Initialize the 80C187 Numerics Co-processor

 
$mod186
name		example_80C187_init
;
; FUNCTION:	This function initializes the 80C187 numerics
; 		co-processor.
;
; SYNTAX:	extern unsigned char far 187_init(void);
;
; INPUTS:	None
;
; OUTPUTS:	unsigned char - 0000h -> False -> coprocessor not
; initialized
;			 ffffh -> True -> coprocessor
; initialized
; NOTE:	Parameters are passed on the stack as required by
;		high-level languages.
; 
lib_80186	segment public 'code'
		assume cs:lib_80186
		public	_187_init
_187_init	proc far
		push	bp			;save caller's bp
		mov	bp, sp		;get current top of stack
		cli				;disable maskable
						;interrupts
		fninit			;init 80C187 processor
		fnstcw [bp-2]		;get current control word
		sti				;enable interrupts
		mov	ax, [bp-2]
		and	ax, 0300h		;mask off unwanted control
						;bits
		cmp	ax, 0300h		;PC bits = 11
		je	Ok			;yes: processor ok
		xor	ax, ax		;return false (80C187 not
						;ok)
		pop	bp			;restore caller's bp
		ret
	Ok:	and	[bp-2], 0fffeh	;unmask possible exceptions
		fldcw	[bp-2] 
		mov	ax,0ffffh		;return true (80C187 ok)
		pop	bp			;restore caller's bp
		ret
_187_init	endp
lib_80186	ends
		end