lab5.asm

利用CCS实现IIR滤波器的功能

**********************************************
* LENGTH-80 LINEAR-PHASE PASSBAND FIR FILTER *  
**********************************************
        
        .title  "lab5.asm"

        .mmregs
        .def    start
        .bss    y,1
x_new   .usect  "DATA1",4
x_old   .usect  "DATA2",4
size    .set    4
PA0     .set  0
PA1     .set  1

        .data        
COEF   .word   0ffdch,0001fh
       .word   0ffbah,0ffb4h
       

        .text
start:  LD      #y,DP
        SSBX    FRCT
        STM     #x_new,AR2
        STM     #x_old+(size-1),AR3
        STM     #size,BK
        STM     #-1,AR0
        PORTR   PA1,*AR2
FIR     ADD     *AR2+0%,*AR3+0%,A
        RPTZ    B,#(size-1)
        FIRS    *AR2+0%,*AR3+0%,COEF
        STH     B,@y
        PORTW   @y,PA0
        MAR     *+AR2(2)%
        MAR     *AR3+%
        MVDD    *AR2,*AR3+0%
        BD      FIR
        PORTR   PA1,*AR2
        .END