diir.asm

《DSP原理及应用》配套源代码

			.title		"diir1.asm"
			.mmregs
			.global  start
			.def  	 start,_c_int00
N			.set     6    	
			.copy	 "IIRIN.inc"     ;输入信号x(n)数据
table								 ;IIR滤波器系数
			
			.word  63
		.word  0
		.word  -188
		.word  0
		.word  188
		.word  0
		.word  -63
		.word  0
		.word  +11675
		.word  0
		.word  +9663
		.word  0
		.word  +2948
		
			.data 
BN			.usect	 "BN",N+1
AN			.usect	 "AN",N+1
INBUF  		.usect	 "INBUF",256      ;输入缓冲区在数据区0x2400
OUTPUT		.usect	 "OUTPUT",256     ;输出缓冲区在数据区0x2600
       		.text 
        	.asg	AR0,INDEX_P
			.asg	AR2,XN_P
			.asg	AR3,ACOFF_P
			.asg	AR4,YN_P
			.asg	AR5,BCOFF_P	 
_c_int00
			b start 
			nop
			nop
start:  	SSBX	FRCT
			SSBX 	OVM
			SSBX 	SXM 				
			STM		#BN+N,AR1			
			RPT		#N
			MVPD	#table,*AR1-  		;将bi由程序区存放到数据区
			STM		#AN+N-1,AR1
			RPT		#N-1
			MVPD	#table+N+1,*AR1- 	;将ai由程序区存放到数据区
			STM		#OUTPUT,AR1
			RPTZ	A,#255
			STL	    A,*AR1+ 			;输出数据缓冲区清零
			STM		#INBUF,AR1
			RPT		#255
			MVPD	#INPUT,*AR1+		;将输入数据由程序区存放到数据区
			STM		#OUTPUT,YN_P 
			STM		#INBUF,XN_P			
			STM		#N-1,INDEX_P		

			STM		#255,BRC
			RPTB	LOOP-1		

IIR:		SUB     A,A
			STM		#BN,BCOFF_P
			STM		#AN,ACOFF_P		 			    	   	
			RPT     #N-1                ;计算前向通道
			MAC		*XN_P+,*BCOFF_P+,A 
			MAC		*XN_P, *BCOFF_P,A 
			MAR     *XN_P-0 	        ;将AR2指针指向x(n-N)     	
			RPT   	#N-1				;计算反馈通道
			MAC		*YN_P+,*ACOFF_P+,A
			STH		A,*YN_P-0           ;;保存y(n) 		
LOOP:
EEND		B 	EEND
			
 			.end