Variance Calculation Using Blackfin

Hi
I am determining the Variance in Blackfin DSP using assembly language.
I compared with the c code under following cases

1. 8 samples
2. 16 samples
3. 32 samples
4. 1024 samples.

I got correct result under case 1 and case 2. But i am not getting correct result under case 3 and 4. C and Assembly codes are below. Also shared at
http://www.4shared.com/file/210861924/d79c05b4/VarianceCalc.html
Can somebody tell me where is the wrong.

#include
#include
#include

#define MAX_SIZE 32//1024

float InputData[MAX_SIZE] ={
0.25005,0.59361,0.16858,0.66254,
0.73142,0.14195,-0.42078,-0.21316,
-0.28167,0.68526,0.76273,0.35498,
0.5977,0.17204,0.24829,0.052611
-0.1665,-0.79421,0.062438,0.094364,
0.43401,-0.011778,0.17192,0.98137,
0.54351,0.91544,-0.97341,0.12246,
0.0055164,-0.014214,0.97314,0.36023
/* 0.44436,-0.43146,0.20522,0.47057,
0.6912,0.44631,0.41747,0.23028,
-0.86039,0.94002,-0.31636,0.97059,
-0.88821,0.82206,0.64462,0.835,
0.047385,0.59136,0.99241,0.25644,
0.10618,0.24282,0.32284,0.55811,
-0.29633,0.70868,-0.43582,-0.84618,
0.24908,-0.82105,-0.82567,0.25509,
0.73364,0.66384,0.78594,0.7538,
0.99733,0.7704,0.88123,-0.35055,
0.80984,-0.97032,0.23707,

*/
// #include "RandomSig.dat"
};

short InputDataFr16[MAX_SIZE];
short VarianceVal;

void main(){
short i;
float Sum=0.0;
float MeanValue;
float SquareDiff;
float M;
float VarianceFloat,VarianceSum=0.0;
for (i=0;i InputDataFr16[i] = float_to_fr16(InputData[i]);
}

for(i=0;i Sum += InputData[i];
}

M = (float)MAX_SIZE;
MeanValue = Sum/M;
printf( " Average Using C is %f\n",MeanValue);

for(i=0;i SquareDiff = pow((InputData[i]-MeanValue),2.0);
// printf("%f\n",SquareDiff);
VarianceSum += SquareDiff;
}
VarianceSum = VarianceSum/M;
printf("Variance is %f\n", VarianceSum);


_VarianceCalculate(&InputDataFr16[0],&VarianceVal,MAX_SIZE);
VarianceFloat = fr16_to_float(VarianceVal);
printf("Variance Value Using Assembly = %f\n", VarianceFloat);

}

.section/code program;
.global __VarianceCalculate;

__VarianceCalculate:
I0 = R0; // Signal
I1 = R1; // Variance Address
LC0 = R2; // Buffer Length
LC1 = R2;
R3 = 0;
R4 = 0;
LSETUP(_AverageStart,_AverageEnd) LC0;
_AverageStart:
R3.H = W[ I0 ++ ];
R3 = R3>>>5;
_AverageEnd:
R4 = R4 + R3; // Mean Value at R4 register
I0 = R0;
R3 = 0;
A0 = 0;

LSETUP(_VarianceStart,_VarianceEnd) LC1;
_VarianceStart:
R3.H = W[ I0 ++ ];
R2 = R3 - R4;
_VarianceEnd:
A0 +=R2.H*R2.H;
A0 = A0>>>5;
R0 = A0;
W[ I1 ] = R0.H;
RTS;
NOP;
__VarianceCalculate.end:

Regards
Gnanavel

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Dear Velu san,
Blackfin for simple people and simple applications ( !!!!! dont take it as it is... but hint is the following).

