Practical Reverse Engineering p. 79 #3

Question number 3 on page 79 of Practical Reverse Engineering is as follows:

Here is a simple function:

01: mystery3
02: 83 68 LDR R3, [R0,#8]
03: 0B 60 STR R3, [R1]
04: C3 68 LDR R3, [R0,#0xC]
05: 00 20 MOVS R0, #0
06: 4B 60 STR R3, [R1,#4]
07: 70 47 BX LR
08: ; End of function mystery3

The ARM processor is in Thumb state. This function just copies some values from the first struct to the second struct. It always returns 0.

int copy_struct_values(struct *r0, struct *r1)
{
    /* LDR R3, [R0,#8] */
    /* STR R3, [R1] */
    r1->Unknown0x0 = r0->Unknown0x8;                

    /* LDR R3, [R0,#0xC] */   
    /* STR R3, [R1,#4] */
    r1->Unknown0x4 = r0->Unknown0xc;

    return 0;   /* MOVS R0, #0 */
}

Here are the struct definitions:

struct r0
{
    BYTE Unknown0x0[0x8];   /* 0x0 */
    DWORD Unknown0x8;       /* 0x8 */
    DWORD Unknown0xc;       /* 0xc */
}

struct r1
{
    DWORD Unknown0x0;   /* 0x0 */
    DWORD Unknown0x4;   /* 0x4 */
}