mul.s43

msp430心电仪程序代码 ............Heart rate ............Heart rate with DAC output ............Heart rat

//
//16x16=>32 multiply
//long mul16(register int x, register int y)
// 
// Edited by: M Morales, November 2008
// * Updated calling conventions in support of IAR compiler >= 4.x  
//*****************************************************************************
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	public mul16

	RSEG CODE
mul16

#define x1 r9
#define z0 r14
#define z1 r15
#define x  r12
#define y  r13

        push    r9

	clr	z0
	mov	z0,z1
	mov	z0,x1
	tst	x
	jge	xbooth_2
	mov	#-1,x1
	jmp	xbooth_2

xbooth_6
	add	x,z1
	addc 	x1,z0
xbooth_1
	rla	x
	rlc	x1
xbooth_2
	rra	y
	jc	xbooth_5
	jne	xbooth_1
	jmp	xbooth_4

xbooth_5
	sub	x,z1
	subc 	x1,z0
xbooth_3
	rla	x
	rlc	x1
	rra	y
	jnc	xbooth_6
	cmp	#0FFFFh,y
	jne	xbooth_3

xbooth_4
        mov     z1,r12
        mov     z0,r13
        
        pop     r9

        ret
        end