Blackfin will be using ACC to store sum value that comes out of each iteration of for loop. I think ACC itself getting overflow mode when you go for 32 or 1024 samples based for loop. If we assume this is true then we can find N number of solutions for the same.

most primitive....
just make many ( needful number) 16 samples loop to solve 32 or 1024. In this, mem will be used as a ACC at the end for loop ( 16 times) and add them or divide them and add them. I mean you can divide each loop by 16 to get value and add result... this will help. If you want c code i can write but i want you to write and enjoy the joy working with primitive computing machines.
Advanced hint.
Select fractional format such that ACC does not overflow ( this will be data dependent and you need to know more details about your data array). Without details about data array it is not east to decide format.

Have a nice week end.

Kind Regards
jk

----- Original Message -----
From: Gnanavelu
To: a...
Sent: Saturday, January 30, 2010 9:18 AM
Subject: [adsp] Variance Calculation Using Blackfin

Hi
I am determining the Variance in Blackfin DSP using assembly language.
I compared with the c code under following cases

1. 8 samples
2. 16 samples
3. 32 samples
4. 1024 samples.

I got correct result under case 1 and case 2. But i am not getting correct result under case 3 and 4. C and Assembly codes are below. Also shared at
http://www.4shared.com/file/210861924/d79c05b4/VarianceCalc.html
Can somebody tell me where is the wrong.

#include
#include
#include

#define MAX_SIZE 32//1024

float InputData[MAX_SIZE] ={
0.25005,0.59361,0.16858,0.66254,
0.73142,0.14195,-0.42078,-0.21316,
-0.28167,0.68526,0.76273,0.35498,
0.5977,0.17204,0.24829,0.052611
-0.1665,-0.79421,0.062438,0.094364,
0.43401,-0.011778,0.17192,0.98137,
0.54351,0.91544,-0.97341,0.12246,
0.0055164,-0.014214,0.97314,0.36023
/* 0.44436,-0.43146,0.20522,0.47057,
0.6912,0.44631,0.41747,0.23028,
-0.86039,0.94002,-0.31636,0.97059,
-0.88821,0.82206,0.64462,0.835,
0.047385,0.59136,0.99241,0.25644,
0.10618,0.24282,0.32284,0.55811,
-0.29633,0.70868,-0.43582,-0.84618,
0.24908,-0.82105,-0.82567,0.25509,
0.73364,0.66384,0.78594,0.7538,
0.99733,0.7704,0.88123,-0.35055,
0.80984,-0.97032,0.23707,

*/
// #include "RandomSig.dat"
};

short InputDataFr16[MAX_SIZE];
short VarianceVal;

void main(){
short i;
float Sum=0.0;
float MeanValue;
float SquareDiff;
float M;
float VarianceFloat,VarianceSum=0.0;
for (i=0;i InputDataFr16[i] = float_to_fr16(InputData[i]);
}

for(i=0;i Sum += InputData[i];
}

M = (float)MAX_SIZE;
MeanValue = Sum/M;
printf( " Average Using C is %f\n",MeanValue);

for(i=0;i SquareDiff = pow((InputData[i]-MeanValue),2.0);
// printf("%f\n",SquareDiff);
VarianceSum += SquareDiff;
}
VarianceSum = VarianceSum/M;
printf("Variance is %f\n", VarianceSum);

_VarianceCalculate(&InputDataFr16[0],&VarianceVal,MAX_SIZE);
VarianceFloat = fr16_to_float(VarianceVal);
printf("Variance Value Using Assembly = %f\n", VarianceFloat);

}

.section/code program;
.global __VarianceCalculate;

__VarianceCalculate:
I0 = R0; // Signal
I1 = R1; // Variance Address
LC0 = R2; // Buffer Length
LC1 = R2;
R3 = 0;
R4 = 0;
LSETUP(_AverageStart,_AverageEnd) LC0;
_AverageStart:
R3.H = W[ I0 ++ ];
R3 = R3>>>5;
_AverageEnd:
R4 = R4 + R3; // Mean Value at R4 register
I0 = R0;
R3 = 0;
A0 = 0;

LSETUP(_VarianceStart,_VarianceEnd) LC1;
_VarianceStart:
R3.H = W[ I0 ++ ];
R2 = R3 - R4;
_VarianceEnd:
A0 +=R2.H*R2.H;
A0 = A0>>>5;
R0 = A0;
W[ I1 ] = R0.H;
RTS;
NOP;
__VarianceCalculate.end:

Regards
Gnanavel

------
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What jk said is correct - in your C you have defined things as "float",
but in assembler you are using ints. Look at the assembly from the
C compiler (-S switch or click on something that will generate it).

