根据脉搏电压数据检测心跳的程序

cal-heart.c

/* ifqqfi在gmail.com
 * [2013-07-05 五]
 *
 * 脉搏检测程序

 */

#include <stdio.h>
#include <stdlib.h>

/* 临时这个么搞，读数据的缓冲区大小 */
#define MAX_LEN  999999
/* 每秒采样次数,根据实际系统的采样率调整 */
#define SCAN_FREQ  78
/* 快速射血期 的扫描次数 */
#define QUICK_BLOOD_INJECT  ((int)(SCAN_FREQ * 0.11)) 
/* 检测到一次之后的跳跃点数 */
#define JUMP_INTERVAL   ((int)(SCAN_FREQ * 0.382)) 
/* 过滤用的门限值 */
#define THRESH_RATE   (float)(1 - 0.618)

#define DBG_SW 1
#ifdef DBG_SW
int cnt_diff_under = 0;
int cnt_range_under = 0;
#endif


/* 读取文件的buff */
float alldata[MAX_LEN];

int inline is_diff_peak(float *diff, int pos, float thr_max)
{
    float tmp;
    float *iter;
    int i;

    if (*(diff + pos) < thr_max) {
#ifdef DBG_SW
        cnt_diff_under++;
#endif
        return 0;
    }
    
    iter = diff + pos - (int)(QUICK_BLOOD_INJECT / 2);
    tmp = 0;
    for (i = 0; i < QUICK_BLOOD_INJECT; ++i, ++iter) {
        tmp += *iter;
    }

    tmp /= QUICK_BLOOD_INJECT;
    if (tmp < thr_max) {
#ifdef DBG_SW
        //printf ("pos =%d, tmp = %f\n", pos, tmp);
        cnt_range_under++;
#endif
        return 0;
    }

    return 1;
}
/* http://ifq.github.io */
int rhythmcount(float *fifo , int len)

{

    int i;

    float *diff;                /* 导数缓冲区 */
    float dif_max=0;            /* 导数最大值 */
    float thr_max;              /* 导数阀值 */
    int  j=0;
    int k[1000];                /* 用于存放最大值位置，有多少心跳次数就用多少 */

    int rhythm;
    float DR_R;                 /* 心跳间隔的采样点数品均值 */

    //printf ("len = %d\n", len);
    diff = malloc(sizeof(float) * (len+2));
    if (!diff) {
        perror("malloc fail\n");
        return (-1);
    }

    *diff=0;                    /* 头两个字节置0 */
    *(diff+1)=0;

    /* 按DIFF(i)=f(i+1)-f(i-1)+2*f(i+2)-2*f(i-2)公式计算导数 */
    for (i=2;i<len-2;i++)               
    {
        *(diff+i) = (*(fifo+i+1)) + 2 * (*(fifo+i+2))
            - (*(fifo+i-1)) - 2 * (*(fifo+i-2));

        if ((dif_max) < *(diff+i)) {
            dif_max=*(diff+i);
        }
    }

    *(diff+len-1)=0;            /* 置0 */
    *(diff+len)=0;

    thr_max=dif_max * THRESH_RATE;       //设定阈值
    
#ifdef DBG_SW
    printf ("max dif=%f, thr=%f\n", dif_max, thr_max);
#endif
    /* 检测 */
    for (i = 1; i < len - 2; i++)
    {
        if (is_diff_peak(diff, i, thr_max)) {
            k[j++]=i;
            i += JUMP_INTERVAL;
        }
    }

    DR_R=(k[j-1]-k[0])/(float)(j-1);                //计?算?R-R间?距¨¤
    printf ("dr_r %f, j=%d, gap=%d \n", DR_R, j, k[j-1]-k[0]);
    rhythm=(len/DR_R);      //通ª¡§过y公?式º?200*60/DR-R求¨®得Ì?心?率¨º值¦Ì

    free(diff);
    return rhythm;

}

/* ifqqfi */
int main(int argc, char **argv)
{
    float tmp;
    int reallen = 0;
    int totlebeat;
    float time;
    
    if (argc < 3) {
        printf ("argc not enough!\n");
        exit(-1);
    }

    time = atof(argv[2]);
    
    FILE *fp = fopen(argv[1],"r");

    while (fscanf(fp, "%f", &tmp) != EOF) {
        alldata[reallen++] = tmp > 255 ? 255 : tmp;
    }

    fclose(fp);
#if 0 
    for (i = 0; i < reallen; ++i) {
        printf ("%f\n", alldata[i]);
    }
#endif
    totlebeat = rhythmcount(alldata, reallen);

#ifdef DBG_SW
    printf("dbg diff=%d, range=%d\n",cnt_diff_under, cnt_range_under);
#endif
    /* http://iwood.co.nr */
    printf("total beat = %d, rate = %f\n", totlebeat, totlebeat/time);

    return 0;
}