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_RBYTE problem - reads double when data is >7Fh ?

Hello,

Below is a sample code for main.c, which writes 3 different SFR locations with various values.
What I noticed, and don't have explanation for, is that when the data is >7Fh, the _rbyte reads it as double, not char.

main.c

#include <REG51XC.H>

sfr SFR_REG1 = 0xF8;
sfr SFR_REG2 = 0xF9;
sfr SFR_REG3 = 0x91;

void main (void) {


    SFR_REG1 = 0x01;
    SFR_REG1 = 0x11;
    SFR_REG1 = 0x20;
    SFR_REG1 = 0x30;
    SFR_REG1 = 0x40;
    SFR_REG1 = 0x50;
    SFR_REG1 = 0x60;
    SFR_REG1 = 0x70;
    SFR_REG1 = 0x77;
    SFR_REG1 = 0x80;
    SFR_REG1 = 0x81;
    SFR_REG1 = 0xF1;
    SFR_REG1 = 0xFF;
    SFR_REG1 = 0x27;

    SFR_REG2 = 0x01;
    SFR_REG2 = 0x11;
    SFR_REG2 = 0x20;
    SFR_REG2 = 0x30;
    SFR_REG2 = 0x40;
    SFR_REG2 = 0x50;
    SFR_REG2 = 0x60;
    SFR_REG2 = 0x70;
    SFR_REG2 = 0x77;
    SFR_REG2 = 0x80;
    SFR_REG2 = 0x81;
    SFR_REG2 = 0xF1;
    SFR_REG2 = 0xFF;
    SFR_REG2 = 0x27;

    SFR_REG3 = 0x01;
    SFR_REG3 = 0x11;
    SFR_REG3 = 0x20;
    SFR_REG3 = 0x30;
    SFR_REG3 = 0x40;
    SFR_REG3 = 0x50;
    SFR_REG3 = 0x60;
    SFR_REG3 = 0x70;
    SFR_REG3 = 0x77;
    SFR_REG3 = 0x80;
    SFR_REG3 = 0x81;
    SFR_REG3 = 0xF1;
    SFR_REG3 = 0xFF;
    SFR_REG3 = 0x27;

    while (1) {
    }
}

functions.ini

signal void rbyte_test1 (void) {
  char mydata;

  while (1) {
    wwatch(D:0xF8);
    mydata = _RBYTE(D:0xF8);
    printf("0xF8 Read : %x\n",mydata);
  }
}

signal void rbyte_test2 (void) {
  char mydata;

  while (1) {
    wwatch(D:0xF9);
    mydata = _RBYTE(D:0xF9);
    printf("0xF9 Read : %x\n",mydata);
  }
}

signal void rbyte_test3 (void) {
  char mydata;

  while (1) {
    wwatch(D:0x91);
    mydata = _RBYTE(D:0x91);
    printf("0x91 Read : %x\n",mydata);
  }
}

rbyte_test1();
rbyte_test2();
rbyte_test3();

Here is the output after executing the code :

0xF8 Read : 1
0xF8 Read : 11
0xF8 Read : 20
0xF8 Read : 30
0xF8 Read : 40
0xF8 Read : 50
0xF8 Read : 60
0xF8 Read : 70
0xF8 Read : 77
0xF8 Read : ffffff80
0xF8 Read : ffffff81
0xF8 Read : fffffff1
0xF8 Read : ffffffff
0xF8 Read : 27
0xF9 Read : 1
0xF9 Read : 11
0xF9 Read : 20
0xF9 Read : 30
0xF9 Read : 40
0xF9 Read : 50
0xF9 Read : 60
0xF9 Read : 70
0xF9 Read : 77
0xF9 Read : ffffff80
0xF9 Read : ffffff81
0xF9 Read : fffffff1
0xF9 Read : ffffffff
0xF9 Read : 27
0x91 Read : 1
0x91 Read : 11
0x91 Read : 20
0x91 Read : 30
0x91 Read : 40
0x91 Read : 50
0x91 Read : 60
0x91 Read : 70
0x91 Read : 77
0x91 Read : ffffff80
0x91 Read : ffffff81
0x91 Read : fffffff1
0x91 Read : ffffffff
0x91 Read : 27

Any suggestions ?

Thanks in advance.