To get different results for both C and assembler, look into setting up
the "saturation mode". And for both integer and fractional modes.
You will get a lot of different answers - all of them correct :-)

Patience, persistence, truth,
Dr. mike

On Sat, 30 Jan 2010, Dr Jayakumar Singaram wrote:

> Dear Velu san,
> Blackfin for simple people and simple applications ( !!!!! dont take it as it is... but hint is the following).
>
> Blackfin will be using ACC to store sum value that comes out of each iteration of for loop. I think ACC itself getting overflow mode when you go for 32 or 1024 samples based for loop. If we assume this is true then we can find N number of solutions for the same.
>
> most primitive....
> just make many ( needful number) 16 samples loop to solve 32 or 1024. In this, mem will be used as a ACC at the end for loop ( 16 times) and add them or divide them and add them. I mean you can divide each loop by 16 to get value and add result... this will help. If you want c code i can write but i want you to write and enjoy the joy working with primitive computing machines.
> Advanced hint.
> Select fractional format such that ACC does not overflow ( this will be data dependent and you need to know more details about your data array). Without details about data array it is not east to decide format.
>
> Have a nice week end.
>
> Kind Regards
> jk
>
> ----- Original Message -----
> From: Gnanavelu
> To: a...
> Sent: Saturday, January 30, 2010 9:18 AM
> Subject: [adsp] Variance Calculation Using Blackfin
>
> Hi
> I am determining the Variance in Blackfin DSP using assembly language.
> I compared with the c code under following cases
>
> 1. 8 samples
> 2. 16 samples
> 3. 32 samples
> 4. 1024 samples.
>
> I got correct result under case 1 and case 2. But i am not getting correct result under case 3 and 4. C and Assembly codes are below. Also shared at
> http://www.4shared.com/file/210861924/d79c05b4/VarianceCalc.html
> Can somebody tell me where is the wrong.
>
> #include
> #include
> #include #define MAX_SIZE 32//1024
>
> float InputData[MAX_SIZE] ={
> 0.25005,0.59361,0.16858,0.66254,
> 0.73142,0.14195,-0.42078,-0.21316,
> -0.28167,0.68526,0.76273,0.35498,
> 0.5977,0.17204,0.24829,0.052611
> -0.1665,-0.79421,0.062438,0.094364,
> 0.43401,-0.011778,0.17192,0.98137,
> 0.54351,0.91544,-0.97341,0.12246,
> 0.0055164,-0.014214,0.97314,0.36023
> /* 0.44436,-0.43146,0.20522,0.47057,
> 0.6912,0.44631,0.41747,0.23028,
> -0.86039,0.94002,-0.31636,0.97059,
> -0.88821,0.82206,0.64462,0.835,
> 0.047385,0.59136,0.99241,0.25644,
> 0.10618,0.24282,0.32284,0.55811,
> -0.29633,0.70868,-0.43582,-0.84618,
> 0.24908,-0.82105,-0.82567,0.25509,
> 0.73364,0.66384,0.78594,0.7538,
> 0.99733,0.7704,0.88123,-0.35055,
> 0.80984,-0.97032,0.23707,
>
> */
> // #include "RandomSig.dat"
> };
>
> short InputDataFr16[MAX_SIZE];
> short VarianceVal;
>
> void main(){
> short i;
> float Sum=0.0;
> float MeanValue;
> float SquareDiff;
> float M;
> float VarianceFloat,VarianceSum=0.0;
> for (i=0;i > InputDataFr16[i] = float_to_fr16(InputData[i]);
> }
>
> for(i=0;i > Sum += InputData[i];
> }
>
> M = (float)MAX_SIZE;
> MeanValue = Sum/M;
> printf( " Average Using C is %f\n",MeanValue);
>
> for(i=0;i > SquareDiff = pow((InputData[i]-MeanValue),2.0);
> // printf("%f\n",SquareDiff);
> VarianceSum += SquareDiff;
> }
> VarianceSum = VarianceSum/M;
> printf("Variance is %f\n", VarianceSum);
> _VarianceCalculate(&InputDataFr16[0],&VarianceVal,MAX_SIZE);
> VarianceFloat = fr16_to_float(VarianceVal);
> printf("Variance Value Using Assembly = %f\n", VarianceFloat);
>
> }
>
> .section/code program;
> .global __VarianceCalculate;
>
> __VarianceCalculate:
> I0 = R0; // Signal
> I1 = R1; // Variance Address
> LC0 = R2; // Buffer Length
> LC1 = R2;
> R3 = 0;
> R4 = 0;
> LSETUP(_AverageStart,_AverageEnd) LC0;
> _AverageStart:
> R3.H = W[ I0 ++ ];
> R3 = R3>>>5;
> _AverageEnd:
> R4 = R4 + R3; // Mean Value at R4 register
> I0 = R0;
> R3 = 0;
> A0 = 0;
>
> LSETUP(_VarianceStart,_VarianceEnd) LC1;
> _VarianceStart:
> R3.H = W[ I0 ++ ];
> R2 = R3 - R4;
> _VarianceEnd:
> A0 +=R2.H*R2.H;
> A0 = A0>>>5;
> R0 = A0;
> W[ I1 ] = R0.H;
> RTS;
> NOP;
> __VarianceCalculate.end:
> Regards
> Gnanavel
>
> ------
> Your Mail works best with the New Yahoo Optimized IE8. Get it NOW!. Start a New Thread

