📄 student.cpp
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//#ifdef __cplusplus
//extern "C" {
//#endif
/*==================================================================================================
Module Name: Student.cpp
General Description: Student write these functions
====================================================================================================
Semit
(c) Copyright SEMIT 2002, All Rights Reserved
Revision History:
Modification Tracking
------------------------- ------------ ---------- -------------------------------------------
Author Date Number Description of Changes
------------------------- ------------ ----------------------------------------
Semit 08/5/2002 Unknown A-Law PCM and CVSD encode and decode functions
====================================================================================================
INCLUDE FILES
==================================================================================================*/
#include <stdafx.h>
#include <math.h>
#include "Student.h"
/*==================================================================================================
LOCAL TYPEDEFS (STRUCTURES, UNIONS, ENUMS)
==================================================================================================*/
/*==================================================================================================
LOCAL VARIABLES
==================================================================================================*/
static STUDENT_CVSD Student_CVSD;
/*==================================================================================================
* GLOBAL FUNCTIONS
/*==================================================================================================
FUNCTION: PCM_StudentAlawEncode
DESCRIPTION:
This function is A-Law PCM encode function
ARGUMENTS PASSED:
InputValue: The inputed sample value , the range is -2047 ~ +2047
RETURN VALUE:
The 8-bits encoded value
PRE-CONDITIONS:
None
POST-CONDITIONS:
None
IMPORTANT NOTES:
==================================================================================================*/
extern unsigned char PCM_StudentAlawEncode(int InputValue)
{
unsigned char OutputValue = 0x0;
int temp=InputValue,i=0;
int a[2]={0},k,j;
if(temp>32&&temp<=64) //用13折线法将采样值编码
{
temp=32+(temp-32)/2;
}
if(temp>64&&temp<=128)
{
temp=48+(temp-64)/4;
}
if(temp>128&&temp<=256)
{
temp=64+(temp-128)/8;
}
if(temp>256&&temp<=512)
{
temp=80+(temp-256)/16;
}
if(temp>512&&temp<=1024)
{
temp=96+(temp-512)/32;
}
if(temp>1024&&temp<2048)
{
temp=112+(temp-1024)/64;
}
while(temp>=16) //将编码后的值转换成16进制
{ //存储在数组a[]中
a[i]=temp%16;
temp=temp/16;
i++;
}
a[i]=temp;
for(j=0;j<2;j++) //将16进制数用相应字母表示
{
if(a[j]==10)
{
a[j]=0xa;
continue;
}
if(a[j]==11)
{
a[j]=0xb;
continue;
}
if(a[j]==12)
{
a[j]=0xc;
continue;
}
if(a[j]==13)
{
a[j]=0xd;
continue;
}
if(a[j]==14)
{
a[j]=0xe;
continue;
}
if(a[j]==15)
{
a[j]=0xf;
continue;
}
}
k=a[1]*0x10+a[0]+0x80; //整合16进制数的个位和十位，将值赋给k
OutputValue = k;
/*Add your code here*/
return OutputValue; //将16进制数以2进制的形式返回
}
/*==================================================================================================
FUNCTION: PCM_StudentAlawDecode
DESCRIPTION:
This function is A-Law PCM dencode function
ARGUMENTS PASSED:
CodeValue: The 8-bits encoded value
RETURN VALUE:
The decoded sample value
PRE-CONDITIONS:
None
POST-CONDITIONS:
None
IMPORTANT NOTES:
==================================================================================================*/
extern int PCM_StudentAlawDecode(unsigned char CodeValue)
{
int DecodeValue = 0;
int kt=CodeValue-0x80;
if(kt>=112) //用反变换的方式将编码值还原
{
kt=1024+(kt-112)*64;
}
if(kt>=96&&kt<112)
{
kt=512+(kt-96)*32;
}
if(kt>=80&&kt<96)
{
kt=256+(kt-80)*16;
}
if(kt>=64&&kt<80)
{
kt=128+(kt-64)*8;
}
if(kt>=48&&kt<64)
{
kt=64+(kt-48)*4;
}
if(kt>=32&&kt<48)
{
kt=32+(kt-32)*2;
}
DecodeValue=kt;
/*Add your code here*/
return DecodeValue; //返回解码后的值，即源码
}
/*==================================================================================================
FUNCTION: CVSD_StudentEncode
DESCRIPTION:
This function is CVSD encode function
ARGUMENTS PASSED:
Amplitude: The sin wave amplitude , the range is 0 - 32767
Frequency: The sin wave frequency , the range is 4*1024 - 16* 1024
SampleTimes: The times of sample , the range is 10 - 30
The sample value is computed as follows:
Sample[i] = Amplitude * sin(2 * PI * Frequency * (double)i /(double)(64*1024));
RETURN VALUE:
The pointer to struct Student_CVSD, the member 'Encode' of the struct is the cvsd code.
