROUTINES FOR IBM PC & XT.
;         page : 88
;
; NAME FPIN
;
; ROUTINE FOR CONVERSION FROM EXTERNAL TO INTERNAL FLOATING POINT
;
; FUNCTION: This routine accepts an ASCII decimal floating point number
; from a std input device and converts it to internal binary floating
; point.
;
; INPUT: The characters of the floating point number are received in ASCII
; through a call to a std input routine.  The decimal floating point number
; has an optional sign, followed by decimal digits of the mantissa with one
; embedded decimal point.  Following the mantissa is an optional exponent
; which starts with the letter 'E', then an optional sign, then a decimal
; number.  It is possible to get erroneous results if the number is too
; large or small to be stored as a single precision binary floating point
; number.
;
; OUTPUT: Upon exit a single precision binary floating point number is in
; SFPBUFF.  The single precision floating point number has a 24-bit binary
; mantissa, a sign bit, and an 8-bit exponent biased by 128.
;
; REGISTERS USED:  No registers are modified.
;
; SEGMENTS REFERENCED:  The data segment contains the variables FPTEMP1,
; FPTEMP2, and SFPBUFF.
;
; ROUTINES CALLED:  STDIN, FPINDIGT, FPTMUL, FPTDIV and FPTNORM
;
; SPECIAL NOTES: Equates are used to shorten address fields.
;
; ROUTINE TO CONVERT FROM ASCII EXTERNAL TO INTERNAL FLOATING POINT
;
fpin	proc	far
;
	push	di		; save registers
	push	si
	push	dx
	push	cx
	push	ax
;
; clear fp temp1 buffer
	lea	di,fptemp1	; point to fptemp1
	mov	al,0		; digit = 0
	call	fpindigt	; store digit
;
; clear the decimal flap and the count
	mov	decflag,0	; clear the flag
	mov	decexp,0	; clear the decimal exponent
;
; look for the sign
	call 	stdin		; look for sign
	cmp	al,'-'		; minus ?
	jz	fpin1		; store it
	cmp	al,'+'		; plus ?
	jz	fpin2		; ignore it
	jmp	fpin3		; anything else is a player
;
fpin1:
; set sign as a negative
	mov	fptemp1b10,80h	; put sign in place
;
fpin2:
	call	stdin		; get next digit
;
fpin3:
	cmp	al,'.'		; check for decimal point
	jne	fpin4		; press on if not
;
; set decimal flag
	cmp	decflag,0	; decimal flag already set ?
	jne	fpin5		; exit if not the first
	mov	decflag,0FFh	; set it now.
	jmp	fpin2		; go back for a digit
;
fpin4:
	sub	al,30h		; bring down from ASCII
	jl	fpin5		; too low ?
	cmp	al,9
	jg	fpin5		; too high ?
	jmp	fpin6		; got a digit
;
fpin5:
	jmp	fpin15		; end of mantissa
;
; load digit as a floating point number
fpin6:
	lea	di,fptemp2	; point to fptemp2
	call	fpindigt	; put in the digit
;
; multiply result by 10
	lea	di,fptemp1	; point to fptemp1
	call	fptmul		; multiply by 10
;
; pick one with a larger exponent
	mov	cx,fptemp1w11	; get sign of fptemp1
	sub	cx,fptemp2w11	; subtract sign of fptemp2
	je	fpin11		; skip if equal
	jg	fpin9		; if exponent fptemp2 is less
;
fpin7:
; shift the bits
	sar	fptemp1w8,1	; shift all bits right
	rcr	fptemp1w6,1	; carry on
	rcr	fptemp1w4,1
	rcr	fptemp1w2,1
	rcr	fptemp1w0,1
	loop	fpin8
;
; set the exponent
	mov	ax,fptemp2w11	; get exponent of fptemp2
	mov	fptemp1w11,ax	; put in exponent of fptemp1
;
	jmp	fpin11		; done withthis case
;
fpin9:
;
; exponent of fptemp2 is less than exp of fptemp1
;
fpin10:
; shift the bits
	sar	fptemp2w8,1	; shift all bits right
	rcr	fptemp2w6,1	; carry on
	rcr	fptemp2w4,1
	rcr	fptemp2w2,1
	rcr	fptemp2w0,1
	loop	fpin10
;
; set the exponent
	mov	ax,fptemp1w11	; get exp of fptemp1
	mov	fptemp2w11,ax	; put in exp of fptemp2
	jmp	fpin11		; end of this case
;
fpin11:
;
; add the digit to result
;
	mov	cx,5		; for a count of 5 words
	lea	di,fptemp1	; di points to fptemp1
	lea	si,fptemp2	; si points to fptemp2
	clc
;
fpin12:
	mov	ax,[si]		; get 16-bit digit from fptemp1
	inc	si		; point to next 16-bit digit
	inc	si
	adc	[di],ax		; add to 16-bit digit of fptemp2
	inc	di		; point to next 16-bit digit
	inc	di
	loop	fpin12
;
; normalize
	lea	di,fptemp1	; point to fptemp1
	call	fptnorm		; renormalize it
;
fpin13:
;
; decrement decimal exponent if dec flag is on
	cmp	deflag,0	; check decimal flag
	je	fpin14		; skip if not set
	dec	decexp		; dec exponent if set
;
fpin14:
; adjust for the decimal point
	add	al,30h		; restore ASCII
	and	al,5Fh		; upper or lower case
	cmp	al,'E'		; is it E for Exponent ?
	jne	fpin16
;
; grab exponent
;
	call	sgnd16in	; get signed decimal exponent
	add	dexexp,dx	; add it to our current value
;
fpin16:
; check for sign of decimal exponent
	mov	cx,decexp	; get decimal exponent
	cmp	cx,0		; check its sign
	jg	fpin17		; if positive
	jl	fpin18		; if negative
;
; zero count
	jmp	fpin20		; done if exponent is zero
;
; positive decimal exponent
fpin17:
	push	cx		; save count = decimal exponent
;
; multiply result by 10
	lea	di,fptemp1	; point to fptemp1
	call	fptmul		; multiply by 10
;
; normalize
	lea	di,fptemp1	; point to fptemp1
	call	fptnorm		; renormalize it
;
	pop	cx		; restore the count
	loop	fpin17
;
	jmp	fpin20		; end of this case
;
fpin18:
; negative count
	neg	cx		; absolute value of exponent
fpin19:
	push	cx		; save count
;
; divide mantissa by 10
	lea	di,fptemp1	; point to fptemp1
	call	fptdiv		; divide by 10
;
; normalize
	lea	di,fptemp1	; point to fptemp1
	call	fptnorm		; renormalize it
;
	pop	cx		; restore count
	loop	fpin19
;
fpin20:
	call	tfp2sfp		; convert to single precision
;
	pop	ax		; restore registers
	pop	cx
	pop	dx
	pop	si
	pop	di

;
	ret			; return
;
fpin	endp
;-------------------------fpin ends---------------------------+