Dear Mike and JK,

Thanks for your suggestion. but your suggestions are wrong. The actual problem is number format. In my assembly code  i used Q15 format.The Average value is 0.225326. When you find the difference from the mean. For an example , the sample value (-0.79421-0.225326) you will get -1.01951. Actually Q15 format range is from -0.9 to 0.9. So to avoid this i convert Q15 to Q14 format then solved the issue.

Regards
GJ
--- On Sun, 31/1/10, Mike Rosing wrote:

From: Mike Rosing
Subject: Re: [adsp] Variance Calculation Using Blackfin
To: "Dr Jayakumar Singaram"
Cc: a..., "Gnanavelu"
Date: Sunday, 31 January, 2010, 7:37 AM



What jk said is correct - in your C you have defined things as "float",

but in assembler you are using ints. Look at the assembly from the

C compiler (-S switch or click on something that will generate it).

To get different results for both C and assembler, look into setting up

the "saturation mode". And for both integer and fractional modes.

You will get a lot of different answers - all of them correct :-)

Patience, persistence, truth,

Dr. mike

On Sat, 30 Jan 2010, Dr Jayakumar Singaram wrote:

> Dear Velu san,

> Blackfin for simple people and simple applications ( !!!!! dont take it as it is... but hint is the following).

>

> Blackfin will be using ACC to store sum value that comes out of each iteration of for loop. I think ACC itself getting overflow mode when you go for 32 or 1024 samples based for loop. If we assume this is true then we can find N number of solutions for the same.

>

> most primitive... .

> just make many ( needful number) 16 samples loop to solve 32 or 1024. In this, mem will be used as a ACC at the end for loop ( 16 times) and add them or divide them and add them. I mean you can divide each loop by 16 to get value and add result... this will help. If you want c code i can write but i want you to write and enjoy the joy working with primitive computing machines.

>

>

> Advanced hint.

> Select fractional format such that ACC does not overflow ( this will be data dependent and you need to know more details about your data array). Without details about data array it is not east to decide format.

>

> Have a nice week end.

>

> Kind Regards

> jk

>

> ----- Original Message -----

> From: Gnanavelu

> To: adsp@yahoogroups. com

> Sent: Saturday, January 30, 2010 9:18 AM

> Subject: [adsp] Variance Calculation Using Blackfin

>

>

>

> Hi

> I am determining the Variance in Blackfin DSP using assembly language.

