HELP PLEASE

I don't know anything about you HW but I can comment on the code. Your code is just missing a few shifts. Assuming your samples are truly 16 bit unsigned values:

Uint16 increase_by(Uint16 x, Uint16 n)
{
  Uint32 y = x;              // Transfer to 32 bit register
  y *= n;                    // Multiply by n
  if(y > 0xFFFF) y = 0xFFFF; // Clip if larger than 16 bits.
  return((Uint16)y);         // Return 16 bits.
}

Uint16 decrease_by(Uint16 x, Uint16 n)
{
  x /= n;     // Divide.
  return(x);  // Return 16 bits.
}

Uint32 sample_mul(Uint32 sample, Uint16 n)
{
    Uint16 rhchannel;
    Uint16 lfchannel;

    rhchannel  = (Uint16)sample; // Extract right
    sample   >>= 16;             // Shift down the next value
    lfchannel  = (Uint16)sample; // Extract left

    rhchannel = increase_by(rhchannel, n);
    lfchannel = increase_by(lfchannel, n);

    sample   = lfchannel; // Left in bottom
    sample <<= 16;        // Shift up to upper
    sample  |= rhchannel; // Right in bottom.

    return(sample);
}

Uint32 sample_div(Uint32 sample, Uint16 n)
{
    Uint16 rhchannel;
    Uint16 lfchannel;

    rhchannel  = (Uint16)sample; // Extract right
    sample   >>= 16;             // Shift down the next value
    lfchannel  = (Uint16)sample; // Extract left

    rhchannel = decrease_by(rhchannel, n);
    lfchannel = decrease_by(lfchannel, n);

    sample   = lfchannel; // Left in bottom
    sample <<= 16;        // Shift up to upper
    sample  |= rhchannel; // Right in bottom.

    return(sample);
}
...
    while(1){
      
        while(!MCBSP_rrdy(_MCBSP_hDev1)){
    }
    sample=MCBSP_read(_MCBSP_hDev1);
#if 1
    sample=sample_mul(sample,n);
#else
    sample=sample_div(sample,n);
#endif
    while(!MCBSP_xrdy(_MCBSP_hDev1)){
    }
    MCBSP_write(_MCBSP_hDev1,sample);
    }
...

Slightly different if they are signed values. Not guarantees about the real time performance of multplys and divides.

Hello, its me again,
unfortunately my problem remains.
I've tried to use your functions but if i try to divide or multiply a channel by a non-integer number,
even if i used "printf" to ensure that the modified channel was again an integer number, and it was,
the output was distorted.
Another problem is that, with your functions, if i use "sample_mul" to multiply rhchannel by 2 (integer)
the distorsion remains.
This doesn't happen if simply i multiply rhchannel in this way.....rhchannel*=2;

Let me show you some examples ( rhchannel...lfchannel...is the same thing ):

...
rhchannel*=2;  this works and the "right headphone" volume increase by 2
lfchannel*=2;
...

...
sample_mul(sample,2);   this make distortion on output and doesn't increase the volume
...

...
rhchannel*=2.1;     this doesn't increase the "right headphone" volume, instead it make distortion on output
...

...
rhchannel>>=1;      this doesn't divide by 2 the volume, instead it make distortion on output
...

...
heyhomie=rhchannel;     the volume is increased
heyhomie*=2;
rhchannel=heyhomie;
...

heyhomie=rhchannel;     this make distortion without decrease the "right headphone" volume
heyhomie>>=1;
rhchannel=heyhomie;
...

Anyway, my sampling rate is 41 KHz, but i will need to 80 KHz, more or less.

I don't know nothing about DSPs (i'm programming this DSK for a school project)
but this problem is inexplicable, cos sometimes the program works good but sometimes not. Incredible!

In fact, your code is right, and mine too.

(maybe there's a problem in my DSP/BIOS config file, i didn't modify it, but it's strange that
 with integer numbers the program works,and with casting or simply shifting to the right there's
 a distortion on output)

The things i said in the last post are still valid.

Maybe, if you want, i can send you my folder where there's my project, but in this case i need an e-mail
address where i'll be able to send the files.

Please, take a look on this modified code, i used first your functions, then i tried an alternative method
to make the division by two using only right shifts   ( <<= )..... incredibly the distortion persist....

Thank you for your attention.
 


#include "dsk6713.h"
#include <csl.h>
#include "dsk6713_aic23.h"
#include <stdio.h>

#include "MyConfigDSPbioscfg.h"

Uint16 increase_by(Uint16 x, Uint16 n);
Uint16 decrease_by(Uint16 x, Uint16 n);
Uint32 sample_mul(Uint32 sample, Uint16 n);
Uint32 sample_div(Uint32 sample, Uint16 n);



void main()
{

    Uint32 sample, rhchannel, lfchannel, heyhomie=0, findmask=1, i=15;
    MCBSP_Config myMCBSPconf;

    DSK6713_AIC23_CodecHandle hCodec;

