PRJ: 数据波动_RMS计算

/*
 * noise.h
 * calculation tool for the sensor noise.
 *
 *  -when-      -who-      -what-
 * 2012.10.21   mars        v1.0
 */


#ifndef __NOISE_H__
#define __NOISE_H__

int cal_acc_sensor_noise(float *xyz, int cnt, float *xyz_o);
int parse_sensor_data(char *file_name, int dump_row_cnt);

endif /* __NOISE_H__ */
           

/*
 * noise.c
 * calculation tool for the sensor noise.
 *
 *  -when-      -who-      -what-
 * 2012.10.21   mars        v1.0
 */

#include "noise.h"

#include <stdio.h>
#include <malloc.h>
#include <string.h>
#include <math.h>

#define noise_debug
#ifdef noise_debug
#define debug(x,argc...)  printf(x,##argc)
#else
#define debug(x,argc...) NULL
#endif /* noise_debug */

#define COLUMN_CNT  3
int 
cal_acc_sensor_noise(float *xyz, int cnt, float *xyz_o)
{
    int i, k;
    float avg;
    float sum;
    float tmp;

    debug ("## cal variance ... \r\n");
		
    if (xyz == NULL || xyz_o == NULL) return 0;
    if (cnt < COLUMN_CNT || cnt%COLUMN_CNT) return 0;

    cnt = cnt/COLUMN_CNT;
    for (k = 0; k < COLUMN_CNT; ++k) {
			
        for (sum = 0.0, i = 0; i < cnt; ++i) { 
            sum += xyz[COLUMN_CNT*i+k]; 
        }
        avg = sum / (float)cnt;
			
        for (sum = 0.0, i = 0; i < cnt; ++i) {
            tmp = xyz[COLUMN_CNT*i+k] - avg;	
            sum += tmp * tmp;
        }
        xyz_o[k] = sqrt (sum / (float)cnt);
    }

    debug ("variance %f, %f, %f \r\n", xyz_o[0], xyz_o[1], xyz_o[2]);
    debug ("## cal variance, done. \r\n\r\n");
    return 1;
}

static int
get_file_size(FILE *f_stream) 
{ 			
    long cur;
    long size; 

    cur = ftell(f_stream);
    fseek(f_stream, 0L, SEEK_END); 
    size = ftell(f_stream); 
    fseek(f_stream, cur, SEEK_SET);
		
    return size;	 
}

int
parse_sensor_data(char *file_name, int dump_row_cnt)
{
    int i;
    int rt;
    int sz;
    char ch;
    FILE *f_stream;
    float *f_vals;
    float variance[3]; 
    const char *out_file = {"variance.txt"};
				
    debug ("##open file %s ... \r\n", file_name);
    if ((f_stream = fopen(file_name, "rb")) == NULL) {
        debug ("can not open %s \r\n", file_name);
        goto END;
    }
    debug ("##file opened, done. \r\n\r\n");

    sz = get_file_size(f_stream);
    debug ("file size %d byes\r\n", sz);
    f_vals = (float*)malloc (sz * sizeof(float));
    if (f_vals == NULL) {
    	debug ("malloc failed. \r\n");
    	goto END;
    }
    
    debug ("##dump the first %d rows ... \r\n", dump_row_cnt);
    while (dump_row_cnt > 0) {
    	rt = fread(&ch, 1, 1, f_stream); 
    	if (rt <= 0) goto END;
    	if (ch == '\n') dump_row_cnt--;
    }
    debug ("##dump the rows, done. %d \r\n\r\n");
    
    debug ("## read xyz data  with format:\"%s\" ... \r\n", "%f,%f,%f");
    memset((void*)f_vals, 0, sz * sizeof(float));
    for (i = 0; i < sz; i += 3) {
        rt = fscanf(f_stream, "%f,%f,%f", &f_vals[i], &f_vals[i+1], &f_vals[i+2]);
        if (rt != 3) break;
#if 0					
        debug ("%f, %f, %f\r\n", f_vals[i], f_vals[i+1], f_vals[i+2]);
#endif		    
    }

    if (i <= 0) goto END;
		
    debug ("xyz cnt %d \r\n", i/3);
    debug ("## read xyz data, done. \r\n\r\n");

    rt = cal_acc_sensor_noise (f_vals, i, variance);
    if (!rt) goto END;

    if (f_stream != NULL) {
    	fclose(f_stream);
    	f_stream = NULL;
    }
    
    debug ("##open file %s ... \r\n", out_file);
    if ((f_stream = fopen(out_file, "wb+")) == NULL) {
        debug ("can not open %s \r\n", out_file);
        goto END;
    }
    debug ("##file opened, done. \r\n\r\n");
    
    debug ("## write variances to %s ... \r\n", out_file);
    sz = sprintf((char*)f_vals, "%f, %f, %f \r\n", 
                  variance[0], variance[1], variance[2]);
    rt = fwrite ((char*)f_vals, 1, sz, f_stream);
    if (rt < sz) goto END;
    debug ("## write variances to %s, done. \r\n", out_file);
    	  	    
    if (f_stream != NULL) {
    	fclose(f_stream);
    	f_stream = NULL;
    }
 
    if (f_vals != NULL) {
    	free(f_vals);
    	f_vals = NULL;
    }
       
    return 1;	
END:
    if (f_stream != NULL) {
    	fclose(f_stream);
    	f_stream = NULL;
    }	

    if (f_vals != NULL) {
    	free(f_vals);
    	f_vals = NULL;
    }    
    return 0;     
}

#ifdef noise_debug

int
main(int argc, char **argv) 	
{ 	
    int rt; 
    int dump_row_cnt;  
    
    dump_row_cnt = 1;
    if (argc <= 1) goto END;
    if (argc == 3) dump_row_cnt = atoi(argv[2]);
			
    rt = parse_sensor_data (argv[1], dump_row_cnt);
    if (!rt) goto END;
		
END:    
    while (1);	
}  

#endif /* noise_debug */

           

//log.txt

[BEGIN] 2012-10-17 16:06:45

106,94,-54

109,96,-51

107,93,-52

105,94,-52

108,91,-53

106,90,-53

105,93,-53

106,91,-52

108,92,-52

107,90,-48

109,93,-54

107,91,-49

107,93,-51

108,93,-52

106,93,-51

107,92,-55

105,91,-48

107,90,-52

104,94,-49

107,90,-52

105,94,-51

104,91,-52

107,91,-49

106,93,-53

107,90,-53

103,92,-54

104,92,-53

...

// gcc

gcc noise.c -o cal_noise

//cal_noise.bat

start "debug" /D "."  "cal_noise.exe" log.txt 1

enjoy~

mars

october 21,2012

[email protected]