;-------------------------fix routine begins--------------------------+
; from BLUEBOOK OF ASSEMBLY ROUTINES FOR IBM PC & XT.
;         page : 107
;
; NAME  FIX
;
; ROUTINE FOR Conversion from Internal Floating Point to 16-Bit Integer
;
; FUNCTION: This routine converts from internal single precision binary
; floating point to internal 16-bit signed two's complement integer.
;
; INPUT: Upon entry a single precision binary floating point is in
; SFPBUFF.  The single precision floating point nu ber has a 24-bit
; binary mantissa, a sign bit, and an 8-bit exponent biased by 128.
;
; OUTPUT: Upon exit a 16-bit signed two's complement binary number
; is in the DX register.
;
; REGISTERS USED:  Only DX is modified, used for output.
;
; SEGMENTS REFERENCED:  The data segment contains storage for SFPBUFF.
;
; ROUTINES CALLED:  None
;
; SPECIAL NOTES: Equates used to shorten address fields.
;
; ROUTINE TO CONVERT FROM INTERNAL FLOATING POINT TO INTERNAL INTEGER
; (truncate).
;
fix	proc	far
;
; the number is in sfpbuff
;
	push	cx		; save registers
	push	ax
;
; get the mantissa
	mov	ax,sfpbuffw0	; AX gets the low part
	mov	dx,sfpbuffw2	; DX gets high part
	and	dx,007Fh	; just the mantissa
	or	dx,0080h	; restore MSB
;
; get the exponent
	mov	cl,sfpbuffb3	; get the exponent
	mov	ch,0		; extend to 16-bit
	sub	cx,88h		; subtract bias
	cmp	cx,0		; check its sign
	jl	fix1		; if negative
	jg	fix2		; if positive
	je	fix3		; if zero
;
fix1:
; shift right
	neg	cx		; absolute value
;
fix2:
	sar	dx,1		; shift all bits right
	rcr	ax,1		; carry on
	loop	fix2
;
	jmp	fix4		; end of case
;
fix3:
; shift left
	sal	ax,1		; shift all bits left
	rcl	dx,1		; carry on
	loop	fix3
;
	jmp	fix4		; end of case
;
fix4:
; check the sign
	mov	al,sfpbuffb2	; get sign
	and	al,80h		; just bit 7
	jz	fix5		; is it on ?
	neg	dx		; two's compl if negative
;
fix5:
;
	pop	ax		; restore registers
	pop	cx
	ret			; return
;
fix	endp
;-------------------------fix routine ends---------------------------+