PRE-CONDITIONS:
None
POST-CONDITIONS:
None
IMPORTANT NOTES:
==================================================================================================*/
extern STUDENT_CVSD* CVSD_StudentEncode(int Amplitude, int SampleTimes, int Frequency)
{
int i;
double Sample[31];
for(i = 0; i <= SampleTimes; i ++){ /*64khz is the sample frequency*/
Sample[i] = Amplitude * sin(2 * PI * Frequency * (double)i /(double)(64*1024));
}
double h=0.96875,bt=0.9990234375;
int dmin=10,dmax=1280,b[30]={0};
double* x;
double xe[30]={0},yReal=0,y[30]={0},d[30]={0};
long double ymin=-1,ymax=1;
for(i=0;i<15;i++) //求y的上限和下限
{
ymin=ymin*2;
ymax=ymax*2;
}
ymin=ymin+1;
ymax=ymax-1;
x=Sample; //将正弦波采样值赋给
for(i=0;i<SampleTimes;i++)
{
b[i]=(x[i]-xe[i])>=0 ? 1:0; //编码值b[i]
if(i>2&&b[i]==b[i-1]&&b[i]==b[i-2]&&b[i]==b[i-3]) //确定量阶d[i]
{
d[i]=min(d[i-1]+dmin,dmax);
}
else
{
d[i]=max(bt*d[i-1],dmin);
}
if(b[i]) //确定累加器参数的估计值y[i]
{
y[i]=xe[i]+d[i];
}
else
{
y[i]=xe[i]-d[i];
}
if(y[i]>=0) //确定累加器的值yReal
{
yReal=min(y[i],ymax);
}
else
{
yReal=max(y[i],ymin);
}
if(i>0)
{
xe[i+1]=h*yReal; //确定当前估计值xe[i]
}
Student_CVSD.Encode[i]=b[i];
}
/*Add your code here*/
return &Student_CVSD;
}
/*==================================================================================================
FUNCTION: CVSD_StudentDecode
DESCRIPTION:
This function is CVSD decode function
ARGUMENTS PASSED:
SampleTimes: The times of sample
Use the member 'Encode'of struct Student_CVSD
RETURN VALUE:
The pointer to struct Student_CVSD, the member 'Decode' of the struct is the decoded value.
PRE-CONDITIONS:
None
POST-CONDITIONS:
None
IMPORTANT NOTES:
==================================================================================================*/
extern STUDENT_CVSD* CVSD_StudentDecode(int SampleTimes)
{
int i;
int* b;
double h=0.96875,bt=0.9990234375;
int dmin=10,dmax=1280;
double xe[32]={0},yReal=0,y[30]={0},d[30]={0};
long double ymin=-1,ymax=1;
for(i=0;i<15;i++) //过程与编码过程大致相同
{ //除编码值b[]为已知
ymin=ymin*2;
ymax=ymax*2;
}
ymin=ymin+1;
ymax=ymax-1;
b=Student_CVSD.Encode;
for(i=0;i<SampleTimes;i++)
{
if(i>3&&b[i]==b[i-1]&&b[i]==b[i-2]&&b[i]==b[i-3]) //确定量阶d[i]
{
d[i]=min(d[i-1]+dmin,dmax);
}
else
{
d[i]=max(bt*d[i-1],dmin);
}
if(b[i]) //确定累加器参数的估计值y[i]
{
y[i]=xe[i]+d[i];
}
else
{
y[i]=xe[i]-d[i];
}
if(y[i]>=0) //确定累加器的值yReal
{
yReal=min(y[i],ymax);
}
else
{
yReal=max(y[i],ymin);
}
if(i>0)
{
xe[i+1]=h*yReal; //确定当前估计值xe[i]
}
Student_CVSD.Decode[i]=xe[i];
}
/*Add your code here*/
return &Student_CVSD;
}
/*===========================================================================================*/
//#ifdef __cplusplus
//}
//#endif⌨️ 快捷键说明
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