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changing buffer from data to xdata

The following code fragment has been running for three years on an Atmel 89c55 with no problems. Now that I have started a project using the Cypress EZ-USB FX chip I would like to move the fifo buffer from the default generic pointer in data space.

#define FIFO0SIZE 10
BYTE *fifo0[FIFO0SIZE];

to xdata and increase the size using

#define FIFO0SIZE 100
xdata BYTE *fifo0[FIFO0SIZE];

It compiles but continualy sends garbage out the serial port.
I have tried pointer casting and changing to the large memory modle and a few other things, all with negative results.

Can anyone shed some light on this problem.

#define FIFO0FULL FIFO0SIZE-2
BYTE Que(new_ptr)
BYTE *new_ptr;
{
BYTE idata Pass,i;
Pass=0xff;
for(i=0;i<FIFO0SIZE-1;i++){
// add new message to end of buffer
if(!fifo0[i]){
// current position is empty go ahead and use it
if(i>FIFO0FULL) SBuff0_Full=1;
Pass=0;
fifo0[i]=(BYTE xdata *) new_ptr;
fifo0[i+1]=0;
if(!out0_busy) TI=1; // kick start the uart
break;
}
}
return Pass;
}

void Serial_Port0(void) interrupt COM0_VECT
{
BYTE idata i;
static BYTE data x=0;

if(RI) {
RI=0; // extract recieved byte
Inkey(SBUF0);
}

if(TI) {
TI=0;
if(fifo0[0][x]) {
SBUF0=(fifo0[0][x]);
x++;
out0_busy=1;
}
else out0_busy=0; // no character to send
if(!fifo0[0][x]) { // end of string last character is being sent
if(out0_busy) { // last character is being sent
for(i=0;i<FIFO0SIZE-1;i++) { // rotate buffer
if(fifo0[i]) { // if = 1 = buffer not empty
fifo0[i]=fifo0[i+1];
x=0;
} // if fifo0 buffer not empty
else {
if(i<2) SBuff0_Full=0;
break; // end of buffer
}
}
}
}
}
}

Parents

0 Bob Dillon over 24 years ago in reply to Andrew Neil

I did look at the posting you refer to.
But it did not help.
This is a listing of the code. It looks like it should work.
What am I overlooking ?
I do not know what ?C?CLDOPTR does. I assume it extracts the byte at DPTR plus offset x and places the results in the A register.

This is the C51 source.

 451   2          if(fifo0[0][x]) {
 452   3          SBUF0=(fifo0[0][x]);

This is the ASM listing.

                                           ; SOURCE LINE # 451
0031 900000  R     MOV     DPTR,#fifo0
0034 E0            MOVX    A,@DPTR
0035 FB            MOV     R3,A
0036 A3            INC     DPTR
0037 E0            MOVX    A,@DPTR
0038 FA            MOV     R2,A
0039 A3            INC     DPTR
003A E0            MOVX    A,@DPTR
003B F9            MOV     R1,A
003C 850082  R     MOV     DPL,x
003F 758300        MOV     DPH,#00H
0042 120000  E     LCALL   ?C?CLDOPTR
0045 FF            MOV     R7,A
0046 6008          JZ      ?C0076
                                           ; SOURCE LINE # 452
0048 F599          MOV     SBUF0,A

Reply

0 Bob Dillon over 24 years ago in reply to Andrew Neil

 451   2          if(fifo0[0][x]) {
 452   3          SBUF0=(fifo0[0][x]);

This is the ASM listing.

                                           ; SOURCE LINE # 451
0031 900000  R     MOV     DPTR,#fifo0
0034 E0            MOVX    A,@DPTR
0035 FB            MOV     R3,A
0036 A3            INC     DPTR
0037 E0            MOVX    A,@DPTR
0038 FA            MOV     R2,A
0039 A3            INC     DPTR
003A E0            MOVX    A,@DPTR
003B F9            MOV     R1,A
003C 850082  R     MOV     DPL,x
003F 758300        MOV     DPH,#00H
0042 120000  E     LCALL   ?C?CLDOPTR
0045 FF            MOV     R7,A
0046 6008          JZ      ?C0076
                                           ; SOURCE LINE # 452
0048 F599          MOV     SBUF0,A

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