Practical Reverse Engineering p. 78 #2

Question number 2 on page 78 of Practical Reverse Engineering is as follows:

Figure 2-9 shows a function that was found in the export table.

Here is the function's disassembly:

Figure 2-9. Practical Reverse Engineering. © 2014 by Bruce Dang

 We can immediately tell the ARM processor should be in Thumb state. This function checks if the struct passed is NULL. If it is not, then one of the members is checked to see if the byte equals 0.

BOOL check_struct_char(struct *r0)
{
    /* CBZ R0, loc_C672 */
    if (r0 != NULL)
    {    
        /* LDRB.W R0, [R0,#0x63] */
        /* SUBS R0, #0 */
        if (r0->Unknown0x63 == 0)
            return FALSE; 
    }  

    return TRUE;           /* MOVS R0, #1 */
}

And here is a definition of the passed struct:

struct r0
{
    BYTE Unknown0x0[0x63];  /* 0x0 */
    CHAR Unknown0x63;       /* 0x63 */
}