1

我已经为 CCS V5 中的 FIR 实现编写了这段代码。

调试时

LDH  .D1 *A4,A2 ; A2=x[n-k] k=1,...,N
LDH  .D2 *B4++,B2 ; B2=h[k] k=1,...,N

这部分代码被忽略，或者说 A2 和 B2 的值保持不变。我尝试将 const 值数组赋予参数，但没有帮助。我猜它的浮点格式有一些问题。

任何帮助表示赞赏。

#include<stdio.h>
#include<stdlib.h>
#define N 4
extern FIR_asm_func();

int main()
{
    int y;//,h;
    float out;
    float x[N+1]={20,0,0,0,0};
    FILE *fip,*fop;
    char signal[]="signal";
    char output[]="output";
    float coeff[]={1,1,1,1,1};
    fip = fopen('signal',"r"); // read mode
    fop = fopen('output',"w");  // write mode
    y=201;
    while(y--)
    {
        fscanf(fip,"%f",&x[0]);
        //printf("%d\n",x[0]);
        out = FIR_asm_func(x,coeff,5);
        fprintf(fop,"%f,",out);
    }
        fclose(fip);
        fclose(fop);
        printf("End");
    return 0;
}


; FIR_asm_func.asm
; asm function called from C to implement fixed-point FIR
; A4 = x[n] address, B4 = h[0] address, A6 = filter order N
; input samples organized as x(n)...x(n-N)
; coefficients as h[0]...h[N]


        .global _FIR_asm_func

_FIR_asm_func:
        MV    .L1   A6,A1       ; setup loop count in A1
        ZERO  .S1   A8          ;   initialization  A8 for accumulation
        LDH   .D1   *A4++,A2        ;       x[n]
        LDH   .D2   *B4++,B2        ;       h[0]    
        MPY   .M1   A2,B2,A7        ; A7=x[n]*h[0]      

        ADD   .L1 A7,A8,A8          ; accumlate in A8
LOOP:
        MV   .L1 A2,A3          ; making space for newer sample
        LDH  .D1 *A4,A2 ; A2=x[n-k] k=1,...,N
        LDH  .D2 *B4++,B2 ; B2=h[k] k=1,...,N

        STH .D1 A3,*A4++ ;      
        MPY .M1 A2,B2,A7 ; A7=h[k]*x[n-k]

        ADD .L1 A7,A8,A8 ; accumulate in A8
        SUB .S1 A1,1,A1  ; decrement loop count A1

    [A1]   B    .S2   LOOP ; branch to loop if A1 # 0

        NOP 

        MV .L1 A8,A4 ; result returned in A4
        B .S2 B3 ; return addr to calling routine
        NOP 
        .end
4

0 回答 0