    DSK6713_AIC23_Config myConfAic={
        0x0117,  //adjust the left LINEinput volume.
        0x0117,  //adjust the right LINEinput volume.
        0x00FF,  //adjust the left Headphone volume.
        0x00FF,  //adjust the right Headphone volume.
        0x0012,  //AnalogAudioPathControl...enable the DAC, disable the Bypass, set the LINEinput as mine input instead of the microphone.
        0x0000,  //DigitalAudioPathControl...I don't know...
        0x0002,  //PowerDownControl...turn on the various things that i need, like DAC, ADC, etc..
        0x0043,  //DigitalAudioInterface...AIC = master mode, data format = DSP mode, lenght of a word = 16 bit, etc..
        0x0023,  //SamplingRateControl...i use USB mode so master clock is 12MHz, remaining bits are used to set the sample rate.
        0x0001   //DigitalInterfaceActivation...enable the interface.
    };

    DSK6713_init();
    CSL_init();
   
    hCodec=DSK6713_AIC23_openCodec(0,&myConfAic);

    MCBSP_getConfig(_MCBSP_hDev1,&myMCBSPconf);
    myMCBSPconf.rcr=0x1A0;  //McBSP works with one phase and one word (32 bits), in this way i can easily recognize left channel and right channel.(respectively first 16 bit and last 16 bits)
    myMCBSPconf.xcr=0x1A0;

    MCBSP_config(_MCBSP_hDev1,&myMCBSPconf);

    findmask<<=31;     //use this for LOOP1

    //findmask<<=15;   //use this for LOOP2   

    while(1){
       
        while(!MCBSP_rrdy(_MCBSP_hDev1)){
    }
    sample=MCBSP_read(_MCBSP_hDev1);

    rhchannel=sample&(0x0000FFFF);
    lfchannel=sample&(0xFFFF0000);

    //heyhomie>>=1;                     doesn't work
    //heyhomie=(float)(heyhomie*0.5);   doesn't work
    //rhchannel/=2;                     doesn't work

//LOOP1---------------------------------------------------------------------
//       this loop1 divide by two rhchannel putting the result in heyhomie
//       WITHOUT shift to the right any variable
       
    heyhomie=0;
    rhchannel<<=16;
    while(i>0){       // i starts from 15
        i--;
        heyhomie<<=1;
        if(rhchannel&findmask)
            heyhomie+=1;
        rhchannel<<=1;
    }
    i=15;

//LOOP2---------------------------------------------------------------------
//       this loop2 does the same thing that does loop1, without shift rxchannel
//       but shifting to the right findmask
       
       
    //while(i>0){     // i starts from 15
    //    i--;
    //    heyhomie<<=1;
    //    if(rhchannel&findmask)
    //        heyhomie+=1;
    //    findmask>>=1;
    //}
    //i=15;
    //findmask<<=15;  

//--------------------------------------------------------------------------        

    rhchannel=heyhomie;
   
    sample=rhchannel|lfchannel;


        //sample=sample_mul(sample,2);   Doesn't work.
   

    while(!MCBSP_xrdy(_MCBSP_hDev1)){
    }
    MCBSP_write(_MCBSP_hDev1,sample);
    }
}

Uint16 increase_by(Uint16 x, Uint16 n)
{
  Uint32 y = x;              // Transfer to 32 bit register
  y *= n;                    // Multiply by n
  if(y > 0xFFFF) y = 0xFFFF; // Clip if larger than 16 bits.
  return((Uint16)y);         // Return 16 bits.
}

Uint16 decrease_by(Uint16 x, Uint16 n)
{
  x /= n;     // Divide.
  return(x);  // Return 16 bits.
}

Uint32 sample_mul(Uint32 sample, Uint16 n)
{
    Uint16 rhchannel;
    Uint16 lfchannel;

    rhchannel  = (Uint16)sample; // Extract right
    sample   >>= 16;             // Shift down the next value
    lfchannel  = (Uint16)sample; // Extract left

    rhchannel = increase_by(rhchannel, n);
    lfchannel = increase_by(lfchannel, n);

    sample   = lfchannel; // Left in bottom
    sample <<= 16;        // Shift up to upper
    sample  |= rhchannel; // Right in bottom.

    return(sample);
}

Uint32 sample_div(Uint32 sample, Uint16 n)
{
    Uint16 rhchannel;
    Uint16 lfchannel;

    rhchannel  = (Uint16)sample; // Extract right
    sample   >>= 16;             // Shift down the next value
    lfchannel  = (Uint16)sample; // Extract left

    rhchannel = decrease_by(rhchannel, n);
    lfchannel = decrease_by(lfchannel, n);

    sample   = lfchannel; // Left in bottom
    sample <<= 16;        // Shift up to upper
    sample  |= rhchannel; // Right in bottom.

    return(sample);
}

Are you sure the samples are unsigned?

Ok,

now that you've said that     im not quite sure.

I'm not alone in this project so i am going to ask my partner tomorrow.

Tomorrow we'll try to consider those samples like signed values, and then

i'll answer you.

Hello, Mr. Wong
i need to say "THANK YOU VERY MUCH".
You were right, that samples are signed values, and your functions work good.
My partner has said you are a big BOSS. I agree.

(maybe i'll need help again in future, i'll post here if there's no problems)

(rereading my posts i've realized i've written "right shift" instead of "left sh." and viceversa.
 I apologize if this has created confusion hehe :)   )

Thanks again for your quick replies,

goodbye,

Olsen.