单片机双字节乘法

;*********************************************************************************
;NAME: DoubleMULDouble
;INPUT:        
;FUNCTION: Ë«×ֽڳ˷¨
;DESCRIBE:          (R1:R0)*(R3:R2 )-->(R7:R6:R1:R0 )
;         
;CALL SUBPROGRAM:                                        
;USING RESOURCE:
;STACK NEED:
;OUTPUT:
;ROM SIZE:
;*********************************************************************************
 DoubleMULDouble:
               clr             R7           
               clr             R6
               mov             a,#010h         
               mov             temp0,a
               b0bclr          fc    
               rrcm            R1
               rrcm            R0                  
mul_r1:               
               b0bts1          fc                 
               jmp             mul_r2       
               mov             a,R2
               add             R6,a 
               b0bts0          fc
               incms             R7
               nop
               b0bts0          fc
               jmp             mul_r0