cvsd.c

TMS320C6713的16kCVSD编解码

#include<stdio.h>
#include<math.h>
//#include<c55.h>
#define BUFFERSIZEOUT 254
#define BUFFERSIZEIN  4064

//设置Delta的初始值
#define DeltaMax 1280 //台阶最大值
#define DeltaMin 6.5  //台阶最小值
#define Beta 0.99     //设置Betade的初始值
#define G1 0.509245
#define G2 1.509245
#define G3 1.509245

#define a1 0.9844964
#define b1 1.270821
#define b2 -0.320194
#define c1 -0.320194

#define ORD 6         //滤波器阶数，可以改变滤波器的阶数
#define MAX_BITS 16

int j=0;
int m=0;

double ValPreCVSD[3]={0,0,0};
double DeltaCVSD[2]={20}; //500//台阶
double Delta0CVSD=10; //500//台阶变化量
char ThreeJudgeCVSD[3]={0,1,0};
double ValPreCVSDDE[3]={0,0,0};
double DeltaCVSDDE[3]={20};//500
double Delta0CVSDDE=10;//500
char ThreeJudgeCVSDDE[3]={0,1,0};

//static double CoefA[ORD]={1.0000e+000,1.9652e+004,8.9181e+008,1.2193e+013,1.9200e+017,1.4938e+021};//{1.000000,19652, 891810000,     12193000000000,192000000000000000,1493800000000000000000}; //{1.00000000,-3.88893329,6.64074495,-6.08600100,2.98673653,-0.62768820};
//static double CoefB[ORD]={0.0000e+000,2.9369e+003,1.2847e-008,4.3301e+012,1.5947e+001,1.4938e+021};//{0,       2936.9,0.000000012847,4330100000000, 15.947,            1493800000000000000000}; //{0.03285030,-0.05723916,0.03681835,0.03681835,-0.05723916,0.03285030};
//3.4kHz 3.8kHz 30dB
static double CoefA[ORD]={1.0000e+000,
1.9655e+004,
8.8284e+008,
1.1951e+013,
1.8698e+017,
1.3938e+021};
static double CoefB[ORD]={0.0000e+000,
2.4856e+003,
-4.6812e-008,
3.8630e+012,
-3.8385e+001,
1.3938e+021};

static short filterY[ORD];
static short filterX[ORD];
char CVSDCoder(short InData);
short CVSDDecoder(char InData);

char CVSDCoder(short InData)//编码子程序
{
 double Diff=0;
 char OutData;
 Diff=InData-ValPreCVSD[1];
 
 //将输入信号用一个比特表示
 if(Diff>0) 
 { ThreeJudgeCVSD[j]=1;
   OutData=1;
 }
 else
 {
   ThreeJudgeCVSD[j]=0;
   OutData=0;
 }
 
 //三连码检测
 if(((ThreeJudgeCVSD[0]==1)&(ThreeJudgeCVSD[1]==1)&(ThreeJudgeCVSD[2]==1))|
    ((ThreeJudgeCVSD[0]==0)&(ThreeJudgeCVSD[1]==0)&(ThreeJudgeCVSD[2]==0)))
    
    DeltaCVSD[1]=a1*DeltaCVSD[0]+G1*Delta0CVSD;//若有三连码提高台阶
 else
    DeltaCVSD[1]=a1*DeltaCVSD[0];//若没有三连码将台阶变为原来的0.99倍
 if(DeltaCVSD[1]>DeltaMax)  
  DeltaCVSD[1]=DeltaMax;//台阶大于最大值,则将其还原为最大值
 if(DeltaCVSD[1]<DeltaMin)  
  DeltaCVSD[1]=DeltaMin;//台阶小于最小值,则将其还原为最小值
 DeltaCVSD[0]=DeltaCVSD[1];
 //积分器
 if(ThreeJudgeCVSD[j]==1) 
 {
 ValPreCVSD[2]=b1*ValPreCVSD[1]+b2*ValPreCVSD[0]+G2*(DeltaCVSD[1]+7.7)+G2*G1*(DeltaCVSD[0]+7.7);
 }
 if(ThreeJudgeCVSD[j]==0) 
 {ValPreCVSD[2]=b1*ValPreCVSD[1]+b2*ValPreCVSD[0]-G2*(DeltaCVSD[1]+7.7)-G2*G1*(DeltaCVSD[0]+7.7);}
 ValPreCVSD[0]=ValPreCVSD[1];
 ValPreCVSD[1]=ValPreCVSD[2];
 
 j++;
 j%=3;
 return OutData;
}

short CVSDDecoder(char InData)  //解码子程序
{
  double Max;
  int j=0;
  short OutData;
  short DataDecode;
  
  //将输入信号用一个比特表示
  if(InData==0) ThreeJudgeCVSDDE[m]=0;
  if(InData==1) ThreeJudgeCVSDDE[m]=1;
  
  //判断三连码
  if(((ThreeJudgeCVSDDE[0]==1)&(ThreeJudgeCVSDDE[1]==1)&(ThreeJudgeCVSDDE[2]==1))|
    ((ThreeJudgeCVSDDE[0]==0)&(ThreeJudgeCVSDDE[1]==0)&(ThreeJudgeCVSDDE[2]==0)))
    
   DeltaCVSDDE[1]=a1*DeltaCVSDDE[0]+G1*Delta0CVSDDE;//若有三连码提高台阶
  else
    DeltaCVSDDE[1]=a1*DeltaCVSDDE[0];//若没有三连码将台阶变为原来的0.99倍
  if(DeltaCVSDDE[1]>DeltaMax)  DeltaCVSDDE[1]=DeltaMax;//台阶大于最大值,则将其还原为最大值
  if(DeltaCVSDDE[1]<DeltaMin)  DeltaCVSDDE[1]=DeltaMin;//台阶小于最小值,则将其还原为最小值
  DeltaCVSDDE[0]=DeltaCVSDDE[1];
  //积分器
  if(ThreeJudgeCVSDDE[m]==1) {ValPreCVSDDE[2]=b1*ValPreCVSDDE[1]+b2*ValPreCVSDDE[0]+G3*DeltaCVSDDE[1]+G3*7.7;}
  if(ThreeJudgeCVSDDE[m]==0) {ValPreCVSDDE[2]=b1*ValPreCVSDDE[1]+b2*ValPreCVSDDE[0]-G3*DeltaCVSDDE[1]-G3*7.7;}
  if(ValPreCVSDDE[2]>2674) ValPreCVSDDE[2]=2674;//32767;
  if(ValPreCVSDDE[2]<0) ValPreCVSDDE[2]=0;//-32768;
  ValPreCVSDDE[0]=ValPreCVSDDE[1];
  ValPreCVSDDE[1]=ValPreCVSDDE[2];
  m++;
  m%=3;
  
  //椭圆IIR滤波器
  OutData=(short)ValPreCVSDDE[2];
  Max=0;
  filterX[0]=OutData;
  for(j=0;j<ORD;j++)
  {
   Max=Max+CoefB[j]*filterX[j];
  }
  for(j=1;j<ORD;j++)
  {
   Max=Max-CoefA[j]*filterY[j];
  }
  DataDecode=(short)((((float)Max)/(48e24))*32767);
  for(j=ORD-1;j>0;j--)
  {
   filterX[j]=filterX[j-1];
  }
  for(j=ORD-1;j>0;j--)
  {
   filterY[j]=filterY[j-1];
  }
  filterY[0]=(short)Max;
  //return OutData;
  return DataDecode;
}