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Circular buffer problem in Dspic 30F4013

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malik_123

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I have written the following code to implement the circular buffer ,
code is working for the X-data space fine ,
but
for the Y-data space the same code does not work

Code:
#include <30F4013.h>
#FUSES NOWDT                    //No Watch Dog Timer
#FUSES HS                       //High speed Osc (> 4mhz for PCM/PCH) (>10mhz for PCD)
#FUSES NOCKSFSM                 //Clock Switching is disabled, fail Safe clock monitor is disabled
#FUSES WPSB16                   //Watch Dog Timer PreScalar B 1:16
#FUSES WPSA512                  //Watch Dog Timer PreScalar A 1:512
#FUSES PUT64                    //Power On Reset Timer value 64ms
#FUSES NOBROWNOUT               //No brownout reset
#FUSES BORRES                
#FUSES MCLR                     //Master Clear pin enabled
#FUSES NOPROTECT                //Code not protected from reading
#FUSES NOWRT                    //Program memory not write protected
#FUSES NODEBUG                  //No Debug mode for ICD
#FUSES ICSP                  
#use delay(clock=20000000)
#word CORCON  = getenv("SFR:CORCON")
#word MODCON  = getenv("SFR:MODCON")
#word XMODSRT = getenv("SFR:XMODSRT")
#word XMODEND = getenv("SFR:XMODEND")
#word YMODSRT = getenv("SFR:YMODSRT")
#word YMODEND = getenv("SFR:YMODEND")

signed int16 Circular_Buf[200];
#locate Circular_buf  = 0xC00  
signed int16 Cir[70];
#locate Cir  = 0x800


struct
{
   int XWM:4;
   int YWM:4;
   int BWM:4;
   int Reserved:2;
   int YMODEN:1;
   int XMODEN:1;
}MODCONbits;
#locate MODCONbits = getenv("SFR:MODCON")

void main(void)               
{

int i;
for (i=0;i<=40;i++)
{
   Circular_buf[i]=i;
   cir[i]=(i+23);
}


// setting for Y-data space , W1 is used as the pointer for circular buffer
   MODCONbits.XMODEN=0;  // X AGU modulus addressing enabled
   MODCONbits.YMODEN=1;  // Y AGU modulus addressing enabled
   MODCONbits.BWM=15; // Disable bit-reveresed addressing
   MODCONbits.XWM=15; // Use register W8  
   MODCONbits.YWM=1; //




// here I shall make a circular buffer in Y-data space , w1 will be a pointer 
// i shall move the ciruclar buffer value to W0 register and 
// shall view it on Mplab simulator , does not work 

#asm    
                                    
   MOV #0xC00,W0                              
   MOV W0,YMODSRT ;set modulo start address
   MOV #0xC24,W0
   MOV W0,YMODEND ;set modulo end address
   MOV #0xC00,W1 
   NOP
   DO #49,FILL ;fill the 50 buffer locations
   FILL:
   MOV [W1++],W0
   
  #endasm

// setting for X-data space , W2 is used as the pointer for circular buffer
   
MODCONbits.XMODEN=1;  // X AGU modulus addressing enabled
   MODCONbits.YMODEN=0;  // Y AGU modulus addressing enabled
   MODCONbits.BWM=15; // Disable bit-reveresed addressing
   MODCONbits.XWM=2; // Use register W8  
   MODCONbits.YWM=15; // Use register W9  

// here I shall make a circular buffer in X-data space , w2 will be a pointer 
// i shall move the ciruclar buffer value to W0 register and 
// shall view it on Mplab simulator , work properly 

#asm   
MOV #0x800,W0
MOV W0,XMODSRT ;set modulo start address
MOV #0x824,W0
MOV W0,XMODEND ;set modulo end address
MOV #0x0000,W0 ;W0 holds buffer fill value
MOV #0x800,W2 ;point W1 to buffer
DO #49,FIlLL ;fill the 50 buffer locations
FIlLL:
//MOV W0,[W1++] ;fill the next location
MOV [W2++], W0 ;fill the next location 
   
#endasm


}


i write the data in the two location
1) y-data space
2) x data space

when i implement the code for the x-data space the pointer automatically set to the initial value after the last value.

but in case of Y-data space it does not do so

I am checking the output on Mplab Simulator
 

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