1 /*----------------------------------------------------------------------------------------------------
  2 ----------------------------------------------------------------------------------------------------*/
  3 #define FFTN 512
  4 int MC_bg_cnt_wid=6; //背景单元个数.
  5 #define MC_bg_prot_wid 3 //背景保护单元个数.
  6 float dbuf[FFTN]={0.0};
  7 
  8 typedef struct{
  9     int cursn;
 10     float lsum;//left sum val;
 11     float rsum;//right sum val;
 12 }ST_BG;
 13 ST_BG g_bg={0, 0.0, 0.0};
 14 
 15 /*----------------------------------------------------------------------------------------------------
 16 使用新的方法计算背景噪声.
 17 ----------------------------------------------------------------------------------------------------*/
 18 float ComputeBg(int sn, float *datain)
 19 {
 20     int i, j, k, cursn, index;
 21     float ret;
 22     
 23     if(sn >= FFTN)
 24     {    return 0.0; // err!
 25     }
 26     if(0 == sn)
 27     {
 28         g_bg.cursn = 0;
 29         g_bg.lsum = 0.0;
 30         g_bg.rsum = 0.0;
 31         
 32         for(i=1; i<=MC_bg_cnt_wid; i++)
 33         {
 34             g_bg.rsum += datain[MC_bg_prot_wid+i];
 35         }
 36     }
 37 
 38     while(g_bg.cursn < sn)
 39     {
 40         cursn = g_bg.cursn+1;
 41         
 42         index = cursn-MC_bg_prot_wid-MC_bg_cnt_wid-1;
 43         if(index>=0)
 44         {    g_bg.lsum -= datain[index];
 45         }
 46 
 47         index = cursn-MC_bg_prot_wid-1;
 48         if((index<FFTN)&&(index>=0))
 49         {    g_bg.lsum += datain[index];
 50         }
 51 
 52         index = cursn+MC_bg_prot_wid;
 53         if(index < FFTN)
 54         {    g_bg.rsum -= datain[cursn+MC_bg_prot_wid];
 55         }
 56 
 57         index = cursn+MC_bg_prot_wid+MC_bg_cnt_wid;
 58         if(index < FFTN)
 59         {    g_bg.rsum += datain[index];
 60         }
 61         g_bg.cursn ++;
 62 }
 63     
 64     if(sn < MC_bg_prot_wid+MC_bg_cnt_wid)
 65     {//关注数据点较小,仅取右侧噪声.
 66         ret = g_bg.rsum/MC_bg_cnt_wid;
 67     }
 68     else if(sn < FFTN-(MC_bg_prot_wid+MC_bg_cnt_wid))
 69     {
 70         ret = (g_bg.lsum+g_bg.rsum)/(2*MC_bg_cnt_wid);
 71     }
 72     else if(sn < FFTN)
 73     {//关注数据点较大,仅取左侧噪声.
 74         ret = g_bg.lsum/MC_bg_cnt_wid;
 75     }
 76     else 
 77     {    ret = 0.0;
 78     }
 79     return ret;
 80 }
 81 
 82 /*----------------------------------------------------------------------------------------------------
 83 使用旧的方式计算背景噪声.
 84 ----------------------------------------------------------------------------------------------------*/
 85 float ComputeBg_old(int sn, float *datain)
 86 {
 87     int i, j, k;
 88     float lsum=0.0, rsum=0.0;
 89     float ret;
 90     
 91     if(sn >= FFTN)
 92     {
 93         return 0.0; // err!
 94     }
 95 
 96     if(sn < MC_bg_prot_wid+MC_bg_cnt_wid)
 97     {//仅计算右侧背景噪声.
 98         for(i=0; i<MC_bg_cnt_wid; i++)
 99         {
100             rsum += datain[sn+MC_bg_prot_wid+i+1];
101         }
102         ret = g_bg.rsum/MC_bg_cnt_wid;
103     }
104     else if(sn < FFTN-(MC_bg_prot_wid+MC_bg_cnt_wid))
105     {
106         for(i=0; i<MC_bg_cnt_wid; i++)
107         {
108             rsum += datain[sn+MC_bg_prot_wid+i+1];
109             lsum += datain[sn-MC_bg_prot_wid-MC_bg_cnt_wid+i];
110         }
111         ret = (lsum+rsum)/(2*MC_bg_cnt_wid);
112     }
113     else if(sn < FFTN)
114     {//仅计算左侧背景噪声.
115         for(i=0; i<MC_bg_cnt_wid; i++)
116         {
117             lsum += datain[sn-MC_bg_prot_wid-MC_bg_cnt_wid+i];
118         }
119         ret = (lsum)/(MC_bg_cnt_wid);
120     }
121     else 
122     {    ret = 0.0;
123     }
124     return ret;
125 }
126 #define REDOTIMES 10000 //重复执行次数.
127 /*----------------------------------------------------------------------------------------------------
128 ----------------------------------------------------------------------------------------------------*/
129 void CTestvc1Dlg::OnBnClickedButton1()
130 {
131     int i, j, k=0;
132     float fv, fv2;
133     long timespan;
134     time_t time0,time1, time2;
135 
136     UpdateData(true);//MFC工程更新输入的变量
137     MC_bg_cnt_wid = m_edit_bg_cnt;//用户通过MFC编辑框指定背景单元个数.
138 
139     time0 = GetTickCount();
140     srand(time0&0xffff); //随机数种子
141     for(i=0; i<FFTN; i++)
142     {
143         dbuf[i] = ((float)rand())/100.0;//获取随机数.
144     }
145     time0 = GetTickCount();
146     for(j=0; j<REDOTIMES; j++)
147     {
148         for(i=0; i<FFTN; i++)
149         {
150             fv = ComputeBg(i, dbuf); //使用新方法计算背景噪声.
151         }
152     }
153     time1 = GetTickCount();
154     for(j=0; j<REDOTIMES; j++)
155     {
156         for(i=0; i<FFTN; i++)
157         {
158             fv2 = ComputeBg_old(i, dbuf);//使用旧方法计算背景噪声.
159         }
160     }
161     time2 = GetTickCount();
162 m_edit_new_time = (long)(time1-time0);//新方法耗时时长.
163     m_edit_old_time = (long)(time2-time1);//旧方法耗时时长.
164     fv  = ((float)(time1-time0))/((float)(time2-time1));
165     m_edit_n = (int)(fv*100);//新方法耗时相对于旧方法的百分比.
166     m_edit_cnt++;
167     UpdateData(false);
168 }