Who modified my local variable?

[Laurent R]

Hi,
  I met a problem as show below:

void FunctionA(unsigned char *pLen)
{
    *pLen = 16;
    printf("T2 %d\r\n", *pLen);
    return;
}

void FunctionB(void)
{
    unsigned char ucLen = 0;
    printf("T1 %d\r\n", unLen);
    FunctionA(&ucLen);
    printf("T3 %d\r\n", unLen);
    return;
}

  It is a multi-process project. One of the process will call FunctionB, but 
the result is not 0->16->16. It is 0->16->0. There are several other 
processes running in the backgroud. But there is no pre-empt process related 
to this function, or re-entry call of this function. I don't know who modify 
my local variable?
  Who can help me to think out other reason to modify my local variable in 
this example?
Br/Laurent

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