implicit declaration of function 'epcs_read_buffer' warning

hi,
i study an458 for boot loader.
i build advanced_boot_copier, but not working.

waring is implicit declaration of function 'epcs_read_buffer'

code is

epcs_read_buffr(epcs_controller_base, epcs_contoller_register_offset, (int)src, (alu_u8*)dest, (int)num);

that is right? or worng?

plz, help me.