Copying Structs

Hi all,
I need some help about assigning two structures.

The simple Function

void CopyStruct(struct A *sSrc, struct A *sDst)
{ *sDst = *sSrc;
}

is translated to

; Variable 'sDst' assigned to Register 'R10/R11'
; Variable 'sSrc' assigned to Register 'R8/R9'
0010 F06A MOV R6,R10
0012 F048 MOV R4,R8
0014 F07B MOV R7,R11
0016 F059 MOV R5,R9
0018 E6F23600 MOV R2,#036H
001C DA000000 E CALLS SEG (?C_WCPYFF),?C_WCPYFF

How is the data copied? Where can I find the implementation of the library Function "C_WCPYFF"? (Keil C166 6.04a)

Thanks for your Help.

Regards,
Marcus