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#include "cmd_fir1p.h"
#define FIR_SIZE 12
double fir_coef[FIR_SIZE] =
{
-0.0044384, -0.0041841, 0.0130183, 0.0746628,
0.1720210, 0.2489204, 0.2489204, 0.1720210,
0.0746628, 0.0130183, -0.0041841, -0.0044384
};
#define MAX_INPUT_LEN 80
#define BUFFER_LEN (FIR_SIZE-1+MAX_INPUT_LEN)
double insamp[BUFFER_LEN];
int fir1filter(double *coeffs, double *input, double *output,
int length, int filter_length)
{
double acc;
double *coeffp;
double *inputp;
int n;
int k;
memcpy(&insamp[filter_length-1], input, length*sizeof(double));
for (n=0; n<length; n++)
{
coeffp = coeffs;
inputp = &insamp[filter_length - 1 + n];
acc = 0;
for (k=0;k<filter_length;k++)
{
acc += (*coeffp++)*(*inputp--);
}
output[n] = acc;
}
memmove(&insamp[0], &insamp[length], (filter_length-1)*sizeof(double));
return 0;
}
void *cmd_fir1p(void *data)
{
char *ret = NULL;
int i=0,j=0;
if (data == NULL)
{
ret = alloc_new_str("FIR filter N=12\n");
return ret;
}
double input[MAX_INPUT_LEN];
double output[MAX_INPUT_LEN];
int count;
sds params = sdsnew(data);
sds out_result = sdsempty();
sds *tokens;
//printf("%s\n",params);
//tokens = sdssplitlen(params, sdslen(params), " ", 1, &count);
tokens = sdssplitargs(params, &count);
for (i=0;i<count;i++)
{
//printf("[%s]\n",tokens[i]);
input[i] = atof(tokens[i]);
}
fir1filter(fir_coef, input, output, count, FIR_SIZE);
for (i=0;i<count;i++)
{
//cut to max size 512
char str_double[16];
snprintf(str_double, 16, "%.3f ", output[i]);
out_result = sdscat(out_result, str_double);
}
out_result = sdscat(out_result,"\n");
ret = alloc_new_str(out_result);
sdsfree(params);
sdsfree(out_result);
sdsfreesplitres(tokens, count);
return ret;
}
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