> I compared with the c code under following cases

>

> 1. 8 samples

> 2. 16 samples

> 3. 32 samples

> 4. 1024 samples.

>

> I got correct result under case 1 and case 2. But i am not getting correct result under case 3 and 4. C and Assembly codes are below. Also shared at

> http://www.4shared. com/file/ 210861924/ d79c05b4/ VarianceCalc. html

>

>

> Can somebody tell me where is the wrong.

>

> #include

> #include

> #include

>

> #define MAX_SIZE 32//1024

>

> float InputData[MAX_ SIZE] ={

> 0.25005,0.59361, 0.16858,0. 66254,

> 0.73142,0.14195, -0.42078, -0.21316,

> -0.28167,0.68526, 0.76273,0. 35498,

> 0.5977,0.17204, 0.24829,0. 052611

> -0.1665,-0.79421, 0.062438, 0.094364,

> 0.43401,-0.011778, 0.17192,0. 98137,

> 0.54351,0.91544, -0.97341, 0.12246,

> 0.0055164,-0. 014214,0. 97314,0.36023

> /* 0.44436,-0.43146, 0.20522,0. 47057,

> 0.6912,0.44631, 0.41747,0. 23028,

> -0.86039,0.94002, -0.31636, 0.97059,

> -0.88821,0.82206, 0.64462,0. 835,

> 0.047385,0.59136, 0.99241,0. 25644,

> 0.10618,0.24282, 0.32284,0. 55811,

> -0.29633,0.70868, -0.43582, -0.84618,

> 0.24908,-0.82105, -0.82567, 0.25509,

> 0.73364,0.66384, 0.78594,0. 7538,

> 0.99733,0.7704, 0.88123,- 0.35055,

> 0.80984,-0.97032, 0.23707,

>

> */

> // #include "RandomSig.dat"

> };

>

> short InputDataFr16[ MAX_SIZE] ;

> short VarianceVal;

>

> void main(){

> short i;

> float Sum=0.0;

> float MeanValue;

> float SquareDiff;

> float M;

> float VarianceFloat, VarianceSum= 0.0;

> for (i=0;i
> InputDataFr16[ i] = float_to_fr16( InputData[ i]);

> }

>

> for(i=0;i
> Sum += InputData[i] ;

> }

>

> M = (float)MAX_SIZE;

> MeanValue = Sum/M;

> printf( " Average Using C is %f\n",MeanValue) ;

>

> for(i=0;i
> SquareDiff = pow((InputData[ i]-MeanValue) ,2.0);

> // printf("%f\n" ,SquareDiff) ;

> VarianceSum += SquareDiff;

> }

> VarianceSum = VarianceSum/ M;

> printf("Variance is %f\n", VarianceSum) ;

>

>

> _VarianceCalculate( &InputDataFr16[ 0],&VarianceVal, MAX_SIZE) ;

> VarianceFloat = fr16_to_float( VarianceVal) ;

> printf("Variance Value Using Assembly = %f\n", VarianceFloat) ;

>

> }

>

>

>

>

>

> .section/code program;

> .global __VarianceCalculate ;

>

> __VarianceCalculate :

> I0 = R0; // Signal

> I1 = R1; // Variance Address

> LC0 = R2; // Buffer Length

> LC1 = R2;

> R3 = 0;

> R4 = 0;

> LSETUP(_AverageStar t,_AverageEnd) LC0;

> _AverageStart:

> R3.H = W[ I0 ++ ];

> R3 = R3>>>5;

> _AverageEnd:

> R4 = R4 + R3; // Mean Value at R4 register

> I0 = R0;

> R3 = 0;

> A0 = 0;

>

> LSETUP(_VarianceSta rt,_VarianceEnd) LC1;

> _VarianceStart:

> R3.H = W[ I0 ++ ];

> R2 = R3 - R4;

> _VarianceEnd:

> A0 +=R2.H*R2.H;

> A0 = A0>>>5;

> R0 = A0;

> W[ I1 ] = R0.H;

> RTS;

> NOP;

> __VarianceCalculate .end:

>

>

>

>

> Regards

> Gnanavel

> Start a New Thread