div_s.asm

基于TMS320F2812的AMR+RS编解码+OFDM调制解调源程序。是stand alone运行版本

***************************************************************************
** Description:     div_s() in basicop2.c                              
**                                                                         
** Inputs:                                                                  
**                                                                         
**   AR1:		Word16 var1
** 	 AR2:		Word16 var2                                               	   
**                                                                         
** Outputs:                                                                
**                                                                            
** Return value:   
** 
**	 AL:		Word16 var_out                                               
**                                                                         
** Attribute:   Cycles: 125       Pm: 17 
**
** Modified Registers:  ACC, P                          
**                                                                         
** Programmer:	Liu Yang
**
** Complete time:	2003 3 11
*****************************************************************************

	.global _div_s
	
_div_s:
		CMP		AR1,#0				; if (var1 == 0) 
		SB 		B1,NEQ
		MOV		AL,#0				; var_out = 0
		
		LRETR
		
B1:		MOV		AL,@AR1				; if (var1 == var2)
		CMP		AL,@AR2
		SB		B2,NEQ
		MOV		AL,#0x7FFF			; var_out = MAX_16
		
		LRETR

B2:		MOV		ACC,@AR1 << #15		; ACC = 0x8000 * var1
		MOVL 	P,ACC 		        ; Load P register with the numerator 0x8000 * var1
		MOVZ 	AR2,@AR2 	  		; Move denominator var2 to XAR2
		MOVB	ACC,#0      		; Clear ACC to perform the division.
		
		NOP
		NOP
		NOP
		RPT #31             
	  ||SUBCUL 	ACC,@XAR2  			; Divide numerator var1 by the denominator var2
	  								; the quotient var_out is in P and the remainder is in ACC
   		MOVL 	ACC,@P      		; Load the quotient var_out into ACC
				
		LRETR